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Post by bobby17772 on Jul 27, 2013 22:34:02 GMT -5
hey guys, I have a weird problem, my scooter has no compression. I rode it a lot of the day today and it rode fine, no loss of power, no smoking, nothing! And when I go to move it it starts and idles for a second and shuts off. I try to start it again and it starts spinning ridiculously fast (I even pushed the kick start by hand and there was like no force behind it.
this top end has like 625 miles on it and never gave me a problem besides running rich. (50mm bbk, a9 cam, uni filter, hot coil, big carb...23mm I think?) I have the needle set to as lean as it can go, I had it 1 above it for the longest time and it was still running really rich so today I moved it down to the last setting and it died...do you think that it ran way to lean? I didn't have a chance to pull it apart yet, but I've had a lot of small engine and normally when the rings go it at least smokes or something.
any help would be great
thanks
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Post by scootnwinn on Jul 27, 2013 22:37:38 GMT -5
And your valves were in tolerance when you checked them?
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Post by skuttadawg on Jul 27, 2013 22:43:58 GMT -5
Remove the sparkplug and check its color with this chart www.4secondsflat.com/plug_chart.html I had a piston crack and was an instant power loss but still ran . My dealer removed the hose from top of the valve cover to see if it smoked and it did which he said was bad . I blew it up again 6 weeks later but this time th piston exploded . Mad a (censored ) no way did I want another kit so I bought an Air Sal 50mm BBK . The timing chain may have jumped too . Does it backfire or sputter ? |
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Post by millsc on Jul 27, 2013 22:47:51 GMT -5
if it had no or too low compression it would not start at all
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Post by bobby17772 on Jul 28, 2013 7:00:03 GMT -5
they were a little off but when I put the cam in a few days ago I put it back. but what's stumping me is why would it run fine then die after a cold start (parked for 5 hours)
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Post by sickopsycho on Jul 28, 2013 7:20:25 GMT -5
Don't think you have much choice other than to break it down. Do you have a compression tester? Give that a whirl if so- but from the sound of it it seems as though you have either a stuck/toasted piston ring(s) or a shot/obstructed valve. One thing you might try is removing the valve cover and setting the piston to ***bottom dead center*** You can verify by inserting a straw into the cylinder where the spark plug should go and rotating until it wont go down anymore. Next take a rubber dead blow mallet and gently tap the valve stems down to effectively open the valves. If there is a carbon deposit or something similar stuck in the valve seat it will probably knock it loose. You may also be able to tell by excessive play in the valve clearance with the piston at *top* dead center but you might need a feeler gauge to check this. Just throwing out some ideas...
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Post by rockynv on Jul 28, 2013 7:49:54 GMT -5
How does the oil look? You could have a valve that has started sticking. Running too lean for a day could have put a number of pinholes in the piston or warped a valve.
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Post by bobby17772 on Jul 28, 2013 8:09:34 GMT -5
I think it may be my rings, I just tore it apart and and the piston is fine...black but fine. the spark plug is a cross between 7 and 3 but I think it's because it use to be so rich the plug would be wet after riding. I just can't believe without warning it just died.
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Post by bobby17772 on Jul 28, 2013 21:50:40 GMT -5
hey problem is solved!! I took the head off again because things just weren't adding up, I noticed that something brass (unconfirmed) was stuck under the intake valve not allowing it to close all the way. I took it out, put everything back together and it started right up. now my only question is...where did this come from and how did it get there. what in the valve train is gold/brass??
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Post by buford1488 on Jul 29, 2013 5:33:18 GMT -5
since i do these heads ever day the only thing in the head that is brass is the valve guide's.
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Post by scootnwinn on Jul 29, 2013 11:09:25 GMT -5
And now you are running with out one put it back in far enough that it allows the valve to seat properly
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