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Post by sjef on Feb 15, 2007 16:42:40 GMT -5
Hallo Hopwheels
did not know you had a new carb, i guess it is clean ;D
if you know the clearences you can decide what to do
e.g. maybe you must make some more room in the valve pockets if there is to little clearance.there is no need to throw the piston away.you also can throw in another gasket this will lowwer your compression ratioand give you some clearence.
regards sjef
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Post by hopwheels on Feb 15, 2007 17:02:46 GMT -5
I have several copper head gaskets. Cool. Thanks sjef. Getting frustrating! But, is the general concensus then that this is piston slap from incorrect clearance?
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Post by colinjay on Feb 15, 2007 22:51:50 GMT -5
HI Hopwheels,
If really get stuck and have to strip the top end, checking valve - piston clearance is not difficult. If you put strips of plasticin (play dough) about 1 to 2mm thick on top of the piston in the valve pockets, refit the head, cam etc, you then have to turn the engine over at least two times the remove the hard and check how much the plastcin (play dough) has been squashed. From my memory I think I once read that 0.5mm is all that is required, but from memory when I modified the piston in my hot motor I went to 1mm clearance to be sure I never bent any more valves.
You can check the squish clearance in the same way.
If you have to increase the clearance, machining the valve pockets deeper is best. If you go down the 2 gasket method, it is better to use 2 cylinder base gaskets than 2 head gaskets, as if there is a leak between the gaskets, all you get is an oil leak not a total loss of compression and a walk home. Been there done that!
CJ
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Post by Retread on Feb 16, 2007 15:36:29 GMT -5
If it were valve interference you would have a bent valve as soon as it started and lots of superhot combustion gasses comming out the bent valve. Likely it is not a bent valve. How about the valve clearances set at top dead center on the exhaust stroke instead of the compression stroke. This simple mistake can cause the symtoms you describe and normaly does not cause damage because the valves are barely opening and you have not driven it with the rockers flapping away in there.
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Post by Cameron on Feb 16, 2007 16:19:19 GMT -5
I can't help with the technical stuff, but I feel your pain. We've had ice over roads for the last 4 months and it finally melted almost overnight. So 10 hours of late night re-assembly and I finally got to take her out. In retrospect, riding with no battery, no turn signals, no mirrors, no fenders, no brakelight, and a racing exhaust that was hose clamped on because the bracket wasn't done probably wasn't the smartest idea...But d**n it felt good!
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Post by hopwheels on Feb 16, 2007 16:41:18 GMT -5
I'lll check that out. Then I'm going to try some VP110 fuel I have on hand. Checking a few more little things before yanking the motor again would be worth it.
Thanks again for all your support guys!
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