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Tyson Wall

2002 426 crank in 400

4 posts in this topic

I know this has been coverd but was unable to find the info I needed about the counterbalancer gear diffrence on the 2000 and the 2001-2002. counterbalancer gear is driven by a key on the 400 and 2000 426, and splines on 01 and 02 426, so if I purchased the counter balence from a 2002 with the splines and a 2002 crank would this fit in my 99 YZ400f? I would be purchasing a 426F Cylinder and crank barrings and gasget. Any thing else I would need?

Thanks for your help

Edited by Tyson Wall

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I'm halfway through turning my 99' WR400 into a 426. I used a 2000 yz 426 crank and only had to provide my machinist with the correct gear for the splinned vs keyed crank. Other than that all the main bearings and gaskets from the WR400 kit were the same. Had to use a 426 head gasket of course. I choose to sleeve the 400 cylinder since all the used 426 cylinders were in bad shape that I found. From everything i've read on this forum the 400 vs 426 heads are pretty similar and the 400 head will work on the 426 cylinder. Top end should be finished in a few days. No issues yet with the top end. Fingers crossed.

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I'm halfway through turning my 99' WR400 into a 426. I used a 2000 yz 426 crank and only had to provide my machinist with the correct gear for the splinned vs keyed crank. Other than that all the main bearings and gaskets from the WR400 kit were the same. Had to use a 426 head gasket of course. I choose to sleeve the 400 cylinder since all the used 426 cylinders were in bad shape that I found. From everything i've read on this forum the 400 vs 426 heads are pretty similar and the 400 head will work on the 426 cylinder. Top end should be finished in a few days. No issues yet with the top end. Fingers crossed.

Thanks for the reply! Just the info I was searching for. I can get a brand new 426 crank assy for $297 from yamaha but not sure what year crank it is. Here is the part number 5JG-11400-20-00 CRANKSHAFT ASSY. I am also asuming that would come with the rod too.

Thanks for your help

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The OEM 2000 YZ426 crank I received was complete and ready to go. The only part needed for the bottom end was the drive gear that fit on the splinned crank. I don't know the part number because I was given two gears from different year 426 motors from a local cycle salvage shop. Which would lead me to believe there was little or no change in that part in thew 426 motors. Waiting for the top end to be finished to see if I will need to re-jet. Most of the wr426 i've seen on here in my elevation range are running something close to a 170 main and 45 pilot. BTW my machinist claimed he had NO ISSUE'S at all with the 426 crank in the 99' wr400 bottom end.

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