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Post by gitsum on May 3, 2013 18:31:24 GMT -5
I think most generic GY6 157QMJ engines are usually both exhaust and intake around .004"
This is a made by SYM engine and most of their GY6 based engines are usually both .002".
I checked the valve clearances at 400 miles and the intake was .003" and the exhaust was slightly less than .002" (obviously a little tight). So I'm leaning towards .002" as the correct spec. I set them both to .003" to be safe and just a tiny bit of valve clatter for a few seconds until it reaches operating temperature, it seems to run just fine.
Nothing in the owners manual and nothing on any of the stickers on the scooter about valve clearance specs. I searched for a service manual to download and couldn't find one.
Does anyone know the actual factory specs for the valve clearances on a 2012 Tomos Nitro 150 (157QMJ made by SYM)?
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Post by domindart on May 3, 2013 19:36:11 GMT -5
I own a 2009. Never messed w valves yet... odd that you have to do this on a 2012 now. Where can I get a manual for this ride? Oh welcome to the site.  |
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Post by gitsum on May 3, 2013 23:47:40 GMT -5
[replyingto=domindart]domindart[/replyingto]It is standard maintenance to adjust the valves on a GY6 (or just about any scooter or motorcycle) after a break-in period. The Tomos Nitro 150 engine is actually made by SYM
and very high quality.
The valves on most SYM engines don't need much attention, but it's still not a bad idea to check. I believe my exhaust was a wee bit tight and my intake just a wee bit loose. It still ran fine and the valve clearances probably wouldn't have changed much more over the next 5000 miles or so.
If the tolerances are off a little the engine will still run pretty good, but it can compromise maximum performance and fuel economy.
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Post by gitsum on May 4, 2013 0:54:12 GMT -5
Hmmm, been doing a little more research. Still can't find any valve clearance specs or a service manual. But the Lance Cali Classic 125, SYM Allo 150 and SYM Fiddle II 125 have similar engines and the valve clearance specs on all three for both intake and exhaust are .12mm (.0047").
So that has me wondering if the tolerances on my Nitro 150 were actually getting pretty tight? But then on the other hand it seems those other SYM engines don't really have the valves needing much adjustment?
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Post by domindart on May 5, 2013 16:35:55 GMT -5
free bump as I would like to know too since I have the same bike !
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Post by gitsum on May 8, 2013 17:14:24 GMT -5
[replyingto=domindart]domindart[/replyingto]I adjusted the valves again to .004" intake and .005" exhaust.
It seems to run the same as .003", so I guess I'll just stick with the slightly looser tolerances.
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Post by hank on May 8, 2013 17:21:21 GMT -5
Hi Anywheres from .002 to .005 are acceptable its up to your personal preference and the performance of the engine as to where you set them On my 4t  cc bbk scoot i use .003 int .005 ex with excellent results Take care and ride safely Yours Hank |
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Post by gitsum on May 9, 2013 10:57:28 GMT -5
That's the same conclusion I came to, but it's nice to have some confirmation ;D
Thanks for the info.
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Post by gitsum on May 9, 2013 18:43:30 GMT -5
[replyingto=gitsum]gitsum[/replyingto]OK, not knowing what the official valve clearance specs are for the Tomos Nitro 150 isn't important.
.004 IN and .005 EX is the best setting, period. Took on a nice little ride including some 55 mph roads and the engine was purring along smoother and a little quieter than before. Maybe just a slight increase in power, not much, but I'm convinced it won't get any better than it is now. You can tell it is really in that "sweet spot".
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cc bbk scoot i use .003 int .005 ex with excellent results