Power valve o rings?

[SpookDog]

Fowler’s don’t like hotlinking apparently!
I found the diagram, unfortunately it is different from what I have fitted. I found I can affect a seal if I slip the oring over the end cap. Without it the whole cap/bush is very loose. It slops around loads! Whereas the other side is a good fit.
I wasn’t even sure if it was original to the barrel. Who knows what butchery was done before. The PV has 3bn on it I think, yet the barrel is 3mb. I don’t know if there’s a difference. I’m still fumbling around in the dark. The only other 2strokes I’ve worked on were air cooled, ts er’s, and more shedloads of Vespa & Lambretta’s than I can recall. I don’t recall them having an oring between them
Cheers bud!

[Calum]

The bushes wear out.

There were different types of powervalves, not sure how they differed on the bush side of things though.

[SpookDog]

One more question! Do you know what the black oring is for? I’ve got a full gasket set with black oring, but the only black oring I found was squashed into the PV and is obviously not right.
It’s about 3/4 inch.

[SpookDog]

Sorry, was busy thumb typing on a tiny screen!🤪
It’s not just the bush, the end cap it fits into also seems small. Plus it’s fixed, doesn’t move...
I’m guessing that the 3mb was a later servo operated valve? Totally different end cap on that side?...

[Calum]

@SpookDog the markings on the powervalve are misleading. I can't remember what is on the 3mb barrel. I do know that the two barrels take different valves, but I don't think the codes are representative.

[Nottsbiker]

Dont do what I did when I was being stupid and try and fit the o-rings onto the power valve itself lol

They go into the end caps and there is also an orange seal for the pulley end as well

I also got a black o-ring in my Athena gasket kit from PJME and have no idea where it goes

Wish it was the thermostat one as I need one but its the wrong size

[Calum]

Thermostat is paper gasket IIRC. Kellogs Cereal will do.

[SpookDog]

Same as in my gasket set, it’s to small. You need a 33mm one for the thermostat. Get one from eBay. If you don’t have an account someone here will probably order it for you. It’ll be pennies ...

[SpookDog]

Sorry it’s 27mm Inner Diametre X 2.5 or 3mm Cross Section.

Calum, cheers for the info bud, it puts my mind to rest. I always worry more when learning a new engine...

[Nottsbiker]

@Calum there is an o-ring under the thermostat itself with the gasket above that

[SpookDog]

The small oring in the gasket set is for the metal coolant pipe. It goes on the end that mates to the pump. Mysteries solved!...

[Calum]

Hhmm, yeah it's been such a long time since I've worked on that engine

[SpookDog]

Hey! You weren’t wrong, there is a paper gasket. I was wrong about the oring though. It’s to big for the coolant pipe