Piston Lapping
Just to clear out questions about lapping process.
Lapping process is hand done procedure, when some size will be set to desired amount. I have no idea why all manufacturers are making engines that tight, but defenetly with CNC machines it ca be done, so racers don't have to run in engines forever.
We used lapping procedure everywhere, specialy on custom made work.
Lapping piston tool is pretty much simple hand held device, look like bushing with bore diameter as piston diameter. It has cut on one side and tightening screw-so by tightening screw we can change internal dianeter. Simply can tell you, if anybody has MTX3 optional wheel hubs ( hexsogen outside)-so it looks similar. I still don't have digital camera, but ones I get one- I will put pics of it.
I use for final step lapping compaund grit 1800 mfg by Clover.
Please if somebody decided to try, first try on old piston-procedure looks pretty easy, but in the mean time very dangerouse-very easy overlap.
As a tip can give you my numbers for Novas based engines-dry piston stick to dry sleeve with little pressure and ones it stop mesure distance from the top of the sleeve to top of piston and I do 2.8-2.9 mm.