How To Rebuild Pitbike Top End

[@Nickfulcrium]

I’m having this issue where my new piston header gets really tight on the way down when it’s the exact same one do you the screws that mount the head are just bent

[@ronnir8138]

Helpful stuff

[@JarredLD]

cheers mate

[@high_lyfe8546]

I'm rebuilding top end on my 140cc, I have a new head to go on.
Do I set the piston to tdc then install the head and set marking for timing.
Do I need to set valves once this is done, and does it matter if I set timing with out compression stroke

[@JarredLD]

Once your bore is on try and leave the piston at tdc but if not dont worry just use the marking on the crank to get tdc( or sometimes 'f' for firing) depending what magneto you have. Then with the head make sure your valves are on compression stroke, you should be able to feel some roll back on the cam. line your markings up and put the chain on. Turn the motor over 2 times and the marking should be in the same spot you put them on, if not it is not timed correctly.

[@high_lyfe8546]

Sweet as I think iv done it right, I set the piston to TDC and marking on the flywheel on the T and sprocket on the mark.
Turned the flywheel twice both valves were closed after that with alot of compression.

[@high_lyfe8546]

Aww and the lobes on the rockers need to be facing the piston when timing is set ?

[@weesmokeythe2strokey352]

Just tap it in..