Category Archives: Service tips

Carb servicing part 4 – reassembly

The end game is here. Reassembly. One step closer to a smooooooth running bike! Its going to be a big post though so let’s not muck about…

Throttle shaft sealLets start with the throttle shaft (assuming you removed it). Throttle shaft+springTake a look at the photos and hopefully you can see which side the shaft slides into. From this side, install the rubber seal. Spread a small amount of grease on both ends of the shaft where it rotates in the carb body. Slide the throttle return spring along the shaft and set it up as shown at right. Now slide the spring and shaft into the carb body and make sure the spring legs Install shaftline up as shown by the arrows at left.

We can now insert the rubber seal on the opposite side, the plastic washer seal+washer+Eclipand follow it up by installing the E clip. Be careful the clip doesn’t grow a mind of it’s own and send you on an adventure to the darkest and hardest to reach parts of your workshop floor!

Eclip capCheck the operation of the throttle shaft and make sure its smooth and returns effectively. If all is well then install the E clip cover and tap it on lightly with a soft faced blunt instrument. We can turn our attention to the other side of the throttle shaft again Idle adj screwand install the Idle control screw and spring. Make sure you adjust the screw right through so it deflects the throttle shaft a significant amount. This will aid you with installing the butterfly as we shall see next.

align butterflyWe now need to do a bit of juggling because we have to rotate the throttle shaft to maximum open position while we slide the butterfly into the slot in the throttle shaft. Not as easy as it sounds but a bit of persistence will win the day! A set of soft jaws in a vice to (gently) hold the carb body might be a help here. It will free up a hand to help keep the throttle shaft in the wide open position. Have a look at my photos so you have the butterfly the right way round on your first try to slot it in – note the “120” indentation.

A little tip that may make the butterfly easier to manoeuvre, ispolished butterfly to clean it with some Brasso or other polish. The smooth surface wont hang up in the slot as much and I found it can help things out, and it looks purdy!

Once you have the butterfly in roughly the right location, slowly release the shaft and try and get the whole show located properly. Resist the temptation to get rough here because the butterfly is a fairly soft material and you don’t want to damage the edges or warp it. Take your time and use a pick or scriber to gently persuade the screw holes to line up.

butterfly with screwsThis is why I suggested to wind the idle screw in. It will help to stop the butterfly jamming in the home position and be a bit easier on everything. When the holes in the butterfly line up with the holes in the throttle shaft, gently insert the butterfly screws into the assembly. Don’t do them up too tight and don’t use thread locker, they are tight enough in my experience.

Now that everything is in place and tightened up, rotate the throttle shaft and make sure it opens and returns smoothly. The last thing to do here is get some strong light and make sure there is no brass swarf as a result of sliding the butterfly through the throttle shaft slot. Inspect both sides of the butterfly.

screw & partsTime to move onto the pilot adjust screw, check the parts at left – theassembled screw and its O-ring, spring, washer and another O-ring for the shaft of the screw needle. The easiest way to assemble this into the carb without potentially losing bits and/or not having the washer and O-ring seat properly, is to point the needle upwards and assemble the bits down over it in order. First the spring, washer and O-ring.

installedThe O-ring should hold everything on the needle shaft but why risk it? Grab your carb, turn it upside down and lower it down onto the the adjusting screw and its assembly of parts – easy! Screw the adjuster gently all the way down into it’s hole until it bottoms out, then screw it out two turns – the factory spec. You will find somewhere between two to two and a half turns will be optimal when the bike is running again.

EmulsionNext to go in is the emulsion tube. You have inspected the top, inner holeemulsion inserted of the tube right? And the needle? Good, now have a look at the other end that has the thread cut into the inner part of the tube, see the slot on the outside of the tube? This section has to interface with a brass post pressed into the main jet tube of the carb body. Slide the emulsion tube in through the top of the carb and wiggle it home as shown at right.

main jet+washerWe can now insert the “active” components into the float chamber. Startpilot jet with the main jet and its’ washer. Remember you are working with soft and brittle materials here, not too tight. Install the pilot jet next followed by the fuel/float valve. If the O-ring is OK I like to put a bit of rubber grease on it to help it to not bind when you insert it. I do this on most O-rings actually, it just seems to go back together nicely float valvewithout having to force the rubber.

Now the last few bits to finish off the float chamber. The fuel valve retaining bracket is next and then the plastic main jet shroud. I forgot to showmisc installed the pilot jet plug in this snap (at right) but its there in the final pic after I installed the float assembly.

Slide the float valve needle onto the float tang and manoeuvre it all down into the chamber and focus on the needle going into the valve. Line the float pivot hinge up with the holes in the float posts and slide the pivot pin through both items. I use a pair of adjustable-jaw float installplumbers pliers to gently press the pin into the interference fit of the posts of the carb body. That’s most of the float area done, we just need to put all donethe bowl on and screw it down. Note that the picture at right showing the assembled float chamber has the pilot jet plug installed as mentioned above.

Now I’m going to have a bit of a break from assembly talk for a moment so I can explain a huge hole in my tutorial. You may of picked it up – what about parts replacement? I have mentioned replacement of the emulsion tube and needle if they are worn but what about all the other parts of the carburettor? Surely some other bits here are consumer items? Yes, yes there are. Mostly the rubber parts – O-rings etc..

I have left consumable replacements out of this blog for the moment because it is a whole new discussion. If your carb is in reasonable condition then you can re-use most of the rubber components. If your AG200 has been sitting for a long time and/or it’s an older model, then there is a better than average chance that all the rubber components (maybe with the exception to the float needle valve) in your carb are shot.

