Powervalve Diameter

[huggy76]

Hi all

I am trying to find out the diameter of a known good powervalve where the bush fits if anyone could measure one for me please?

I have stripped the top end of my engine today and am trying to decide what I need to do with the powervalves as they were leaking badly. I was expecting them to be showing lots of wear but they look really good so maybe I just need bushes??

Thanks in advance for any help
Andy

[steve99]

I am in the same position with my rebuild. What I would say is try new bushes and see how they fit. Mine needs just bushes thankfully. Yours maybe the same

[urbantangleweed]

Get a set of genuine Yamaha bushes from Norbo and see how they fit your valves, this is the best way to determine if your valves are still serviceable.

[huggy76]

I’ve had a bit more of a measure today, the outer end that tends not up wear too much is 17mm but the inner ends are both under 16.5mm. Very tempted to get new valves and bushes to almost future proof it.
Next question would be, if I go that way, are genuine or after market ones better, I like the look of Mutts ones but would appreciate any feedback people have.
Has anyone used the Mad Biker Designs centre bushes?