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YamahaYZ426F

Rebuilding 2001 yz426f

19 posts in this topic

Well i am planning on rebuilding my 2001 yz426f top end this year after the summer and whanted to know what parts would i git like what brand of piston and what rings should i git any sort of advice would help thanks guy :thumbsup:

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I got a Wiesco High Comp Piston Kit from eBay for $128.90 shipped... planning to do a top end rebuild on mine soon as well.

Also got a cometic gasket kit.

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I'd stay with a stock piston and rings myself.

Any particular reason why or just a personal preference?

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I used all oem parts on my rebuild. Buy them through the TT OEM store and you will save a ton of $$$.

I second that. I only use OEM parts from the TT store. Save mega bucks and support the TT community.

I have a brand new still in bag 2001 426 cam chain that I am not using. PM if interested.

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I am going to put new piston and piston rings , hot cams with auot decompriesion, and might git new valves depends on how bad they are and i might rebuild the clucth but i dought i well its seems ok right now. Anyone got any ideas what else i should do to my bike if i am redoing my topend

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Any particular reason why or just a personal preference?
Less expensive, extremely reliable, and for most riding that I do, I wouldn't get enough benefit from the boost in compression to make it worth putting up with the downside, as small as it is.

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Less expensive, extremely reliable, and for most riding that I do, I wouldn't get enough benefit from the boost in compression to make it worth putting up with the downside, as small as it is.

I wasn't aware of any downsides to using the High Comp piston/rings... unless you are saying using the Wiesco is less reliable.

Also, I checked before getting the High Comp kit and the price for OEM versus the High Comp was virtually the same...

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Well i am planning on rebuilding my 2001 yz426f top end this year after the summer and whanted to know what parts would i git like what brand of piston and what rings should i git any sort of advice would help thanks guy :thumbsup:

Here is a list of things...

Wiseco 13.5:1 piston set

valve seals

valve springs

cam chain

mag cover gasket

base/head gasket

tensioner gasket

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I wasn't aware of any downsides to using the High Comp piston/rings... unless you are saying using the Wiesco is less reliable.

Also, I checked before getting the High Comp kit and the price for OEM versus the High Comp was virtually the same...

There are no downsides that I'm aware of. The Wiseco piston is forged, so the piston to cylinder clearance is greater which causes a bit of piston slap, but thats the way they are designed.

I've been using the Wiseco 13.5:1 piston for a couple years with excellent luck. I really like the extra low end power, it helps get my over-weight butt over jumps easier.....:thumbsup:

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I wasn't aware of any downsides to using the High Comp piston/rings... unless you are saying using the Wiesco is less reliable.

Also, I checked before getting the High Comp kit and the price for OEM versus the High Comp was virtually the same...

You can buy the OEM piston and rings for $105, compared to about $170 for the Wiseco.

The OEM pistons usually fit better, and run quieter as a result. Wisecos will occasionally be fit a little loose, and slap as a result. It isn't usually harmful, but it's annoying, and it can't be considered a good thing.

Then there is the increased likelihood of pinging and detonation, which could require you to use race fuel or octane boosters in hot weather, and it will make the bike a wee bit harder to start.

As I said, the downside is small, but in my opinion, so is the gain, and it costs over 50% more than the OEM stuff. If I was building a half-miler, I wouldn't think twice about using one, but for MX, desert, or recreation, I wouldn't think twice about not using one, either.

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man i learn so much from you grayracer...we need a seperate gray racer forum.

LOL, yep! The man sure seems to know his stuff! :thumbsup:

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There are no downsides that I'm aware of. The Wiseco piston is forged, so the piston to cylinder clearance is greater which causes a bit of piston slap, but thats the way they are designed.

I've been using the Wiseco 13.5:1 piston for a couple years with excellent luck. I really like the extra low end power, it helps get my over-weight butt over jumps easier.....:thumbsup:

Did you have to change to "race fuel" or just use 93 pump gas?

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Did you have to change to "race fuel" or just use 93 pump gas?

I've always ran race fuel, even before the hi-comp piston. But, it will run on pump gas. Kawasaki 's come from the factory with a 13.5:1 compression ratio and only require pump fuel.

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I've always ran race fuel, even before the hi-comp piston. But, it will run on pump gas. Kawasaki 's come from the factory with a 13.5:1 compression ratio and only require pump fuel.

Thanks! I thought it seemed odd that a Yamaha running a 13.5:1 would require race gas, but a Kawi wouldn't that comes stock with the 13.5:1...

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