So what can you do if you have dodgy rubber bits? Wait for my next blog! I am researching stuff at the moment and will have options to discuss but if you’re in a hurry then I’m afraid its off to your local Yamaha dealer to get pillaged!

Float bowlBack to the carb…time to screw on the floatbowl screws bowl. Nothing hard about that except you can use the old gasket if its still in good shape and take note that one screw has a loop for the float chamber vent hose. Have a look at some of the proceeding pics and you will see at what corner this loop is attached to. You can see two bits sitting in the middle of the gasket at left, disregard the pilot jet plug (you should of already installed it!) but you better put the float bowl drain screw in!

pilot air jet2That’s the bottom of the carb done, spin it over and now we turn our attention to the top part where the slide and diaphragm go in. Before we can install the slide assembly we need to screw in the pilot air jet as shown at left. Now we can assemble the slide. Something else I probably should of mentioned earlier in my “carb cleaning” series of blogs is that I don’t clean the slide or diaphragm. Well I don’t clean it in respect to chucking it in an ultrasonic bath or drown it in carby cleaner! I find that the diaphragm is a pretty delicate thing so I just clean it and the slide down with a rag and maybe blow a bit of air down the slide to clean up the area where the needle goes.

slide needle bitsThe needle assembly needs to be needle assembledassembled before it can go back in the slide. Check it out at right, the plastic washer with the alignment pin goes UNDER the E clip (with the pin facing down or facing the tapered end of the needle) and is slid on from the tapered end of the needle. The other plastic washer fits on the the top of the needle on the other side of the E clip. The spring then fits over the washer. Using your third hand ( 🙂 ), insert this assembly down into the slide.

needle alignmentThis little pic from the manual probably in slidebest shows how the needle assembly has to align into the slide. Once you get all the bits together into the slide, gently spin the needle until you feel the pin and hole align and the needle will drop a few more millimetres into the slide. Now you can carefully drop the needle retainer plate down into the slide and insert the two Philips screws to hold it in.

slide installedNow we can slip the slide assembly into spring+cap installthe carb body taking note of the alignment notch for the outer rubber ring of the diaphragm. Install the slide spring into the slide and install the diaphragm cap taking note that the spring stays even and the indent in the cap faces the airbox side of the carb. Do up the four screws in the cap and you’re all done.

throttle cable bracketThe lucky last bit to install will be the throttle cable bracket. It’s a pain to do all the other jobs to the carb with this thing on so I leave it ’till last. It can be a pain to get back in because you have to turn the throttle shaft a bit to allow the bracket access to its’ lower locating pin, but it will fall into line eventually and you can then screw it into place.

Move the slide gently up in the carb with carb done!your fingers and it should smoothly return when you release it. Don’t forget to back off the idle adjust screw as well. Apart from that you are ready to go! You could hook up the fuel to it to make sure the needle valve is working OK. You could also check the float level as described in the manual. Apart from those options, install the fuel line, overflow and vent hoses and you can get it back into the bike and see how she goes.

What an epic post! Now taking donations! It feels good to get it all down though and hopefully it will help owners with probably the most common reason for AG200 stoppages. I know I may of left some people hanging a bit with the parts replacement bit to come, but I think that once I have it down people wont care about the order of things that much. And by the way…once this has all been done, don’t be tight and neglect to install a good filter! It defeats the purpose of all this hard work.




Carb servicing part 3 – cleaning

Now we get to the boring bit – cleaning! But in respect to a carburettor, it’s the most important part because if you rush it and cut corners you will be pulling the carb out of the bike again – I guarantee it! The hardest parts to clean in a carb are usually the ones that block and cause trouble in the first place. Take your time and get everything as clean as you can and you will have success. Let’s get into it…

OK…what will we need in the way of tools and consumables? I have already covered the screwdrivers required and what to watch for in relation to them.  You will need a can or two of carby cleaner, compressed air, a small brass brush, cotton buds, rags (preferably clean and white so you can see what comes off on them), your workplace needs access to strong light so you can see through the holes in the metering jets to make sure they are clean.

protectionAs for safety – I have already mentioned gloves, some eye protection is essential because you will be dealing with high pressure air and cleaners. I prefer the full face shields because I am ugly enough thank you very much and I don’t want to be made more so by high-velocity bike bits! Think about ventilation and air circulation as well – too much carb cleaner vapours are not good for health.

What about an ultrasonic cleaner? Do you really need one? If you go and spend some bucks on a cleaner don’t think it’s going to do all the hard work for you. Cheap ones will do a reasonable job but only expensive, dedicated high power units will get them close to spotless. The cheaper ones like the one I use will get stuff reasonably clean but can’t go the extra mile with hard to move deposits. Do you really need one? No, not if you are doing just one carb. Just get yourself a couple of cans of carby cleaner and don’t be scared to use it.

Even if you do have a ultrasonic cleaner, if your AG is fumy and the carb was sucking a lot of oil vapour via the crankcase breather, a cheap ultrasonic cleaner may not get the job done. A solvent like carby cleaner will be needed to clean the baked oil residue out of the venturi of the carb. This is a good “tell” on the condition of your bikes engine; black oil residue in the main air-flow passage? You are probably going to have to do some engine work soon. But let’s get the carb sorted first.

carb bodyI separate the components into two groups; the main body parts, and the small, functional parts. I can place the carb body, float bowl, throttle shaft, cable bracket and other larger parts into the bath of my cleaner. You may have a different size and have to spread your cleaning out differently. I pour hot water into the in the bathbath and add a small amount of dishwashing liquid and set my heat on max (70C in my case) and run the ultrasonics for an hour. Sometimes I have to give it another thirty minutes or so but an hour usually gives me pretty good results.

small bitsThe brass brush will come in handy here. Use it to break up any caked on crud on the outside of the carb body. Pull the parts out of the cleaner one by one every 10 minutes or so and give them a bit of a brush if stuff is hanging on. Don’t try and jam the brush down the venturi if there is baked on oil, let the carb cleaner do that job later.

