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Post by bigmac on Apr 3, 2013 23:25:52 GMT -5
On a 50cc Chinese scooter with a 139QMB engine, what's the valve clearance set to when it's new from the factory?
I vaguely recall hearing .002 for both the intake and exhaust, but that sounds kind of tight to me. Everyone seems to have his or her own preference for setting the valves, but I'm curious to know what the factory set clearance is suppose to be.
This question might also depend too on the brand and year of manufacture, in my case, a 2010 Roketa.
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Post by gatekeeper on Apr 3, 2013 23:59:22 GMT -5
In one of the owner's manuals I have it says .002 inches. I set mine to .004 inches because it seems to run better.
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Post by indymoped on Apr 4, 2013 8:02:24 GMT -5
DX I set my intake to .004" and exhaust to .005" and it runs great. "Factory" setting is a poor term when talking about Chinese built stuff. As long as it works good enough to send it off and sell it they don't care. They're about quantity not quality. Lol
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Post by millsc on Apr 4, 2013 8:18:43 GMT -5
the manual i got with mine had all kind of words spelled wrong, quite funny to read i read it for laughs  |
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Post by carasdad on Apr 4, 2013 8:42:24 GMT -5
When I was selling scoots.. .002 was commonly how they came and once warmed up they lost power. About 50% of them came set at .000 yup...they were tight against the valve stem and would not even start..or if they did they did not run right from the 'git go' At my repair/parts shop I set them all at .004 intake .005 exhaust and have yet to see a customer lose power when the scoot warms up.  In my opinion they just assemble the engine...and I doubt they set valve lash from the factory  |
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Post by devo344a on Apr 4, 2013 10:23:38 GMT -5
just did mine at .004 and it runs fine
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Post by bigmac on Apr 4, 2013 23:33:49 GMT -5
Alright, so .002 seems to be the standard (at least in a manual), but many find that setting to be too tight.
I do think this is a bit odd though. I'd imagine the engineers who designed this engine would've determined the most suitable valve clearance so factories would know what its workers should set (or at least try to set) the valves to.
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