Rebuilding 2001 yz426f


18 replies to this topic
  • YamahaYZ426F

Posted April 09, 2007 - 11:08 AM

#1

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:

  • creeker

Posted April 09, 2007 - 12:03 PM

#2

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.

  • YamahaYZ426F

Posted April 09, 2007 - 01:19 PM

#3

what else are u doing to ur bike

  • creeker

Posted April 09, 2007 - 02:10 PM

#4

03' 450 Exhaust Cam, new cam chain and rebuilding the front and rear fork/shock... not sure what else. You?

  • grayracer513

Posted April 09, 2007 - 02:15 PM

#5

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

  • creeker

Posted April 09, 2007 - 02:33 PM

#6

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


Any particular reason why or just a personal preference?

  • Wiz636

Posted April 09, 2007 - 02:52 PM

#7

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

  • Pozi

Posted April 09, 2007 - 03:07 PM

#8

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.

  • YamahaYZ426F

Posted April 09, 2007 - 04:15 PM

#9

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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  • grayracer513

Posted April 09, 2007 - 04:35 PM

#10

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.

  • creeker

Posted April 09, 2007 - 04:47 PM

#11

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...

  • 642MX

Posted April 09, 2007 - 05:48 PM

#12

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

  • 642MX

Posted April 09, 2007 - 05:54 PM

#13

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:

  • grayracer513

Posted April 09, 2007 - 09:48 PM

#14

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.

  • yama02yz250f

Posted April 09, 2007 - 10:06 PM

#15

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

  • creeker

Posted April 10, 2007 - 02:31 AM

#16

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:

  • creeker

Posted April 10, 2007 - 09:51 AM

#17

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?

  • 642MX

Posted April 10, 2007 - 09:57 AM

#18

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.

  • creeker

Posted April 10, 2007 - 03:11 PM

#19

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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