When the parts are done, you need to get them dry. If you live in Australia or another country with an excess of sunshine, get them into the sun and let them cook! after washIt won’t take long for the Aluminium and Brass components to heat up to the point where water won’t hang around them. If there is no sun to use, get them in front of a heater to dry off. Temperature and time is what you need to get them moisture free. Of course you can use compressed air to blow all the water out, which I do but I also like to heat it up as well. If you’re happy with just the air then happy days.

Choke & pilot adjNow that everything is relatively clean and dry, it’s time to get serious with the carby cleaner. Let’s start with the carb body. You have your gloves and eye protection on right? Give the carb a good blast with the cleaner and try and let the cleaner sit on the aluminium without evaporating. Lower temperatures will help here so try and do it out of daylight. Choke & pilot passLetting the cleaner soak into any deposits will help you a lot. If there is significant oil deposits in the venturi, use a rag covered finger soaked in cleaner to give the area a good scrub. Some choke pickupcotton buds soaked in cleaner may help in harder to get areas. Blast the whole thing with compressed air paying particular attention to the small passages leading to the pilot jet/bypass and choke plunger. Rinse and repeat!

In this photo at left you will see a view of the bottom of the carb looking into the upper float chamber – see the arrow at the bottom pointing into a large hole? That’s the float chamber vent. In some bizarre law of physics that follow the same laws as coat-hanger reproduction and socks always being odd, grass seeds accumulate in this part of the AG200 carb. Don’t ask me how they get there but they do!

Now onto the smaller components. With or without an ultrasonic cleaner, you now need to focus on the brass jets. They are the heart of the fuel metering function of the carby so they have to be spotless for it to function correctly. Clean all the brass jets until no more crud comes off them onto your clean rags. Soak them like I recommended for the body above.

Needle&emultion2Take a close look at your emulsion tube and look for the sixteen small holes (1) in the body of it and make sure they are all clean. Use the four holes on one side to line up with the four on the opposite side – light needs to shine through all eight. Have a real good look at the top of the tube (2) where the needle goes in and if you see any wear or elongation of the brass, replace the emulsion tube and needle as a set. Have a good look at the needle’s taper particularly at the upper end (3) and again, if wear is present replace the set as stated.

I probably should of left this to the next part of “inspection and assembly”, but like the rubber diaphragm mentioned in my last post, if you don’t want to pay the money for parts then this is the time you stop working on your carb and start looking for another one to clean up. The bike will run like a dog with these parts worn, and no amount of carb tinkering will get it to run right until you replace them.

needle valve+filterThe fuel needle valve is next…was it leaking fuel before you valve cleanstripped the carb? If it was, don’t chuck it out just yet. The rubber on the tip of the needle is very robust and I would suspect the valve body myself. This is a problem area on the AG200 because there is a filter gauze on top of the valve that you would of seen when you pulled it out of the main body. Without a proper fuel filter, anything that gets past the tank filter will accumulate here and can make a bit of a mess. Gently pry the filter off the top of the valve and soak the whole thing in cleaner or put it back in valve clean2the ultrasonic bath if real bad. Remove the O-ring if it hasn’t already disintegrated. I have found that sticking a cotton bud soaked in carb cleaner and rotate it in the needle side of the valve will nearly always get it working again. Physical wear is not really an issue with these valves because it’s rubber Vs brass, and the rubber is pretty tough. Corrosion is nearly always the culprit and once hit with some chemicals they nearly always work well again.

Soak the pilot, pilot air, and main jets in cleaner and blow them out. Make sure you can see through their metering holes and that there are no obstructions. misc partsDon’t go sticking things in the jet’s metering holes if they are blocked, be patient and soak them in cleaner and use compressed air – it will shift the deposits eventually. Don’t forget other brass bits like the throttle butterfly, choke plunger, pilot air screw adjuster and get them as clean as your persistence and patience will allow!

Carb bitsFor all the other parts, I suggest a brush over with the brass brush to clean them up. Bits like screws and their threads clean up well with a bit of a brush up. Try and keep carby cleaner off rubber parts like O-rings and the slide diaphragm. They don’t like it but it evaporates pretty fast so don’t get too concerned. Most of the small O-rings like on the choke plunger bolt, needle valve and on the pilot air screw adjuster will probably be stuffed, but I will discuss all this in part 3.

For now we are pretty much done with the clean. I didn’t get too detailed – it’s all common sense really. Just get things as clean as you can and blow it all out and you will be done. Next we will cover re-assembly and what to look out for and some other tips.



Saftey gear – protect your skin with gloves

Maybe I should of made this post before we started work on the AG200 carb. Or maybe it should of been added right at the start of this site – blog number 1! Why? Because I think it’s important, and yes you have seen pictures of me doing work in bare hands but trust me…I pay for it later on.

The founder of the Jesuits had a saying; “Give me the child for the first seven years, and I will give you the man.”  There’s so many things I hate about this saying on so many levels! But the thing I can take from it without frothing at the mouth is that the things learned while you are young can become second nature and easy when you’re an adult.

