'01 426 Advice?


I have recently made a deposit on the first '01 426 to hit the shelves in Southern WV. This is my first new purchase since a '96 KX500 and first thumper since a '79 TT500. Cant'wait. I would appreciate any advice on the purchase, early maintenance, setup, etc. Thanks. timdawg.

Welcome to the wonderful world of 426....

The first thing to do is grease all Your bearings, swingarm, suspention linkage and steering stem.

Then chainge oil and filter after run-in.

Check the rear sprocket bolts often.

Read all You can find in this forum, it has helped me a lot.

Just hang on and enjoy the ride.......


Yo timdawg and welcome. You can look way back in the older posts and find lots of info on these bikes. I posted one on my early maintenance experiences and got lots of good responses. Good luck with your new bike and have fun!



You might consider installing a good quality in-line fuel filter and plan on cleaning the carb internals soon after you have a little time on the bike. I have been trying to rid a severe popping from the exhaust when the throttle is chopped and couldn't eliminate it via adjusting the fuel screw. I found the pilot jet partially clogged with trash and the bottom of the float bowl contaminated with rather large particles of foreign matter. I carefully cleaned all jets and circuits with carb cleaner and also made sure the accelerator pump circuit was clean. When removing the crab, I discovered a small air leak at the intake manifold plastic boot. The bushing that the allen head mounting bolt passes through had slid out and was allowing a small gap between the boot and cylinder head. This could have been disasterous since raw dirty air was being sucked into the combustion chamber. Obviously, this was allowing a lean mixture and could be causing the popping. Hopefully, I have corrected this problem but won't know until I have everything reassembled and tested.

Are you folks using any special type of carb cleaner or can I use automotive? Also, how and where do you spray the cleaner? All over? Never cleaned my carb before, but I think it's time...



99WR,WR timing,throttle stop removed,Uni filter,E-Series pipe,carbon air box,Pro Tapers,lights removed,YZ tank,13 tooth sprocket

Scott, I used regular automotive carb cleaner to clean the jets and circuits. It's handy to install the little straw on the can and shoot the cleaner thru the circuits and verify that it's clean and operating properly. However, the cleaner creates havoc on the acellerator diaphram. That little thing will shrivel up like a caulifower. I nearly panicked when that happened. The fix was quite simple and I accidently stumbled upon it. I just ran some hot water and washed it with dishwashing liquid for a few minutes and it returned to it's normal shape. WHEW! Make sure you protect your eyes and face when directing the carb cleaner spray into those little orifices and jets. It they are plugged, that stuff will shoot back into your face. Hope this helps.

You da man Boit! Thanks for the info. You have me a bit concerned with the whole puckering accelerator diaphram considering I don't know what that is... But, I guess if I see something shriveling, I'll wash it off. :)


99WR,WR timing,throttle stop removed,Uni filter,E-Series pipe,carbon air box,Pro Tapers,lights removed,YZ tank,13 tooth sprocket

Scott, I'm just an old geezer dude who loves dirt bikes and motocross. That diaphram is located at the bottom of the carb under a little plate with 3 little screws holding it on. It's on the right side(brake lever side) of the carb where the accelerator pump rod goes down thru the carb. If you ever take it off and realize that you don't know which way it goes back in, here's the answer. The diaphram has a small steel rod insert in the middle of it that the accelerator pump rod pushes down on. It's kind of flush against the diaphram on one side but protrudes on the other..about a quarter of an inch or so.The protruding end part of that rod faces downward into the plate. Actually, I could see where the pump rod was making a mark on the insert so that makes it a little bit easier to see how it goes.The diaphram has a little lip on it that fits snugly into the body of the carb. Also, be careful not to lose the tiny little O-ring on the plate. The manual doesn't show this very clearly. Other than getting the cams back into position after adjusting the valve lash, I find the bike pretty easy to work on. The next time I check the valve lash, I'm gonna take my Dremel tool and using an engraving bit, make a small mark on the cam chain right above the punch marks so that I can tell easily where to situate the sprockets instead of relying on hit-or-miss. Hope this helps.


