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Tuning a w8 carb ?


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On my pa 125 its running lumpy at one and a half turns out from all the wayn in.( Recomended from pap ) But if i turn it only one full turn out it runs realy smooth, and even ticks over better. Am i in danger of seizing the engine, as i know on the w8 it only adjusts the top end.

The spark plug colour seems ok at this setting, but odviousley dont want to take any chances of a seize.

Thanks Clive

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My Top 80 with the W8 is the same - runs much better at 1 to 1 1/4 turns out. From what I can gather this is completely normal and all motors will tune at a different point. You can only adjust the low speed mixture screw on the W8 and the motor doesn't work hard enough to be able to seize it at low revs. The main jet on these is fixed and controls the mixture at high rpm, although he low mixture screw will apparently have a minor effect.

If you do a plug chop at high revs just to make sure you have a nice browny sooty plug at high revs then all should be well. Just adjust the bottom end to run as cleanly as possible. (My Top 80 runs like a pig with book settings).

Lean the motor off until it won't pick up cleanly when blipping throttle, then enrichen 1/8th turn at a time until you get a clean pick-up. If it is too rich, tick over revs will drop and it will 4 stroke - go lumpy and brup bruppy!

Make sure you don't have any major problems first like air leaks (though unlikely as this would make it leaner). And if it explodes - I'm not paying for it - disclaimer!


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Steves description is spot on, what we do on our wg8's is to increase the idle to a fast tick over whilst tuning as this smooths out the engine and you can more easerly hear the best rpm, once found you can the lower the tick over again and back off the low end screw a little to help the throttle pick up response.


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