Will try again with the first poster cylinder and piston. Assuming rings are made for a 4.000 bore. We have agreed cylinder, piston and ring grow outward when at running temperature.

What I am asking is why do you need .020 gap? However, to get say .0065 ring gap would require a manufacturer to produce them like the guy in my video above or cut his finish product ring gap on a wire EDM.

 

You need gap because the ring grows, I thought we covered that.

 

Why does it have to be some gap? I would suspect that you want a gap that is sufficient enough to prevent butting which could cause the ring to break but not so much that there is excessive gas leakage..

 

Total seal, the outfit in the YouTube video says since pistons, rings and cylinders are all expanding at different rates, the ring gaps are listed that way.

 

So I just got off the phone with Fuel Moto and was told that they set the gaps to .024"/.032" because of the type of material used to make the cylinder Liner.. Was also told they've been offering this 110" combo for 10 years without issue.. Heat cycling is a little different from the way I've done in the past... I was told to make sure I get a fan on the base of the cylinders to cool the cylinder a little quicker.. It's because if any of the pistons stop at BDC (when shut off) the retained heat in the cylinder could cause the liner to clamp down on the rings tighter than necessary locking down the piston... Once broken in this will not be an issue.. It apparently only occurs during the first few heat cycles.. I'll be starting the motor tonight..

 

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I heat cycled mine with a fan. 10 seconds first. Then 20, 30. 1 minute.