[Quicklimegirl]

A friend of mine who's a great guy but a real pack rat, gave me this top end a few years ago. He said he thought it was a Yamaha...if so it'd be a pretty early YZ400. I may be mistaken, I'm fairly certain they were first to have reed intakes, and it's got a big reed cage port.
The casting numbers at the base of the cylinder read 397cc on one side, and 51000 and the other. What really puzzled me was this: check out the weird circular smaller port above the exhaust poor. WTF is up with that? Can anyone here identify this positively?

Edited by - Quicklimegirl on Jan 09 2007 06:18:44 AM

 

[UngaWunga]

Decompression port of some sort.

 

[350Four]

It looks like it threaded down deep...could that be a compression release port?

 

[350Four]

didn't mean to be repetitive...just didn't scroll down far enough.

 

[joe c]

you can try over on the thumper talk board. weve had great luck with those guys. super nice and full of info. thumpertalk.com


jc