Re: Jetting needed with change of engine oil? (2 stroke)

Alan Jackson /
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that's a good read but ive always wondered why Kawasaki recommend such large piston to bore clearances.

also their "break in" treatment flies in the face of bedding in the rings and there is no wonder the pictures of the pistons show blow back.

every one thinks differently but to bed rings in I get the engine warm and then give it as much loads it will take but for 1 mile journeys so the engine cannot get too warm and seize. I was also told letting the engine overrun is brilliant for bedding the rings in ie rev it in first to high revs then shut throttle and let engine braking work on the rings

microscopically a new bore has lots of tiny peaks and troughs.

force the rings to lop off or truncate these peaks by forcing them outwards ie only way to do that is under lots of load, also use a crap oil.

if you use synth or a good oil the rings will just glide over these peaks and not bed in.

and what you get is the rings basically moving over lots of thin peaks. instead of larger surface area truncated peaks. less compression, worse sealing more blowback etc.

I used to baby my bikes during run in,. no load etc and then I wondered why I had tea stained bores after a hundred miles.

I now do it the 50 mile lots of load but only for very very short spells and have no blow back whatsoever and lots of performance.

I bore my 64mm bore ish Yamaha to 0.03mm.

that article says new tight rings can snap if overheated. I thought that's what ensuring enough ring gap prevented?

I always check my ring gaps on new motors.

all good fun

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