I have been fiddling with my JD gt 275 for the last year or so,restoring it. Its been a project of...a little here and a little there as I've got a lot on my plate. I finally got to the point of being able to start her up...except it wasnt starting. I thought a minute, and realized the gas was over a year old. So...seeing as how I just couldnt wait , I decided to squirt a little fresh gas into the carb. It spun a few times....and then POW! and then flames out of the carb....arrrggh.....RUN!.....then RUN back ....then RUN some more. Dangit...where is something to put this out? oh...here come the wife with a wet towel. So I grab that and throw it over the carb. whew...thank god my wife was giving the puppy dog a bath! So...I survey the damage. Nothing bad at first, the filter is toast, alittle melting of the filter housing. But then I see it....the muffler is blown and separated at the seams! Dang...? I then realize the compression seemed to be gone some too. Uh-oh.....I'm thinking it may have got the piston. Dang-it....dang-it...foot! This is a low hour Kawasaki 17hp engine, with maybe 250 hours on it. All because I was too lazy to drain the old gas out. I'll start the disassembly later this week. I've got to get my taxes done......dang it
You think it took out the piston? Wow, that would be a huge amount of fuel. Have you checked the valves? I would think a valve could get damaged before a piston let loose? Particularly the exhaust valve since you got fuel all the way to the muffler.
My first WAG was piston . I guess I assumed the worst.Hopefully it will be something minor ...but I did spin it a good bit before squirting fresh gas into it. This mower has been notorious for taking awhile to start. It really needs a primer bulb like found on boats. I'll pop the valve cover off this evening and post back.