How do you break in a new top end?
Break-In – When running your new top end for the first time, keep the engine slightly above idle, with slow and mild revs until the engine starts to get too hot to touch. Then, shut the engine off and let it cool until it is warm to the touch.
How do you know if you need a top end rebuild?
When you see dirt in the intake, you’ll need to tear down the top end to check for damage. A damaged cylinder may need reconditioning or replating. The same goes for when you find your intake boot and airbox was not sealed properly. Anytime you find leaks, you’ll want to tear down and inspect for damage.
Should I Change my piston rings or do an engine rebuild?
New rings on old pistons in a worn cylinder, bad bad idea. Then of course to replace the rings you need to remove the cylinder head and while it is off you will need to have it overhauled; valve guides, valves re-seated, cam bushes and seals etc. This means to replace the rings you are halfway there to rebuild the engine so rather do that.
When to use the top or bottom of a piston ring?
If the bore has taper the end gap will be; larger at the top and smaller at the bottom. Use the bottom position to set the end gap. If you use the top of a worn bore to set the end gap; the end gap will be too small, when the piston reaches the bottom of the bore.
When to reuse pistons or order new ones?
If either the piston or the top ring exhibit evidence of micro-welding, the only solution is a new set of pistons and rings. Avoiding a re-occurrence of this issue involves careful initial ring break-in that allows establishing early wear patterns that remove the tallest peaks early before maximum cylinder pressure is applied.
When do you Know Your piston rings are worn out?
A top or second ring that exhibits full face contact should be considered worn out. Proper ring performance and sealing is based on the rings sliding across a coating of oil between the ring and the cylinder wall in much the same fashion as a crankshaft journal rides on a thin film of oil between it and the bearing.