Take workshop safety. Farms are renowned for not being safe places, and I grew up on one with little care for safety, in regards to long or short term health. When you don’t have a role model or someone to learn the basics from, you get into bad habits that could stay with you for the rest of your life, which may be a short one if you don’t quickly learn!

glovesMy professional career was a different story. From my mid teens to early twenties I was schooled in the field of electronics where a careless action could mean death, pain, or if you’re lucky, an extended period of time cleaning up and repairing what you fried! I learned from good teachers in a formal, structured environment where attention to detail was expected. This attitude extended out into the workforce where the engineering mentors I had were up with the latest trends not only in our field, but also in safety and the changing legislation that effected the workplace.

When you work in this environment for twenty years and then go back to doing some of the things you were doing when you were a kid, you realise how bad it was and some of the bullets you dodged! The dangers of raw fuel, solvents, old oils, coolants and other chemicals you were exposed to because no one told you otherwise. Not to mention the protective equipment that most take for granted like ear and eye protection.

Most people get ear and eye protection – its a no-brainer. A lot of people don’t get skin protection though. If you watch Youtube videos the Americans get it. Even the roughest mechanics over there wear rubber gloves when dealing with engines. We haven’t really caught on in Australia yet. But I am here to tell you that you should use them if you are working on engines. It is especially relevant when working on bikes that have been sitting around for a while because once you get old stale fuel on your skin, the smell with be with you for days. Not to mention the long term health effect of getting this stuff on the skin either.

You don’t have to wear them all the time like working on wheels or chassis stuff (mechanics gloves are better here) but if you are doing anything with fuel, coolant, carby/brake cleaner and oil, you really should keep this stuff off your skin. I know, my pictures on this site don’t exactly show me with them on all the time – I’m still working on not being a slacker and feel I am slowly winning the war on bad habits learned in my youth…it takes time.

Have a look on Ebay for nitrile gloves. You can get a box of 100 for less than $15 and they last for ages. There really is no excuse for using this safety item every time you hit the tools out in the shed. Skin does an amazing job of protecting us, show it some respect. Do it a favour and you won’t stink of stale fuel for a week after touching it. Something that partners and pets really appreciate I have found!



Carb servicing part 2 – disassembly

Now we have the carburettor out of the bike we need a nice clean work area. Some nice clean rags and a work space where small bits can’t get lost or roll off the bench. We also come to a dilemma in my normal, cheap-as-chips servicing guides – I use an ultrasonic cleaner to clean my carbs. Not that ultrasonic cleaners are that expensive these days, but I can understand if someone didn’t want to spring for one just to do a single AG200 carby.

After years of doing it with the basics, like carby cleaner and compressed air, I found that with AG bikes, the neglect has usually been severe. The built up crud from around twenty thousand ag-kilometers (equivalent to one hundred thousand normal Kms 🙂 ), and then getting chucked in the shed for 10+ years to let corrosion and old fuel do their work…well, sometimes carby cleaner isn’t enough.

It all depends on the condition of the carb. If the bike is running and is not too old then a bit of compressed air and carb cleaner may do the trick, but so many times I’ve had to remove the carb multiple times to get it right. I will admit though that was always with bikes that were really bad. What I like with ultrasonics is that you get it right every time. Its very effective when the carby is fully disassembled.

So all I can do is roll on here and show you how I do it and I suggest you get yourself a can of carby cleaner and access to compressed air if you want to do it without ultrasonics. Carby cleaner will still work well if you disassemble the carb like I do here and clean it all out and make sure any varnish, dirt and corrosion is removed. It may take a bit longer and you might have to be a bit more observant on your results but in the end you will get the same thing – a nice clean carb that works the way it was supposed to when it left Yamaha.

Throttle slide cover
Top cover

I will make a quick mention about tools; I have already done a post on JIS screwdrivers, you can get by without them and good quality screwdrivers (especially European ones) seem to fit reasonably well – just be careful and observant. If the driver doesn’t fit nice then try another. Screwdrivers for the slotted heads on the jets are a different story. Don’t tolerate a poor fit here; they are made of brass and there is a good chance they are effected by corrosion, varnish and/or caked on sediment. You will only get one chance with these jets. If you hack the slot on them you will be in a whole world of pain trying to get them out.


OK, the first thing to do is remove the top throttle slide/diaphragm cover. It pays to check this first because if the rubber diaphragm is split or torn then you need a new one and if you don’t want to pay for the Yamaha part then there is no point going on with the clean. So remove the four screws and remove the pressed steel diaphragm cap and slide spring. Slide the throttle slide and diaphragm assembly out and inspect the rubber closely. If it looks OK, store the assembly so it isn’t placing any weight on the diaphragm.

Needle bits
Needle bits

If all is good then you can proceed to disassemble the slide/needle assembly. Look down the top of the slide and you will see two Philips screws holding a metal plate. Have your wits about you when you remove the screws because there is a spring under it. Don’t get too stressed about how it all goes together because I will show all that in the re-assembly blog that’s to come, just make sure its all in bits so you can clean it up good. It also might be a good time to inspect the needle and take note of any wear because it will be helpful in diagnosing any running problems later on when its all back together. Cleaning will only do so much on the AG200, if the needle and emulsion tube are worn, the bike wont run well and you will have to replace them as a set. I will cover this after this series on carb cleaning.

Misc. bits
Misc. bits

Time to remove miscellaneous bits off the carb body now. Start with the three hoses if they are there – the fuel line, bowl drain and float chamber vent. Remove the idle control adjuster and spring and the throttle cable holder bracket.

