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Post by sickopsycho on Sept 29, 2014 11:33:04 GMT -5
So I was riding down the road, at full speed, and a belt broke. I replaced the belt on the side of the road and when i cranked the motor back up it sounded like garbage. No power, sputtering, wouldnt take full throttle. Had to ride home at a top speed of 10mph. Im looking at it and I think the timing might have jumped a tooth when the belt broke. The bike is running poorly. It will start and idle, but the carb is spitting fuel vapor out of the intake and it still wont take much throttle. Does this sound like a likely scenario? I have a performance (no rev limit) cdi so it probably wound up pretty high before i let off the gas when I was riding at full speed and the belt broke. And the problem only started after that. Anything else to check before I tear into the timing chain?
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Post by sickopsycho on Sept 29, 2014 11:46:34 GMT -5
Sorry- 50cc scoot (actually 72cc ;-) 139qmb engine. Anymore info needed and i'll throw it in here.
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Post by alleyoop on Sept 29, 2014 12:08:08 GMT -5
Easy enough to check, take the valve cover off, crank it over by hand and align the cam sprocket like in the following picture and then check the flywheel and see where the timing is at. If you don't know where the timing should be take a picture of the flywheel and case pointer WHEN you have the Cam Sprocket aligned at TDC. Alleyoop  |
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Post by sickopsycho on Sept 29, 2014 12:16:50 GMT -5
Yeah. That wasn't it. When I took the valve cover off I set the crank to TDC and the cam matched time. So, I went to check the valves to see if they were too tight or what and low and behold... the damn adjustment screw on the exhaust valve was MISSING!   So, there is a screw and a nut floating around my crankcase somewhere. I dumped the oil, found nothing intact. Bear in mind this engine has run for about half an hour since it got gone and any severe damage that is going to be done is probably done. What are the chances that this thing just got pulverized into shavings and came out with the oil? slim to none, probably. Crap. Well, short of tearing apart the entire engine looking for it I think I'm just gonna replace the offending rocker and roll with it. Any suggestions? |
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Post by alleyoop on Sept 29, 2014 12:20:02 GMT -5
Those are HARD metal parts your in big DO DO if you cannot get them out. Get a long handled magnet and see if you can fish them out if not start looking for a motor.
Alleyoop
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Freshman Rider
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Post by sickopsycho on Sept 29, 2014 12:53:08 GMT -5
That wasnt what I wanted to hear. LIE TO ME!!! =)
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Post by ramblinman on Sept 29, 2014 15:38:17 GMT -5
That wasnt what I wanted to hear. LIE TO ME!!! =) i went through this when i bought a used scoot. mine had the screw but no locking nut... with the valve cover off use a flashlight and look down the shaft by the chain. if you can see it you can get it out with a small magnet on a long pole. |
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Post by alleyoop on Sept 29, 2014 15:47:03 GMT -5
Not to worry everything will be alright AS LONG AS YOU DON'T START THE MOTOR  |
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..BAD TO THE BONE..