Hey Frets, I'll give you my two cents and yes, I've rebuilt a few engines too. My first two cycle rebuild was a West Bend engine on an old go cart. My dad was looking over my shoulder the first few times and he was BIG on new rings in a two cycle and "cross hatch" cylinder honeing with an electriic drill, a bucket of kerosene and a cylinder hone. I made sure I had no crankcase leaks and fresh piston rings. I used to race my friends who had the same engine and go carts and could always blow them away. Their dad thought that my father was performing some sort of voodo on my engine because my dad was a wrench of great renown locally. Later in life I had a Kawasaki 500 H1 triple and rebuilt it a-lot with the ol' ring and hone technique. What I didn't realize was that there were different grit stones available for cylinder hones and performed so many "ring jobs" that I prematurely wore out my cylinders. I later learned about the magic of molybednum coated rings and their rapid break in capabilities and that you NEVER HONED A CYLINDER WITH ANYTHING COARSER THAN A 600 GRIT STONE that was being prepared for moly rings. So I learned. I recently bought a used Enya .19 with the piston rusted fast to the steel liner and the liner subsequently rusted to an interference fit in the aluminum crankcase. A fair amount of propane gas heat and some judicious tapping on the piston crown with a hardwood dowel freed everything up. I cleaned up the piston and cylinder liner with a very gentle wire wheel in my Dremel rotary tool. Then I carefully "honed" the cylinder with a slotted wooden dowel and some 600 grit wet/dry paper lubricated with G96 gun oil (sort of a WD40 to the power of two). I did NOT want to see bare shiney metal in the cylinder, I wanted Smoooooth and polished. I spent very little time in that cylinder with the 600 grit paper. I have now this .19 and another that never suffered any indignities. The really sick little .19 has superior compression. I will never touch a ringless engine with anything more abrasive than a paper towel. If the piston/cylinder fit fails I will replace both at the same time. On a ringed engine I will go no further than 600 grit paper and attempt a nice "cross hatch" pattern in the bore - and hone for a VERY short period of time.

As far as your Saito goes you could have a broken ring. The circlip retainer on the wrist pin may have come out of it's seat and allowed for scoreing of the cylinder wall. If your Saito is a low hour engine I wouldn't be concerned about a taper worn in the cylinder. Possibly a brake cylinder hone would fit your cylinder but I wouldn't think of it. Hone it too much and you better have a source for oversized pistons. You can measure the cylinder with a bore gage and micrometer or a dial vernier caliper but a low hour engine shouldn't have a worn out cylinder. I would tear it down for inspection and if your wrist pin retainer failed and scored the cylinder buy a new piston and cylinder. On your tear-down put the same piston on the same rod and the assembly back into the same cylinder bore. Should you remove the circlips, wrist pin and piston reassemble with new circlips. Make sure the open end of the circlip is in either the 12 oclock or 6 oclock postition. Better yet, try to locate some teflon wrist pin retainers and lose the circlips. I would be curious if Frank Bowman could fabricate some brass or aluminum wrist pin retainers. I'm going to ask him. Heck, if he can fabricate piston rings my little ask would be a snap.

Anyway, listen to the plethora of responses I hope you get from the fine guys here who collectively present us with hundreds of years of experience. My two most memorable questions regarding control line leadouts and now ring end gaps have produced volumes of responses and books full of knowledge. I vote we change the name of this website from RC Universe to RC University.

Regards,
Bill