Top jetsNow we turn our attention to the top of the carburettor. The picture to the left shows the pilot air jet (1) and the pilot  screw (2). If they look like they have corrosion issues (especially the jet) then a squirt of your fav. penetrate and a cup of coffee might be what you need! Otherwise just unscrew them and put them aside. Just be aware of the spring under the pilot screw when you remove it and down underneath that spring will be a steel washer and under that a tiny o’ring. These parts are tiny and like to flick away onto the floor or in other dark places never to be seen again so be on guard!

bowlNow we have a nice flat surface to stand the carb on the bench upside down so we can concentrate on the float and underside parts of the carby. Remove the float bowl drain screw first then the four Philips screws holding the bowl on. Remove the bowl and you should be greeted with something similar to as shown here on the right.

carb underside

A bit of a look in the bottom of the float bowl will tell you (if you don’t already know!) what sort of a battle you will be up against with the rest of the carb. Is there corrosion or just varnish or neither? While you are looking, remove the plastic shroud from around the main jet and the rubber plug from the pilot jet tube and the bowl gasket and put them aside.

Float removalGet yourself a fine pin punch and lightly tap out the float pivot Needle valveand remove the float and the needle from the needle valve assembly. I have read so many horror stories about Mikunis and their float pivot post breakages. I have never found one in an AG200 to be that tight that it causes issues, but be careful with it and if tight, relive pressure on the post by laying it on a solid surface. A single Philips screw fastens the bracket that holds the rest of the needle valve assembly into the body of the carb. Sometimes the needle valve needs a bit of persuasion to come out because of the rubbish that can accumulate on the filter on the other end of the valve, a bit of penetrant to soak down onto the o’ring can help things out here.

Remove emulsionTake a look down the pilot jet tube and see how bad it is down there. If there is a lot of crud, try to get as much of it out as you can before attempting to remove the pilot jet. Some carby cleaner and compressed air should do the job. When you have it as clean as you can, put a good fitting slotted screwdriver down there and undo the jet. Now do the same to the main jet using a larger slotted driver and also remove the brass washer under the jet. After you have done this I use something plastic like a cheap pen case to tap the emulsion tube out through the top of the carburettor.

Now we could end it here and say the disassembly is complete and cleaning can commence, but I will give the reader the option of removing the throttle butterfly and shaft assembly. I often wonder if Yamaha ever expect it to be removed with the pressed on cap over the end of the shaft, but if the job is to be done properly then it should be removed and cleaned up. Having said this, I have left in place to do cleans where the carb is in pretty good condition. There are no air or fuel passages involved with theses parts so If the bike doesn’t run correctly it will be related to another area of the carburettor. I will leave it up to the reader on what they want to do but I will document the procedure below.

Shaft capIf you look closely at the photo at left you will see where I have the screwdriver placed to lever off the shaft cover. There is a nib in the alloy casting of the carb that will allow you to use as aShaft E clip fulcrum of sorts to lever the cap off. under the cap is an E clip that can be removed along with a fibre or plastic washer. There are rubber seals at each end of the shaft that fit into the carb casting, keep an eye on them. If they don’t want to come out while the shaft is still in place then leave them until you slide it out.

ButterflyFor the shaft to slide out, we now need to remove the two Philips screws holding the butterfly to the shaft. The brass butterfly plate passes through a slot in the shaft and is a pretty tight fit soThrottle shaft be patient removing it so you don’t damage (especially the edges) it. Take note of its orientation to make it easier for you to re-assemble. Be careful the return spring doesn’t skewer you when you slide the shaft out and watch for the seal on the spring side of the shaft.

bitsThat’s it! Full disassembly is complete. We now have a heap of bits ready for the ultrasonic bath or the contents of a carby cleaner can! My next instalment will go through how to clean it all up.



JIS screwdrivers

When I was a kid on the farm growing up, spending most of my free time working on motorcycles, I used to curse the Japanese manufacturers for making their fasteners out of cheese. You only had to release some of their Philips head screws once to tear the centre out of them or to deform them enough to know that next time you release them you were going to have issues. It was quite a few years later that I was to discover my ignorance.

Vessel JIS driverJIS – Japanese Industrial Standard. Yet another example of humanity’s inability to work together! Yes the Japanese version of Philips is slightly different to everyone elses. I don’t blame them, they wanted a better standard so they enforced it via their products, but no one else took it on and everyone went to Torx, hex or Allen heads anyway. JIS is still out there though, even though most of the AG200 fasteners are hex there are still the odd Philips fasteners here and there. Like on the carburettor and this is why I bought this up between my carb servicing blogs.

JISSCREWSIf you do a lot of servicing and repair to Japanese bikes, especially older ones, then get yourself a set of these JIS drivers. JIS is denoted by a small dimple on the head as shown in the pic here. They really make a difference and you won’t chew out the small Philips screws like I always used to do in my youth. They can be hard to track down in Australia so I got my latest set from RJR Cool Tools in the US. They have a listing for a set of 3 Vessel drivers specifically for bike maintenance; #1, #2 and #3 – they’re the ones you want…good value in my opinion too because they are a very good quality, Japanese made, screwdriver.

So there you go, you now know that you need three different Philips head screw driver sets in your toolbox to tackle anything; JIS, Philips and Pozidrive. Don’t even get me started on Torx!



