i have 2 of these tillers with identical engines both with the same problem. being tillers and run in dirty and dusty conditions and with a lousy air filter setup, it is no wonder i have some engine wear even with very low hours of operation. anyhow i have done many v-8s and motorcycles but i think these small engines are less forgiving. upon teardown both units had some minimal scuffing and scoring of cylinder walls and pistons. i do not have the correct bore gauges, mikes,dial indicators, etc. to properly measure all my sleeve ids,bores, clearances, etc. my question though to all you experienced mechanics though is i did a thorough clean-up with 400 grit but did not replace any rings,pistons,valves. what i did has worked countless times on bigger engines. my question is is it worth it just to at least try a set of rings not knowing how much they are? typically on these hondas is it more valve related? are they even worth trying to repair without all the necessary tools? i didnt hone the cylinder- was that a bad mistake? although i did clean it up where there are no visble score marks. right now both motors start up first pull but i have tremendous blowby with even oil coming out the breather tube. i have the service manual and when i see the tolerable service limits maybe these motors are just very sensitive to intolerances. thanks for any advice.
Probably the biggest obstacle on these small engines is, even as nice as they are, they are still 100% aluminum and do NOT have a cast-iron sleeve like most other engines. This means it's a real challenge to rebuild one and get it right. The cylinder walls, piston and rings are all special=-treated with some really high-tech coatings to get around the obvious problems with wear. Now Honda has been offering these engines since the late 90s, and the newest version of the little Honda mini-tiller has a even a slightly smaller engine (25cc) but same primary design; no cast-iron sleeve. Ever other engine Honda makes has a sleeve, except the GX25, GX35, and the older GX31 and GX22.
