how to tell what year a 426 motor is?

I have a 02 426 and  im looking at a used 426  motor to buy but for a build project, its not in the bike and the guy is not sure what year it is. Any way to identify the year of this thing from outer markings? Asked the local yamaha dealer they said no way to tell if its not in the frame

Edited by bikejunkie2003

I'm not aware of any external physical distinctions, and apparently, the engine numbers are useless for tracking anything because nobody knows what they indicate.

 

But, if you open the drive side up, you can remove the nut holding the crank gear and see if the gear is splined, which would make it an '01-'02, or anchored by a single key slot.  The 2000 was keyed, the later ones weren't.

 

Something to be aware of:  A 426 cylinder can be installed on a YZ400 with the right mix of parts, but it's a different engine underneath that.

I'm not aware of any external physical distinctions, and apparently, the engine numbers are useless for tracking anything because nobody knows what they indicate.

 

But, if you open the drive side up, you can remove the nut holding the crank gear and see if the gear is splined, which would make it an '01-'02, or anchored by a single key slot.  The 2000 was keyed, the later ones weren't.

 

Something to be aware of:  A 426 cylinder can be installed on a YZ400 with the right mix of parts, but it's a different engine underneath that.

thanks thats good to know!!!!! anything i can do to tell if thats what  im looking at?

The cylinder has the size of the engine it was built for cast into the lower front corner. 

 

The 426 used clutch components that were considerably larger than the 400, and the right side cover is clue as to that.  The 426 clutch cover is nearly identical to those on the 450's, while the 400 is distinctly smaller.  Here again, though, the 426 right side cover can be bolted onto a 400, so fraud is still possible.

 

A good way to see the differences is to take a look through the different picture threads listed in the forum index.

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