Carburettor servicing part 1 – removal

If you manage to find yourself an old AG200 that has been lying around in a shed for a year or two and you want to try and get it going, take my advice – don’t bother! Not until you have cleaned the carburettor out anyway. Unless the farmer who owned it was a maintenance ninja (um…yeah) and drained the fuel out before laying it up in the shed, then the carb will be a mess and even if you do manage fire it up, it will suck all sorts of rubbish into the engine. Read on AG200 ninjas…

Float bowl drain
Drain float bowl
Choke plunger
Remove choke

First thing to do obviously is to remove the carb from the bike. Lots of bits can be removed to help in this so start with the fuel tank and the seat. I also like to remove the exhaust system. You can do it with it in place but it’s a pain. Another thing that makes it way easier when its out of the way is the rear shock and spring assembly, but unless you are doing a full strip down then leave it in place.


Cable removal
Throttle cable
Front manifold
Front clamp

Before removing the carby, I like to release the drain screw on the bottom of the float bowl to remove the fuel (if any) that may be left in it. It will save you getting covered in fuel when you remove the carb from the bike and you can let it drain while you remove the other bits. Place something under the bike to catch the old fuel. Stale fuel stinks and the smell lingers and seriously does not agree with me.

Rear manifold
Rear clamp
remove carb

First thing to remove is the choke cable and plunger. A 14mm open end spanner will help you with this. Then remove the throttle cable using a 10mm spanner to loosen off the adjusters in the bracket assembly.

Loosen off the two clamps holding the rubber manifolds on at the front and rear of the carb. Pull the carb to the rear to release it, the rear rubber manifold is a lot more flexible than the front so you can mash it up a bit to help get the unit free and out of the bike.

On the bench

When removing the carb, take note of where the overflow hose is routed and its relationship with other wiring that lives near it, It may help you getting it back together neatly without kinking hoses and so forth. You might want to stuff a rag in the inlet manifold while doing this work too.

There we go, part one down and the carb is out and on the work bench. Keep an eye here to read about the meaty bit of stripping down the carb.




AG200 brake shoes

If you asked me if there was one (there are many!) good reason why to choose the later, electric start AG200s, then it would be because of the larger front wheel and brake. The advantages of the 21″ front wheel won’t be discussed here but the larger front brake and the brake shoe options will be the topic for this post.

Tell me a motorcycle that has a smaller front brake than the back? No idea? Well I can tell you one – the early, 6V, non-electric start AG200. What a gooba of an idea! The wheel and brakes were lifted directly off the AG100 two stroke which in itself was under braked! The shoes were a tiny 110.0 x 25.0mm. One word comes to mind; “inadequate”! It’s one of the few brakes I’ve used on a motorcycle were when you use them you want to put your feet down to give them a hand!

This poor excuse for a brake was used for over ten years by Yamaha on the AG200 until around 1997 when they decided to upgrade the front end with the larger wheel and brake. We now had a whopping 130.0 x 28.0mm brake, we finally caught up with the rear as it has the same dimensions!

So if the dimensions are the same you would think the shoes would be the same right? Well they aren’t, they couldn’t get this right either! But I will excuse Yamaha for this engineering oversight because the front wheel came later and they couldn’t foresee the issues that arouse. Even though the shoes have the same dimensions, the rear units have too much meat on the inside casting to clear the speedo drive housing on the front backing plate. So even though the shoes should fit, they don’t. Two separate part numbers.

AG200 brake shoesCheck out the photo; The front shoes are on the left, the front, pre-electric leg AG200 is in the middle and the rear is on the right. Notice the front has less material in the alloy casting to clear the speedo drive? And you can see that there is a significant upgrade from the old front brake to the new one.

But hang on…if the back don’t fit in the front, do the fronts fit in the back? Do we only need one set of shoes for the AG200? Yes we do. The brakes on the left hand side also fit in the back just fine so we only really need this set of shoes for either end of the bike.

Now that we know what fits we can order a set from our friendly Yamaha dealer right? No…no we can’t/shouldn’t! I won’t even bother listing the Yamaha part number because the last time I went to a dealer I got quoted $75 for a set. This really is crap! And the dealer may not be the one blamed here, he is just trying to make a living (I hope). This is what happens when an importer/national distributor gets greedy. Setting a price that the market will bare rather than what is fair and reasonable. But that’s another blog…

So by all means, give your local dealer a call. Just make sure you’re sitting down when he gives you a price! I feel that no more than $30 should pull it up and you can get them cheaper again if you are prepared to dig a bit deeper. If you want a name brand, after-market set of shoes like Ferodo (FSB733), EBC (506) or SBS (SBS2034) then around the $30 should be about right.

Searching for after-market stuff for the AG can be a minefield because most of the after-market stuff is manufactured for the high volume markets that just happened to not have the AG200 on their model books (like the US). What can also make it difficult is that some higher selling volume countries did get the AG200 but only for a year or two (like the UK). This means they may have a listing but it would only be for the earlier bike, with the smaller brakes discussed above.

Luckily, Yamaha were well known for sharing a lot of consumable parts between models. This helps us to find bits for the AG without getting hammered by Yamaha Australia , who think we are all morons and will just pay up. Come on guys…I can buy Chinese shoes in one-off purchases to suit the AG200, out of the USA for $13. The AG200 is a 30 year old design and this part number goes back even further. My guess is it cost Yamaha $5US to get these things made and they pass them on to us for $75…is that fair? Like I said…its another blog!

Anyway, I need to get off my soap-box and give you some useful information. Download the Ferodo PDF listing here and check out page 382. You are looking for part number FSB733. This will give you Yamaha equivalent numbers and other manufacturer cross reference. Page 154 will give you the fitments from other Yamaha models and even other manufacturers. This may help if you want to keep an eye out and gamble on buying some old genuine stock that might be going cheap on Ebay or some other location.

I’m getting hints that Ferodo’s part FSB947 is also a replacement for the AG. Page 486 of the catalogue if you want to check it out but I haven’t tried them yet so can’t guarantee their fitment. Will update here when I find out. What I do know is that the FSB733 does fit and I am using them in AG200s now.

