# Stihl MM55 Tiller Won't Start



## Switlik21 (Sep 25, 2021)

I picked up a cheap MM55 tiller from craigslist. I checked there was some compression before buying knowing at minimum I needed a coil since the spark plug wire was half missing

I got it home. Cleaned it up, replaced the ignition coil with an aftermarket from amazon and replaced the carb with a stihl genuine carb. Through sparkplug hole and exhaust hole i visually looked at cylinder and it looks pretty good. Also checked the exhaust for blockages. I have spark, I have fuel but I cannot get this thing to start. I prime the fuel, set the choke and pull and by 3rd pull I get a backfire that shoots exhaust and spark from both exhaust and intake. No matter how I have choke set I can only get a backfire after so many pulls. Will not start. I've tries setting the catb per factory too.

I pulled the clutch and flywheel and it doesn't look like the flywheel slipped but there is some play between flywheel and shaft due to key way. I set it by splitting the difference. Didnt seem to make a difference.

Any ideas? This one has me stumped. Feels like a timing issue but dont know what to check now.


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## cscltd (Oct 8, 2021)

Amazon coil is no good or someone Frankensteined it with wrong flywheel or big air leak


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