Power valve o rings?
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Where do the o rings fit, the orange ones? Also is there a gasket? Whoever built my engine last even had a black o ring sandwiched in. I really need a schematic or iTunes vid on how to reassemble the PV. I have the fixed PV with diamond end. It’s a 3bn engine with a 3mb barrel and head...
Ta! -
That’s utube not iTunes! Ducking spellcheck!
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You don't need a video to know how to disassemble it. It's like 5 pieces.
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I don’t know where the seal fit is all. Putting it together and in is no problem. I just don’t think it was correct when I took it out..
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Or are the orange seals for servo PVs only?...
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No 19 are the seals. They sit in the bushes.
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The kickstart side is straightforward, simple groove that fits perfectly. It’s the gearchange side that has no groove or place for a seal. The previous owner had the orange one just flopping around and a black smaller o ring squashed flat between the bush and the cover. Neither of those two are affecting a seal. I’ll check and see if there’s a paper gasket for that side. That would be enough of a seal...
It’s frustrating when the last owner didn’t know what they were doing, it makes reassembly a bear!... -
The pictures are a give away.
The bush there has a groove cut out of it, the O-Ring sits inside the groove, the bush secures to powervalve in place.
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Sorry bud? Pics? I get a link with ‘all text’ access denied.
Neither my bush or the cover have oring grooves on them, on that side. I wish I could post pics to show you what I mean but I just have a phone. -
@SpookDog Oh Yeah
How annoying.Sorry, it looks like they are blocking that resource.
It's a parts diagram showing you where the O-Rings go.
https://www.fowlersparts.co.uk/main/img/assemblies/large/e2bbdd33f448b949dadded717beb407f.png?6
I'll get it hosted elsewhere and link it in.
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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! -
The bushes wear out.
There were different types of powervalves, not sure how they differed on the bush side of things though.
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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. -
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?... -
@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.
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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
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Thermostat is paper gasket IIRC. Kellogs Cereal will do.
Always Originate, Never Pirate!
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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 ...
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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...
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@Calum there is an o-ring under the thermostat itself with the gasket above that
