Help! yz426 or yz400.So confused.

Today i bought what was suppose to b a 2000 yz426f. Well the serial on the frame reads that its a 2003 frame. The cylinder on the engine of this bike says 399cm same as my 99 yz400. WTH!!!!! Can anybody tell me what ive got myself into? :banghead:

A mess!!

the engines r the same right? just diffarent bore right?

Pretty much there are some differences in the clutch, the way the balancer drive gear aligns, the bore diameter obviously and the wrist pins are different, not much performance wise if its tuned correctly.

Do you have any pics of this cause I'm wondering how the oiling system is working. Is there a dip stick in the frame?

Edited by four-twenty-sixer

I googled the frame vin and said it was infact a 426 vin. I dont get it. And its a 2003. They didnt make a 426 in 03. It went to a 450. Yes dipstick is in the frame in front of the fuel tank.

What are the first 11 characters of the VIN number?

No, the engines are not the same. They interchange with each other, and you can mix some of the parts, but if you bought a bike as a 2000 YZ426, and it has a 400cc engine and the wrong year frame, I'd say you have a pile of parts with a title that doesn't match anything on the bike.


Well, I don't know where you googled the VIN, but the tenth character is the year model, and it's a "Y", which means that the frame is a 2000 model. The rest of it the model, etc..

However, it has a YZ or WR400 engine in it, so you have been cheated on that level at least.

Ok i ran the vin through my local yamaha shop. Turns out what was spos to b a 2000 yz426 is actually a 2000 wr400f.

Really. Well that cheers me up a lil. The # on the top of the crankcase reads h309e-009148

Is it possible somebody has put a bored out yz 400 cylinder on this bike?

Possible, but doubtful.

I ran the vin number throught my local yamaha shop and it said that it was a 2000 wr400f. Its not what i was wanting but its still a good bike. Im gonna fix it up and make some money off of it. The valves r out of adjustment and has a massive amount of coolant in the engine oil. I did a comp test and i have 82 psi with throttle wide open. When i turn the engine over by hand I can hear compression blowing back into the airbox. Im not sure where the coolant is coming from. The guy i got the bike from said he just put a waterpump seal in it and then it started getting coolant in the engine oil. Im note sure of valve clearences. where should i start with the coolant in the oil prob?

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