Gas engine backfire

[Red Raider]

I've never had this happen before, so I'm a little confused. I was starting my Syssa 30cc for the first run of the day. It backfired - sounded like a firecracker, not like the ususal trying to start sound. The energy was great enough to loosen the prop nut. Took the spinner off, reset the prop to the 2 o'clock position and tightened it back up. First flip, it did it again, this time hitting my hand. Blood flew, there was some colorful language, and a 10 minute pause in the action while I tended to a couple of very sore fingers.

I went ahead and kept working with it. I got it to start and it ran fine and didn't do it again. I'm wondering if I left fuel in it from the last time a flew it if that would cause it. Any ideas??

 

[Jlc]

I remember looking at buying this engine and some people were having this problem. I think it was a broke woodruf key. I'm sure I didn't spell that right. I would be hesitant to stick my fingers back in there until you get it looked at.

 

[Terryscustom]

I agree, I had the same thing happen with an EME120. Broken woodruff key allowed hub to spin and advanced the timing.

 

[BarracudaHockey]

A couple of things here, and I have no direct experience with that particular engine.

Backfires usually happen when giving a lazy flip, you have to flip with authority and follow through.

Timing problems (as noted) cause them.

Learning the technique of placing your fingers flat on the prop and flipping it that way will keep you from getting your fingers whacked

 

[bigblueswope]

Paint Roller, I'm a big baby so I always use a paint roller as a chicken stick.

These digits are the only thing that keep my family fed. Way too expensive to risk them on a hobby.

 

[Terryscustom]

Paint Roller, I'm a big baby so I always use a paint roller as a chicken stick.
These digits are the only thing that keep my family fed. Way too expensive to risk them on a hobby.

Good point on the flipping with authority and tuning. I'm exactly same as bigblueswope, I had a 32x10 Falcon give me a few stitches when I was talking to someone and flipped with my skirt on...........and have never flipped a prop with my fingers again.

 

[Red Raider]

Woodruff key?!?! I never would have thought of that. I had just changed the prop. I bet I let it fall out somehow and didn't notice it. I'll check that first thing when I get home.

 

[Red Raider]

I have a chicken stick that Todd Syssa gave me when I bought my 4th engine from him. I've never used it. Guess I may start.

I know what you mean about keeping your fingers flat against the front of the prop and not grabbing it. That's how I missed getting hit the first time. I've gotten so comfortable with gas engines that I just expect them to perform right first time, every time.

 

[Truckracer]

Yup if it is a Syssa, its probably a sheared key. I believe they had an update fix for that problem. Send it in, you should have it back in 6 months or so.

And yes, that last sentence was a snarky jab at Syssa!

 

[Red Raider]

I have heard the same thing. Customer service is the number one thing that kept them from becoming a true force in the 30cc engine market. I readily admit that there are far more stories about terrible service than there are good ones. BUT, my experience has been the absolute opposite. I bought one of the first engines they produced. It was terrible. Couldn't keep the muffler tight, the carb was a joke, and getting one to keep running was a continuous science project. I replaced the carb, installed a Bowman Ring, Todd upgraded the muffler design and all was well. Over the last several years I've bought 3 more. Dang good engine. The only time I ever had to send one back, he returned it before he even sent me an invoice for the repairs. It was gone from my house less than 10 days. Same is true for everything I've ordered from him. I use the Techaero IBEC from him, get props and other accessories. I've never had an issue. Guess I'm one of the lucky ones.