Atlas should piston top be above cylinder?

Atlas 750 engine in a Hybrid G15. The piston tops sit .055" above the cylinder at top dead center. Is this correct?

More familiar with Commandos which are flush.

Thanks

Mark

well you right they should be flush with the top of the cylinders at TDC. so something not as it should be,

It depends of course on what compression ratio pistons are fitted. From hazy memory (it's years since I took the head off my Atlas), the original dished pistons did not protrude above the cylinder but the replacement Commando pistons did. I would rather have usedlower compression dished pistons but they are no longer available. If your engine has been running in its current state, I wouldn't worry.

My Atlas has HC pistons fitted and they protrude. I don't know by how much and I am not taking the head off to find out!Gordon is right. If it was running OK, don't worry.

Anna, your comment is correct but, as is often the case, only when referring to the original specification. Many Nortons that are running today will not be to the original specification and are not necessarily the worse for that. Inexperienced Norton tinkerers easily can be disconcerted by differences from the description in a manual or parts list that are of no consequence.

With standard or commando pistons, if you have early barrels with a spigot the pistons do not protrude above the spigots. If you have later barrels or the spigot has been removed, then the pistons will sit slightly above the gasket face.

Paul