That’s a great idea for marking the timing chain, I wish I’d thought of that. I count the number of links between the marks before I remove the cams and use this number to make sure I have the cams timed correctly with respect to each other. One downside to marking the chain is that you will still have to make sure it is “timed” correctly with respect to the crank (but I’m sure you realize this). Maybe a third mark on the head could help you line up the chain with TDC.

I remember reading a post where someone had a hard time getting the second cam in, was that you? Either way I think putting the chain on both cams and then placing the cams on the head simultaneously is easier.

I first “time” the exhaust cam and then tilt it back up off the head. Holding the chain in place on the exhaust cam with one hand (and keeping tension between chain and crank) I insert the intake cam under the chain with the other, keeping the same number of links between them. Then I tilt both cams back down onto the head.

When you tilt the cams away from the head the sprockets can be held close together, creating plenty of slack to allow them to both fit under the chain. Once the chain is resting inside the teeth of both sprockets there will be enough slack to allow the cams to be put back on the head.

Hope this makes sense…

But I think next time I may try marking my chain as well, it sounds easier than counting the pins.

I used a felt marker (after trying to get it right at least five times)

Thanks Hick and Holeshot. I think making an extra mark on the chain where it would be level with the head is a good idea as an extra sighting index. Hick, even if the crank turns a little, which it will with all the tugging on the chain, it won't rotate more than a few degrees, and I can line everything back up in a second or two once the cams are in the proper place...just a recheck against the crank marks to make sure all is well. I was thinking also that the next time I have the inclination, I'll set up a dial indicator thru the spark plug hole and find true TDC and see if the crank mark lines up properly. That will tell me for sure if the cams are off a little or it the crank mark is not accurate. Either way, the dial indicator method would be the most accurate. I'll try that techniquee of getting both cams under the chain and then tilting them into place next time.Holeshot, I thought about using a laundry mark for the cam chain but then thought it would stick due to the oil on the chain. I suppose I could have used some contact cleaner on a rag and wiped off the chain in that area but I had a brain burp and missed that idea. I always have my bright ideas afterwards.

Originally posted by Boit:

I always have my bright ideas afterwards.

Yeah, me too. What I meant about the chain being “timed” was that if it skipped a tooth on the crank. I let mine come off the crank gear altogether. But it wouldn’t matter if you also marked or just eyeballed the correct TDC position of the marks on your chain relative to the head. So you bend down and peer in that little hole to check crank location, get back to check marks on chain with cylinder head and then install cams. I’m definitely going to try this next time.

I would be surprised if the TDC mark is off, although the timing tab on my old Camaro was off by several degrees when I checked it with a piston stop. Let us know if you find anything interesting.

You guys need to write a book it will save me having to copy and paste all these tips...Maybe when I get a few more I'll post some of these on my web-site if you don't mind.


Hick, I forgot about the chain coming off the crank sprocket in the case and messing up my mark for the cam sprockets. Not that it happened, but it didn't occur to me since I was careful to keep tension on the chain by zip- tying it to the bolt for the gas tank mount. That bolt is long and I just threaded it in a few turns and used it as a hanger. I will be very aware of not letting the chain jump a tooth at the bottom from now on. I suppose we ALL have our little methods for getting these things done as painlessly as possible. This site has been absolutely invaluable for all the information concerning the 426. No doubt it has kept me from making mistakes that could have seriously damaged the bike and possibly have caused me injuries. I hope I can be of help as well to other 426 owners.

[This message has been edited by Boit (edited 10-12-2000).]

Mike, be my guest in using anything I have suggested. Since all my children are now grown and out on their own, I have to improvise at getting things done when I'm alone in the garage at 1am and no extra to assist me. A good assortment of zy-ties is worth their weight in gold to me. I catch myself laughing at some of the ways I'll loop several together to accomplish a 3-handed task, but it works. If I get really frustrated, I'll stop and go beat on a fence post with a ball peen hammer. That relieves my hostility and clears the noggin. My brightest ideas come shortly after that and things start flowing again smoothly. Hey, I'm even getting pretty good at putting on graphics straight and with no bubbles. Go figure.

Change the chain to a good quality one before you even start it.. The yamaha one for 2000 was complete garbage and if you don't you'll be doing sprockets soon after along with a chain.

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