Long time lurker first time poster, great site! Question is recently acquired a good looking 260 pro, saw ran ok but compression around 100 with some sort of aftermarket top end. Decided to put new meteor complete top end on. Cleaned up intake and exhaust port without touching bevels on inside of cylinder, used oem .5mm base gasket,opened up exhaust, coated piston,rings and cylinder in a thin film of oil, and saw runs great with 175# compression after first tank of fuel. Question is.. I removed muffler cover to inspect cylinder and seeing a couple fine vertical scratches (2 on exhaust side of piston) didn’t run wide open out of the cut, just short revs to maybe 3/4 throttle, even added maybe a teaspoon of 2 stroke oil to tank. So is this normal? Do all cylinders/pistons get some wear?? Btw running 100ll/yamalube 40:1 and saw passed vac test. Sorry to be so long winded and thanks for any info
Meteor 260 cylinder
- Thread starter whiplash1
- Start date
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may have been debree out of the muffler
Yes, or something (dirt/crud) that fell into bottom end when doing the work.
Clean is good, and stuff a paper towel in around the connecting rod until you have the cylinder on.
Did you degrease and scrub / clean the new piston and cylinder?
Every new cylinder should have the port bevels gone over with a piece of machine grade sand paper, 320 grit or finer, especially AM cylinders. Just to make certain all sharp edges have been removed from factory machining, I have found some that did have sharp bits that would scratch pistons. Found a round ball of plating in one that actually was digging into a piston causing a very deep scratch/gouge to the piston and rings.
Didn’t degrease anything but did blow everything off after grinding and wiped clean with a gas soaked rag then dry one, all bevels felt smooth to the touch?? After 5 tanks today rechecked and scratches didn’t get any worse and noticed same faint vertical scratches on intake side of cylinder, compression staying about the same 175-180, guess I’ll keep going and check in another 5-10 tanks. Thanks for all the replies