Of course the other manufacturers list in this Ferodo catalogue have their listings and information too so there are other potential information sources as well but from the ones I have looked at so far, I have found the Ferodo one the most informative and helpful to date. I will keep up the hunt and if I find something more useful to the AG owner in the future I will make sure to post it up.

There is the other reason I have gone with Ferodo; I can get them, they are a reasonable price, I have used them and they work well. I will be keeping an eye out for any other option though and will update when I get more info.



Stand slop…

Ever wondered why so many AG200s have worn out stand pivots? You’ve seen it before – heaps of play between the stand and the frame bracket to the point where the stand can (in the up position) be pushed back and rub on the swing-arm! You might think that it’s just because farmers are always on and off the bike and it just wears out. But here’s the thing…it happens to both stands and most people only use the one on the left side. Curious?

I’ve owned lots of bikes over the years and worked on heaps of others but I have never seen another model that their stands and mounting pivots wear and deteriorate like the AG200s. Every axis of movement on these stands seem to display excessive wear while the springs fatigue and fail, and sometimes the spring lugs can drop off!

Stand springIf you go and cross reference the stand spring part number of 90506-26270, you will find a heap of Yamaha models that use the same spring. BW200, YZ80, TTR110, PW80, XS400 and a heap of other bikes of small capacity that I don’t think were released here in Australia. Most of them are small bikes and even the big ones are road bikes so they have short stands with a small foot. The AG200 stands are not too long (~270mm) but they have a broad, pressed steel foot that has a slight dish to it underneath.

Stand foot, undersideSo what happens? Well, we have a spring that is borderline from new in its task of holding the stand in the up position. The weight of the relatively large foot allows the stand to bounce up and down over rough ground, wearing out the pivot. The clincher to self destruction is when clay or other soil types fill up the dished section under the foot, adds weight to the end of the stand and multiplies the whole effect. So as time goes on the spring gets fatigued, weakens and makes it worse again. The poor thing hasn’t got a hope!

When the spring is new and there is no extra weight under the foot then it’s all good. But it doesn’t take much to start the vicious circle of destruction for both stands. The fix is to treat the stand spring as a consumable item. At the slightest sign of the stand bouncing around check under the foot. If there is no build up, replace the spring.

P1020561The whole issue would be solved if Yamaha added a decent spring in the first place – PeeWee 80 spring – Pft! So I am on the hunt for a decent spring, preferably from another Yamaha model, I will update this post when I find it. But for now keep your feet clean, the pivot well greased and keep an eye on those springs!



Fork servicing part 4, alternative parts & tools.

Oh no…not more fork stuff from this clown! Yes but there is nothing more about working on them. This is about the parts used in them and what we can use from other models and other manufacturers. I also have a few tips on tools…lets take a look…

First of all, here are some dimensions that might come in handy if you are researching fork info for this bike. The inner tube is 35mm in diameter, this is the inner measurement for the oil and dust seal. The outside diameter of the oil seal is 48mm. The dust seal has an outer diameter of 48.5mm I presume to help with the interference fit in the fork because of its smaller thickness compared to the oil seal.

Some of the other Yamaha models that use the same seal are; YZ100 ’80-’81, DT125 ’82-’83, IT125 ’81, XT125 ’82-’83, RT180 ’90-’93, XT200 ’83, RD250 ’78-’79, RD250 ’76-’79, TZ250 C-D-E, XT250 ’80-’83, RD400, XS400, SR500, XJ500, XS500, XV535 ’88-’92, TZ750 (!!!). Some alternate Yamaha part numbers for the oil seal are; 10V-23145-00, 38W-23145-00, 1UA-23145-00, 29L-23145-00. Don’t quote me on all this, it’s just what I have found while cross referencing stuff. There is no way I can confirm this 100% because I don’t own or have serviced all these bikes. What I do know is that the YZ100 does fit.

As for after-market suppliers, some don’t even have a listing for the AG200 but you can go on the dimensions – Fork oil seal 35x48x10.5mm (35x48x11mm is also fine) ARI has a listing as ARI.003T, Vesrah – AR-3506, Emgo 19-90134 and Allballs 35-1011. The dust seal is a bit more complex because some hang up over the fork tube so it’s hard to say what their correct height is. The factory dust seals measurements are 35×48.5x5mm. ARI do a listing of ARI.049 but I notice the thickness is larger (8mm) but this may be because the design is different like the Pyramid Parts seal that I have tried and discuss below. Allballs do a kit listed as AB55108. I have never ordered any of these parts or kits except for the genuine parts and Pyramid, so do some research of your own if you’re going to go your own way.

Fork seal kitI have checked a lot of the after-market companies and their listings and have found a supplier called Pyramid Parts that sell a kit that is quite good quality. Their product code is F&D 013 & 066. They don’t have any listings for an AG200 but, as stated above, I do know that the 1981 YZ100H has the same fork seal dimensions as the AG200. I have purchased a few of the dust/oil seal kits and they work well. In fact, I think they are better than the genuine items. I haven’t had them running for extended periods as yet but the oil seal has a tension spring on the upper and lower lips while the dust seal has multiple lips that should work much better than the original.

Dust seals compThe only hitch is that your fork boots may hang up on the top of the dust seal when you lower the boot down on it. I have installed two sets of these seals so far and this only happened on one installation and only on one leg. I still managed to get the boot down OK and fastened the lower section of the boot with a cable tie. I suspect it was just the boot in this situation (it was a bit wonky). You can see in the photo here that the after-market dust seal on the left sits up higher on top of the fork, while the original dust seal on the right sits down in the outer fork housing flush with the top.

