Yamaha part numbers -- WR400 -> 426 Conversion


I'm doing a 426 conversion on my 400 and i got a quote for all the bits using new OEM stuff from a 2001 WR426. One thing i noticed with JJHayesIII's list of part numbers he has posted a few times on the forum is that the part numbers for the piston & crankshaft assembly are different. Which after checking the catalog his parts were for a 2002 model.

Here are the part numbers:

Crankshaft Assembly

2001 WR426: 5JG-11400-10-00

2002 WR426: 5JG-11400-20-00


2001 WR426: 5NG-11631-00-00

2002 WR426: 5NG-11631-10-00

So my question is. What is that 3rd number for? are these parts actually different. Does anyone know of any changes that would have affected these parts between 2001 & 2002.

Just wanna make 100% sure before I order the parts


Phillip Savage

I don't know the answer for sure, but the assumption I made going in was that it was just an updated part, so sometimes when you try to order the 2001 part #, they'll automatically replace it with the 2002 #, since it was originally the same part, but has been revised....

After going through the part numbers for 2001 vs 2002 426's for parts ill be ordering the only ones with different PN's are the crankshaft & piston which JJHayes has confirmed work ok for the 400-426 conversion, so i guess ill use the updated part numbers :bonk:

Thanks for the help guys

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