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Post by kczukiman on Nov 10, 2011 23:14:52 GMT -5
I just put my second new BBK 70cc on my beamer.The first one Lasted about 200 miles befor the snap ring that holds the piston on came loose and gouged everything.On this new, I was very carful and gaped my piston rings @.008 as directed in the forum.After I installed the kit,I started the moter and it ran for about 5 seconds and then I heard a pop and it shut down.I pulled the cylinder back off and noticed that the bottom piston ring was jammed into the piston groove and scratched the cylinder just to the right of the exhaust port.I have a back up piston and rings . Any ideas what could have caused this? Is it possable to take 600 sand paper and smooth the cylinder and put the new piston in and it work?
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Post by 2strokd on Nov 11, 2011 1:42:30 GMT -5
Dang! Sorry to read this..
The only thing that sticks out in my head is a ring that wasnt lined up with the piston pin proper.?.. The lil pins for the rings.
That, or maybe a ring got or had a small crack on assembly and broke on start-up? Is the ring broke?
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Post by kczukiman on Nov 11, 2011 8:29:13 GMT -5
The ring didn't break. It did have a small section that is stuck in the piston groove by the piston pin. I did break the ring off trying to remove it from the piston.After I installed the head,I turned the flywheel with my and a few revolution just to make sure everything was smooth.The cylinder scratch is very slight,the side of the pistion took the brunt,by having a deep gouge. I do have a back up piston and rings ?
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Post by 90GTVert on Nov 11, 2011 10:58:38 GMT -5
Maybe something was wrong with the ring land on this one? When you install a new piston I would suggest looking it all over and being sure that the ring can move freely in the ring land. If the cylinder scratch is very minor it may not need attention. Just check to see if you can feel sharp edges there and if you can then you might wanna hit it with some fine paper just to remove anything it could snag on.
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Post by kczukiman on Nov 11, 2011 18:56:31 GMT -5
That sounds like a winner. It is very minor. I will go over it with some 600 paper. You know you may be right. I never check the ring land. Thanks !
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Post by kczukiman on Nov 11, 2011 20:23:13 GMT -5
I notice even with the piston out trying to geep the ring perfect is a rough to do. As I squeeze the ring it seems to one way or the other want to go over the the piston pin.
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Post by kczukiman on Nov 12, 2011 1:21:41 GMT -5
I have the new piston and rings in. It fired rite up but I couldnt leave it run very long the wife was asleep aboove me in the garage and it is 12:20 am. Tomorrow I will be the real test.
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Post by kczukiman on Nov 12, 2011 12:16:26 GMT -5
update: First test ride went well. Motor seems strong. Tried to stay at about 7200 rpm while from time to time leting of the throttle to let it coast .Scooter is cooling so I can check the plug. I also mixed extra oil into the gas for extra lube.
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Post by stepthrutuner on Nov 12, 2011 13:59:36 GMT -5
If we two stroke tuners had to wait til the engine cooled to check our burn we never woulda even got into 2ts. Is there some special reason you have to wait for your scooter to cool furrin you inspect the porcelain??
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Post by kczukiman on Nov 12, 2011 14:18:23 GMT -5
If we two stroke tuners had to wait til the engine cooled to check our burn we never woulda even got into 2ts. Is there some special reason you have to wait for your scooter to cool furrin you inspect the porcelain?? Not really, I had to wait until it cooled down completly to take it out for another run so I figured I would check the plug then. By the by as you well know, changing hot plugs isn't just limited to 2t's...  |
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Post by kczukiman on Nov 12, 2011 14:32:47 GMT -5
Second run went well, Spark plug still looks good. I do notice for some reason on this Kit, as opposed to the other, Its a lot more sensitive to the carb adjustments. Geesh good thing I added a tach.
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Post by stepthrutuner on Nov 12, 2011 14:44:17 GMT -5
Certainly. Good luck with this one. :thumb:
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