Rebuild a Honda GX120?

Old 10-16-10, 08:51 AM
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Rebuild a Honda GX120?

I have a Honda GX120 on a Bluebird aerator that I do not know the history on. It did seem to run fine when we first got it, but it has since sat for a couple years and now will not start. Carb rot I assume. So, I'm planning to clean it up and address the carb so it will be ready for spring and wondering how far I should go.

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As I said, I don't really know the history. It was purchased from a HD Rental that was closing. It had a broken stop switch. Rather than fix it, they parked it. I took a chance and bought it CHEAP ($150). Replaced the switch and it started right up. I can't find any leaks although there was quite a bit of oily grime under the tank and behind the fly wheel. Could just be from gas spilling. There does seem to be quite a lot of carbon build up in the exhaust port, but I don't know what's normal. Compression is 70PSI, but I've read that it's not really accurate given a pressure relief valve/system in these engines.

I know most of you would say, "Who is this dumb*!? Don't fix what ain't broke. I know, I know. However, I'm interested in the project for fun and to learn. But, I don't want to rebuild it if it isn't close to needing it. I am mechanically inclined and tools are not an issue. I just don't have much experience with small engines.

Old 10-16-10, 09:57 AM
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I'd start with a splash of gas in the carb and see if it fires. If it does then go ahead and address the carb with a good cleaning and kit, and see if it still runs. If it ran when it was shutdown, then the carb is likely in need of attention after couple years of downtime.

Likely will be all it needs. 70PSI is still a bit low IMO, and I don't know this engine but I think it should be better. Could be a few things but likely just sitting and not having been warmed up in a spell. It wouldn't hurt anything to put a squirt of engine oil down the spark plug hole and spin the engine a few times before trying to run it. Compression after should be higher as well.

If it won't fire on a splash of gas and run on a carb overhaul, then surely we can advise you further.

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