Power Valves.

[philmill]

Hi Guys, so I dug out the bushes etc got the valves today but I'm not sure about using them, the outer parts look well worn to me, are these ok or not?? hopefully you can see the wear in the pics.

Thanks, Phil

EBVQ4t0aQQOgvGQRbSkr9Q by Philip Millard, on Flickr30qDkd7LSseZ7H1s3EMZfg by Philip Millard, on Flickr

[kostas]

I think your bushes have been machined and fitted with internal bushings in the past.

Most probably your PVs are machined to match also..

Maybe I’m wrong.. won’t be the first time!

[Shytalk]

What does the fit feel like? if its not too loose then they will be fine, from your post - do you mean that you've got new power valves?

[philmill]

Thanks for the replies, no, i do not have new ones. These look like they have been rubbing and are thin.

Can I vapour blast the actual valve units??

Phil

[Shytalk]

Jan 29, 2019 20:10:39 GMT 1 philmill said:

Thanks for the replies, no, i do not have new ones. These look like they have been rubbing and are thin.

Can I vapour blast the actual valve units??

Phil

Course you can, most just put them on a polishing wheel and clean them up

[Mr Kipling]

you most certainly can...

[philmill]

Anybody tried the valves that Legend M/C's sell? I'm a bit worried after trying their clutch arm bearing upgrade which didnt fit....

Phil

[huggy76]

I wouldn't use them, the groove where the locating plate sits is very worn by the look of it and that will let them move more and only lead to premature wear in the bushes.

[stusco]

Use Norbos thicker retainers

[muttsnuts]

you need new bushes/bearings Phil, still available from Yamaha or Norbo does them, don't replace the valves themselves as they have been matched to your ports now !

[philmill]

Cheers, Dave, the valves all look good so no issue there.

Phil

[bare]

Best get yer Micrometer out .

[philmill]

Jan 29, 2019 22:19:44 GMT 1 bare said:

Best get yer Micrometer out .

Thanks, can anybody tell me what the size should be? and I will check them.

Phil

[icarus001]

I don't have as much experience as the regular engine builders in here, but I've rarely found worn bushes that were a problem, the actual Yamaha powervalve seems to be made from something softer than the OEM bushes, so that tends to wear before the bush. Whenever the valves were loose it was always the valve itself that I found worn.

I'm sure I posted on another thread about various options, but recently I just decided to buy new OEM valves/bushes while they're still available - for both valves, bushes and seals it was about £300, but they should last me a lifetime with the small amount of miles I do. I was tempted to knock up new bushes on the lathe, trying a softer material, but in the end I couldn't be bothered. I might try it one day when I've got more time.