Villiers 150cc Lightweight - valve grinding/adjustment

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IanC
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Joined: 19/05/2021 - 19:40
Villiers 150cc Lightweight - valve grinding/adjustment

I've got a problem where the plug keeps fouling, with a black/oily residue.

I thought it was running too rich, so replaced all the jets and needles etc in the carb, lowered the slide needle to it's lowest, and ran without the gauze air filter. But it's still doing it (maybe not so often).

I read somewhere that a lot of problems with these engines can be due to the valves (clearances or grinding needed?).

Can anyone please explain how to grind and set the clearances? I've seen the fiche but don't see any way of adjusting. I'm more used to adjustable tappets or shims on motorcycles! Or am I barking up the wrong tree? The piston doesn't appear too slack in the bore, so I don't think it's letting oil past the rings.

Apologies if this question is answered somewhere, I have tried searching first - honest!

Thanks!

BTW what's the recommended oil for these mesh/wire-wool type air filters? Seems to me that SAE30 would be too thick - maybe I should thin it?

wristpin
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Joined: 23/05/2012 - 22:09
Your issue is more likely to

Your issue is more likely to be the result of worn valve stems and guides rather than valve sealing. Valve clearance ( assuming that they are too tight) is achieved by the removal of metal from the end of the stem, either by grinding or careful filing.  It may be worth checking the condition of the crankcase breather, a ball and sponge installed between the valve chest and the magneto backplate. Correct operation of the breather maintains a negative pressure in crankcase which helps in keeping the engine oil tight. Tappet clearances are shown as 2-6 thou” for both valves.

The recommended engine oil of the day was Castrol XL SAE 20W-50 and the air cleaner maintenance was, wash, dry, immerse in engine oil and allow to drain before refitting .

DJD
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To grind the end of the valve

To grind the end of the valve accurately, I used my pillar drill to make a hole that gave the valve a snug fit into the small 2" X 2" block of pine. With valve sticking out a few thous, I simply rubbed it back and forth on my oilstone, not grinder.Doesn't take very long.

IanC
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Joined: 19/05/2021 - 19:40
Thanks all, I'll take a look

Thanks all, I'll take a look next week, breather first stop.

Oil leakage around the guides makes more sense than leaking valves. Are the guides replaceable?

wristpin
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Yes, the guides can be

Yes, the guides can be replaced but whether they are still available is questionable. Try Paul Child at Meetens.  Bear in mind that there will be wear in both the valve stems and the guides.