Monthly Archives: September 2014

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!