2001 yz426f valve help!

hello thumper talk people! i am brand new to 4 stroke engines. i just got a 2001 yz426f. it has low compression when i bought it and needs the shims replaced. i knew this coming in. but all i traded the guy was a xbox and a tv. so i thought i would just take a chance. lol. so i looked up videos and got the manual and everything and know the clearance for the valves and mostly know how to do it. so what i am asking are what shims do i need to buy? where is the best place to get them and what is a good price for them? or just tell me some helpful information about this bike! thanks!

I actually just shimmed a 01 yz426 with my buddy this past Friday. I just traded him the shims that were in the bike for some out of my shim kit. It's the Hot Cams shim kit

I accidentally hit send on that. You'll have to measure the valves and pull out the shims that are in the bike before you can determine what size shims need to be installed in the bike.

Would it just be better to take it to a bike shop and have them take care of it? Or would they try to make me pay an arm and a leg for it?

I do all of my maintenance and repair on everything I own myself. Shimming valves are pretty easy in my opinion.

I'm just pretty new to 4 strokes. I have seen plenty of videos and online stuff and in the manual I've read a lot. I'm just not sure on the exact measurments on what I need them to be. There are a lot of measurments that look like the ones I need but not sure. Do you know what it exactly is called? I think it's the cam shaft to cap clearance but again I'm new to this. Lol.

Do you have a manual for the bike? If not you can download one here at yamaha-australia.com here is a link: http://www.yamahaownershandbook.com.au/index.php


Shimming isn't a hard think to learn. A shop might only charge you 40 bucks to do it. But if they see anything in the engine they might twist your arm to do more work than is necessary and that adds up quick. 

Read through the manual and it should give you a step by step instruction on replacing the shims. plus there are tons of guys on TT willing to help you through the steps. There are many tricks so that you dont have to deal with re-timing the engine ever time you shim the valves.


First you will measure the clearance. If the clearance is off you will need to pull the shims and measure them. You then could calculate what size shim you need to install. For example, if your clearance is .01 and it needs to be .10 you will buy a shim that is .09 smaller than what you took out.


A hotcams shim kit is around 75 bucks and comes with a bunch of difference sizes that are usable on many different bikes. If you don't plan on doing valve work in the future it is probably cheaper to buy individual shims.


the parts department at most dealers will sell you individual shims for 4 or 5 bucks which i think is a rip-off. The cheapest way to buy replacement shims is to buy the proX brand shims at rockymountainatvmc.com for 2 bucks a piece. 

your manual should have a table in it that tells you what shim you need given the clearnce and the shim currently being used

I also need a new bolt for the oil filter cap. Where do you think I can get one of those at?

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