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08-10-2013, 05:45 PM | #1 |
Join Date: Jul 2012
Location: NE oHIo
Posts: 160
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150cc BMS valve problem
Well I was looking at the Head/valve cover gasket today on my 08 BMS:
to see if it was like the one on my 07 Xingyue. Was different, probably the correct one. Well I'd done a compression check to find there was no compresion. Tried the wiggle test for valve clearance, and the intake was really loose. Took a look down the intake port to find it'd dropped a intake seat. What typically happens in this case? Think it'll need a total rebuild? Soon as I finish up the Xingyue I'll be pulling this one apart.
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1981 C70 honda 2007 Xingyue ita 150t(X2) 1976 Vespa Bravo(2) 1980 Vespa Ciao 1967 Sears Allstate Do I continue? "Freedom is just another word for nothin' left to lose." Janis Joplin 1943-1970 |
08-19-2013, 09:07 AM | #2 |
Join Date: Jul 2011
Location: Connecticut
Posts: 493
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set the top valve (intake) to EXACTLY .004" and the bottom to .005" inches. "wiggle test" is completely inaccurate, and should not be used to denote proper valve rocker lash.
In the case of the "dropped seat", replace the entire head with an assembled new head and new head gasket, but be sure to clean the top of the jug with a light abrasive (cookie wheel) and check the top of jug with a machinist straight edge. Chances are, that you may have ring or other inner cylinder damages as well if you have no compression. So in reality, the safest bet is an entire new top-end. (if you are daring, now is the time for a BBK)
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2011 Roketa MC-23-150 4T 150cc 157 qmj 24mm carb w 115 main jet and paper cone air filter Manual petcock w Tygon fuel lines Scrappy Dog Scooters Retro-slash stainless straight-thru exhaust RED spring clutch Adjustable CDI (brand unknown, it's blue and red and works great!) KOSO high performance variator w 12g sliders Gates Powerlink 835-20-30 belt GPS verified 65mph on flats. |
08-19-2013, 08:36 PM | #3 |
Join Date: Jan 2010
Posts: 139
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I hope you don't run with the engine shroud removed like the pictures. That can cause your valve seats to drop out along with other problems. The shroud is needed to direct cooling air around the engine and without it your engine will be toast in short order.
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08-20-2013, 08:08 AM | #4 |
Join Date: Jul 2011
Location: Connecticut
Posts: 493
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Good point Qwerty, NEVER run your engine without the cooling shroud.
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2011 Roketa MC-23-150 4T 150cc 157 qmj 24mm carb w 115 main jet and paper cone air filter Manual petcock w Tygon fuel lines Scrappy Dog Scooters Retro-slash stainless straight-thru exhaust RED spring clutch Adjustable CDI (brand unknown, it's blue and red and works great!) KOSO high performance variator w 12g sliders Gates Powerlink 835-20-30 belt GPS verified 65mph on flats. |
08-22-2013, 08:00 AM | #5 |
Join Date: Jul 2012
Location: NE oHIo
Posts: 160
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Engine cooling
Well as for he shroud that's the way I bought it. The PO was going to "fix" it, took it apart, decided it was beyond his abilities(I guess), put it in the corner of his garage, and bought another one. Then listed this on on craigslist, and I bought it.
As for valve clearance, a quick wiggle of the rockers can tell alot. When I wiggle the rocker and it has 1/2" of clearance there is a problem. I set the valves on my Xingyue using the wiggle test, then checked the clearance with a feeler and it was just right(.004" on the intake, .005" on the exhaust)believe it or not. No brag, just fact. The correct clearance can actually be calculated via turns on the screw(threds per inch times amount of turns, or in this case amount of turn being about a quarter of a turn for .004", and one third of a turn for .005"). After setting the clearance, usually I do verify with a feeler gauge.
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1981 C70 honda 2007 Xingyue ita 150t(X2) 1976 Vespa Bravo(2) 1980 Vespa Ciao 1967 Sears Allstate Do I continue? "Freedom is just another word for nothin' left to lose." Janis Joplin 1943-1970 |
08-22-2013, 09:08 AM | #6 |
Join Date: Jul 2011
Location: Connecticut
Posts: 493
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Okies. I just use the feeler gauges to begin with, as I see no point to doing additional redundant work, but whatever floats your boat man.
But 1/2" is really bad, your head is smoked at that point (these gy6 heads aren't very good quality). I suggest checking the low end as well, as if this damage occurred while the bike was running it could very likely have damaged the low end as well.
__________________
2011 Roketa MC-23-150 4T 150cc 157 qmj 24mm carb w 115 main jet and paper cone air filter Manual petcock w Tygon fuel lines Scrappy Dog Scooters Retro-slash stainless straight-thru exhaust RED spring clutch Adjustable CDI (brand unknown, it's blue and red and works great!) KOSO high performance variator w 12g sliders Gates Powerlink 835-20-30 belt GPS verified 65mph on flats. |
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