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.
rebuilding a honda gx31 engine on fg100 tiller
- Thread starter hmr123
- Start date
robert@honda
Lawn Addict
- Joined
- Nov 2, 2011
- Threads
- 97
- Messages
- 1,791
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.