The YZ100H were shipped from Yamaha with fork boots but maybe it was a different design to the AG with more room at the lower section of the boot? Or maybe its just a oddity of the the after market? It is a much better dust seal than the genuine AG item, to the point where you could run the forks without the boots if they are damaged. So this kit is good for a few reasons – if your boots are wrecked, leave them off and just use this superior dust seal. If your boots are OK then you have the protection of them AND a better dust seal – you cant loose.

Fork seal kit#2Pyramid Parts has a shop on ebay Australia that sells these seals at $25.00 for a kit. It’s cheap and even comes with a little tube of assembly lube which is cool. Just be aware though, his feedback is poor because he is sloooow! You will be waiting for two weeks to get anything out of him but that is my experience of anything out of New Zealand. You can’t rush these Kiwis! 🙂 He says it’s Australian stock but from the mirth of his feedback I find it might be stretching the truth a bit. But who cares? You want stuff cheaper then something usually gives, in this case it’s the delivery time. Maybe I should do a bulk purchase from the company via their website and sell them myself? let me know what you AG200 owners think about this and I may start my own AG-only parts thing up.

Fork circlipIf your forks are full of water, which is pretty common, then the oil seal retainer clip will be in pretty poor condition and I strongly recommend replacing it. Any old garden variety bearing shop should have, or can order in, some internal circlips to do the job. Just ask for 1.75mm thick by 52mm internal circlip. Make sure they are seated correctly in the groove and they will do the job fine. You can get stainless ones too ($$$) but if you maintain your forks you shouldn’t get moisture past the dust seal. You will need to update your tools, a proper set of circlip pliers will be needed of course.

What about fork oil? Fork oil is hideously expensive for what it is. I pay well over $20 for 500ml. It’s too much I reckon. I have read around the web that a lot of people use Auto Transmission Fluid. Never tried it myself but I can understand why people would. I will stick with the proper stuff with my bikes but I can’t see how ATF would hurt on our more lowly steeds. It is just hydraulic fluid after all. The AG needs 15wt oil and I’m not sure of the viscosity of ATF, some say between 7.5 to 10wt so you may find the forks a bit quicker on the rebound action but what the heck…my view is that use proper fork oil if you can but if its a 100km trip to get it and/or you have a heap of ATF hanging around your workshop then give it a go.

Alternate oil seal driver!While we are on to alternate parts, here’s an alternative oil seal driver! The cam-chain side camshaft bearing in the AG200 is an alloy bush which I chuck out in favour of a roller bearing. It fits very neatly on top of the oil seal and does a good job of getting the seal in even. I will document this mod in an up-coming post so you too can get your very own, genuine Yamaha fork seal driver!

In my fork repair posts I also noted that you need to weld a 19mm bolt into a socket, well Fork damper holderthere is a cheaper way of getting that tool into your AG200 toolkit; just weld a 19mm bolt into a piece of pipe or on the end of piece of steel bar – what ever you have lying around really. Weld another piece of pipe or bar at 90° on the other end to make a big long T-bar tool (check out the “damper rod T-Bar tool” in the Yamaha service manual). Many moons ago I did this to get the forks apart on a road bike and it worked a treat so it will do the job for the AG. The bolt into the socket tool mod isn’t that expensive, but acquiring the 1/2″ extension and T-handle can add up. Just make sure the length from the bolt end to T-handle is around 55cm or longer to reach into the fork properly.

So there you have it…I don’t think there needs to be any more info on AG200 fork maintenance. We are done.



Flywheel viewing hole covers – a bit of bling!

Now I’m not one for gratuitous bling on my machines, particularly when they are humble machines! Machines where bling has no place! Billet and anodised  parts are lovely on a tricked up WR450, but an AG200?

You have already seen my gear lever replacement and you may of thought it was a bit over the top but due to the manufacturing wonders of China, we can all now enjoy a bit of flashiness here and there. But flashiness is not why I replaced the components you see here. The reason I replaced them is because the ones supplied by Yamaha are utter rubbish.

Old covers

Check out the photo of the original covers at left. You will see the two Flywheel/Magneto covers on the engine side case. They have a slotted tool interface. Who the hell still uses slotted fasteners? I despise them. Every chance I get I will chuck them out and replace them with something decent. I don’t care how “authentic” they make the machine look!

I check my valve clearances quite often. About every second extended ride actually. Why so often? Ever owned a five valve, multi-cylinder motorcycle? When something is so simple to check the valve clearances, you tend to keep an eye on it! So anyway, when you are removing the magneto covers to gain access to timing marks and the magneto nut so you can rotate the crank, you chew them out in no time.

You can see in the above photo that they were starting to get messed up. They are made out of cheap plastic (The earlier AGs were actually aluminium). Remove them and put them on your bench and firmly hit them with your biggest hammer, just to make sure they are never put into service again!

Timing cover

You can buy the GYTR units (for the TTR230?) but they are ridiculously priced so I went with some units from Zeta Performance Products, part# ZE89-1412. They wont add any performance to the AG200, but they will perform (last) much longer than the originals with their Allen/hex interface. And yes, they are from a YZ/WR 250F and they screw right in. I should of just bought a WR 250F and fitted racks to the thing!

All you need to do is swap the old o’rings off the old covers onto your new ones and screw them in. Don’t do them up too tight and maybe a little bit of grease on the threads will make them nicer to fit. You will now be ready to go and checking the valve clearances will be much nicer to perform.