Timing Issue

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chamjisky

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hi
i have a 107cc bike .. i have issue with its timing..
the issue is that at TDC the T mark on flywheel doesnt matches with the notch in the crank case .. it always springs back a bit at TDC ..

here is a pic which i took from this forum and added my points..

my current settings are as outlined in red ..
i cannot make the fly wheel stay with the T mark alligned .. it pulls back .. i mean rotates back to the point highlighted in the pic.
what should i do ?
 

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welcome mate, have you tried removing your spark plug and then putting the flywheel T in line with the mark, dont forget it is on compression stroke so it is quite normal for the flywheel to spring back to the F or the opposite direction like you highlighted in the pic, as long as you hold the flywheel T on the notch on the casing and the timing mark on the cam sprocket sits in line with the notch on the casing there also your timing is spot on mate.
 
hmm . i did not removed the spark plug it was there..
so next time i will check it and verify it .. thanks
 
its completely normal for it to spring back like that mate. When you turn the flywheel your actually pushing the piston up the cylinder and are compressing the air. When at tdc the air is the most compressed and will want to escape so it will try and push the piston back down hence rotating the flywheel back a little until the air in the cylinder has somewhere to go or has enough space so that the air is not compress enough to not move the piston down any further. Which by removing the spark plug the air has somewhere to go and the piston will not be pushed down.
 

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