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Post by Fox on Nov 4, 2011 20:54:56 GMT -5
It will tell you that maybe you can run a long vent tube up the frame to the rear of the scooter and then back down to the rear splash guard and that the oil won't run uphill but the fumes will go away without staining the scooter. I did it to this scooter:   |
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Post by usmcdoc on Nov 4, 2011 23:29:33 GMT -5
But won't I still lose oil?  |
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Post by 90GTVert on Nov 5, 2011 7:00:50 GMT -5
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Post by usmcdoc on Nov 5, 2011 9:42:53 GMT -5
90GTVERT....tx bud....but I must have some serious crankcase pressure probs....cause it will blow a quart of oil(til engine is dry)...in about a 5 mile trip. I was told the Cam Stopper plate in the engine causes many problems if you turn engine backwards to align timing marks....it will cause the exhaust valve to remain open...giving you a false reading with your feeler gauges....allowing it to stay slightly open and create pressure under the valve cover. Does this sound plausible and logical to you? I have worked on MANY gy6 50 and 150 engines....and this is the first time I have ever seen a cam stopper plate. I wonder what the hell they made a setup like that?... :banghead:
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Post by 90GTVert on Nov 5, 2011 12:29:36 GMT -5
I have never seen one in person, but I have read about them. Same you heard it seems. You must turn the engine clockwise to TDC, not counterclockwise at all. Not even to fine adjust it on the marks. You must turn completely clockwise to get to TDC when adjusting the valves or valve adjustments will be wrong.
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Post by stepthrutuner on Nov 5, 2011 12:48:57 GMT -5
90GTVERT....tx bud....but I must have some serious crankcase pressure probs....cause it will blow a quart of oil(til engine is dry)...in about a 5 mile trip. I was told the Cam Stopper plate in the engine causes many problems if you turn engine backwards to align timing marks....it will cause the exhaust valve to remain open...giving you a false reading with your feeler gauges....allowing it to stay slightly open and create pressure under the valve cover. Does this sound plausible and logical to you? I have worked on MANY gy6 50 and 150 engines....and this is the first time I have ever seen a cam stopper plate. I wonder what the hell they made a setup like that?...  I think it's purpose is to keep the chain from jumping a tooth on one of the sprockets should the engine kick back on starting or stopping. Seems I've seen this discussion somewhere before but can't remember all the particulars. Don't know why some have it and others don't? I'm sure someone will fully educate us here. |
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Post by usmcdoc on Nov 5, 2011 14:05:41 GMT -5
tx all... Just now looked at it and it seems the cam plate stopper may be the culprit....as the exhaust valve opens as normal....yet remains partially open through 1/2 of the cam revolution...in fact even when the intake valve is open. Should there ever be a time during the engines cycle that both valves should be open at the same time? I understand 4 strokes well....yet have never seen where both valves would be open at the same time... :swear:
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Post by 90GTVert on Nov 5, 2011 14:29:40 GMT -5
4 cycle = Intake, Compression, Power, Exhaust
At the end of the 4 cylces, as another set is beginning, the intake and exhaust valves overlap at TDC. The piston is coming up in the bore, forcing out exhaust... but the intake valve needs to be open when the piston starts moving down. Valves can't (or shouldn't) just slam shut on their seats without taking some time and they can't open with too much immediacy either without stressing things. This little bit of overlap, with the ex valve still open a bit and the intake valve opening also has a scavenging effect, helping to draw the intake charge into the cylinder.
Now if the valves are both open long at the same time, something's wrong. The exhaust valve should not be open for half of the cam's revolution.
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Post by usmcdoc on Nov 5, 2011 19:26:38 GMT -5
Just outta curiosity....when all the oil blew out over 5 miles(and I was unaware of it until I stopped) If the rings wore....would that allow some sort of blow by into the head causing the oil to blow out the vent hole each time I fill it?...Power seems down as well. Valves are both set at .004 so I know that is ok.
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Post by 90GTVert on Nov 5, 2011 19:41:07 GMT -5
A compression / leakdown test would be a good indicator. Pressure from combustion can blow-by the rings and into the crankcase, pressurizing it.
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Post by usmcdoc on Nov 5, 2011 20:12:40 GMT -5
90GTVert...the odd part...if it is rings..it does not smoke or burn oil.....just blows it like a fountain from the vent tube...
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Post by 90GTVert on Nov 5, 2011 21:24:45 GMT -5
It is possible. Again, a leakdown / compression test would be good. If it were mine, I'd probably just tear it down and look everything over. Something's gotta be wrong in there to push that much oil out.
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Post by speedy1125 on Nov 5, 2011 21:32:00 GMT -5
Just outta curiosity....when all the oil blew out over 5 miles(and I was unaware of it until I stopped) If the rings wore....would that allow some sort of blow by into the head causing the oil to blow out the vent hole each time I fill it?...Power seems down as well. Valves are both set at .004 so I know that is ok. I think you have your problem right there. is the plug oily? then again one has to wonder why all the oil blew out in the first place. |
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Post by usmcdoc on Nov 5, 2011 21:51:30 GMT -5
Plug is clean.....non fouled.....light brown in color....
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Post by speedy1125 on Nov 6, 2011 2:27:55 GMT -5
one thing is for sure...time to take the motor apart.
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