Monthly Archives: August 2014

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.




Lessons learned…

I’m 44 years old this year, you would reckon I’d learn. But as they say on all those dodgy Ebay listings; “My loss is your gain” – yeah right mate! Hopefully someone will get something from this though, as we get older we get complacent and we shouldn’t. Usually we don’t bend, bounce and stretch like we used to and when we do real damage, you don’t heal like you used to, and it seems like we are never the same years after recovery. We also have responsibilities like people who rely on us to be bread-winner and other social moulding!  Anyway…on with the lesson…

It has been a while since I had been on an outing on the AG, I had a few new bits on my test mule and I was interested to get a ride in to see how it changed the bikes feel, if any. It has been a cold winter in country Victoria this year, some would say unseasonally cold but they would be young folk and those with short memories; these are the winters we used to have when I was growing up on the farm in the eighties. Puddle freezing winters! Fourteen years of warmer winters and low rainfall can make people forget, but I digress.

A bit of fine weather enticed me to load up my trusty Falcon ute and do a trip out to the family farm. There I unloaded and my brother and I decided to go for a bit of a squirt around the farm. Usually I use the farm as a base to unload and hit the back roads as the recreational registration allows me. So it was a bit of a warm-up around the farm before I hit the back roads to do some exploring and AG-testing. Didn’t get to that second bit though…

Problems can arise when the risk factor goes up. Of course I had a helmet, goggles, jacket and gloves on but didn’t bother with boots or any leg protection – I was just blasting around a paddock after all. I could argue that this thinking was sound until I decided to have a ride around some dam banks. This changes things completely. The risk goes up and the probability of things going pear shaped go up with it.

The banks were steep and covered with high weeds where in places you didn’t know what was under them and you couldn’t judge the terrain. But I went barrelling on in, confident I could handle a few mounds of dirt. I got to the top of a bank and the bottom of the AG hung up and I lost traction so I thought I would roll it back a bit so I could get a run up to get over the peak of the bank. Before I could even mutter the magic “F” word (Forheavensake!), I was watching myself in slow motion falling over and down the bank on my right side, with the AG following me down!

My right elbow hit first and there was an almighty snap. Ok…my first broken bone! Then the AG came down on top of me and my right foot told me in no-uncertain terms to get this 100+ kg blue, steel pig off it now. After all the sound and motion stopped, I decided to do an audit (as you do when your an engineer 🙂 ), I twisted the right forearm and awaited a new dimension in pain to come from at least one shattered bone. You could imagine my relief when no pain came but I noticed an old, dry branch smashed to bits under my arm! The snap didn’t belong to me!

I now turned my attention to my foot which was still stuck under the right side engine case. The bike was laying down on me past the horizontal and had me pined under it via the said foot. Help was needed to extract myself and this came in form of a brother (also AG200 mounted) who couldn’t stop laughing! We managed to free myself from the situation and it was great to see that I had broken the fall of the bike and it had escaped any damage whatsoever!

AgfootI have had some monumental get-offs in my riding career. Hitting trees, end of main straight high-sides, low sides, but I have never done myself much damage. A bit of bruising here and some leather burn there. I guess I have been lucky. Once again I escaped with a pretty ugly looking foot, bruised elbow and a trip to the chiropractor to give my neck a tweak, oh and those unmistakable facial expressions and body language that health professionals can display to make you feel like a moron without saying a word!

Getting older makes you wonder if it was luck. If I was lucky I wouldn’t of crashed! Sometimes you have to make your own luck, or at least give it a bit of a hand. I could of avoided the damage of this accident if I had followed one simple rule – avoid any technical obstacle with the gear I had on…not perfect but the chances of me having this accident would of reduced to nearly zero if I had stayed away from the dam banks.

And it then makes me wonder about the AG200. If I was on my TTR250, I probably would not of had this accident and even if I did I probably would of had on my full suit of riding gear. I guess it comes back to staying within the AGs capability parameters. I shouldn’t of been on that bike in that location. I ride the AG to get me to places out of the way, economically, quietly and reliably. Doing this stuff on the AG is not dangerous, but it can increase the odds of something going wrong.

So to end the sermon, ride within you and your bikes means. Wear your riding gear. Most importantly in my opinion, use your brain. If you’re by yourself and/or a long way from home, think about your surroundings; do you need to go this fast? Do you need to be on this wet road? Do need to pull this mono? Do you need to do this power slide? Pick your time and place to have fun, and when it comes to the AG, ask yourself if you need any fun! Or is the destination the goal?