Motorcycle Repair: Desperate need for advice on an air cooled 2-stroke engine, attex atv, snowmobile type

Question
Hi Mitch,

We have an Attex ATV with the G50B Chapparral engine (484cc - Fuji Xenoah Corporation. The engine is a snowmobile type. For some time now, it has been rather un-reliable. The engine has been bench tested, new points, serviced and timed by a 2-stroke mechanic. Just the other day I had an issue with it flooding, not wanting to start. Took carby off and checked it over and put it back (didn't really do anything, so maybe the floats or needle was stuck?). It then started, but idle was really low and just wanted to die if I took my hand off the throttle. I ended up getting it to idle a bit better and took it for a run down the road. Poping was coming out of the carb and it was missing as well as laboring under load. I gave up and put it away... I had someone think it is a connection near the coil... I guess this makes sense when spark on one of the cylinders drops out at times... We plan to check connections and solder up any loose connections.

To give a bit more history to the reliability problems... In the past, we have had it act up after about 1/2 an hour of driving. When I say act up, it starts to "pop" (through the carburetor I believe) and the engine starts to lack power and when you give it more throttle, it can "pop" even more. I am pretty sure it is a "pop" through the carb as I also had it backfire through the exhaust only once and that was like a gun shot with a "bang". Once, the engine quit on me when I was out driving and I was not able to get it re-started for the next 15-20 minutes. It nearly seemed like it needed to cool down? We thought the electrics were getting too hot, so we ended up relocating the coils and condensers from the original place and placed them away from the engine. Our reason for this was we believed these items were getting way too hot in that little compartment. I haven't had the chance to really take it for a good long run to see if this has worked or not. We took it along a beach for a few miles where the sand was really soft and the engine really worked hard. On that occasion, it all worked fine.

I am desperate to get the vehicle running in a reliable state and thought I would drop you a line to get your opinion. We cover long distances and reliability is very important as you can imagine (ha, ha - nervous laugh)

Thanks,
Steve

Answer
change out the coils this is your problem no matter where they are placed, they still get hot due to the voltage they put out . the bike starts cuttn out once the coils warm up thats the problem. they are defective even if you test them they will show good but in reality they are not .
good luck hope i have been helpfull dont forget to rate my question thanks. keep riding