G2A - backfiring bad

[jscritch]

I just started this project cart. (G2) It was found in a field.
I had to rewire it (rats had got them), put a used starter on it, starter relay, and have put a temporary gas supply on it.

I got it started, but it is backfiring both ways.
Here is the link to youtube video of it running.

cart backfiring - YouTube

cart backfiring - YouTube

I tried 3 times setting the valves based on the service manual.
I tried adjusting out with carb, cleaned carb thoroughly as well.

Anybody got ideas?
Any help would be greatly appreciated!

[sho305]

I would run a spark tester on it, sounds like bad spark. They are cheap, $5 or so and you can see if you have a steady spark. A cheater way that sometimes works is pull the plug boot part way off the plug so it has to jump spark to the plug, that will make spark stronger if it works but may not. I should say most don't but I have seen them run that bad just because the airbox was off. They are strange that way and will foul the plug just for that reason alone. I rejetted mine and tossed the silencer off the airbox, no problem after that.

[1989Marathon]

Looks like fuel spitting out around one of the mounting bolts. Is that what I'm seeing?

[pachanga90]

I'm with Sho on the air box.Install that first and see how it runs.The carb is tuned for the air box and filter,and it will run a lot different if changes are made,and the carb isn't retuned for them.My wife's was popping with the filter removed(it was clogged,and I needed to run the cart that weekend,and the new filter hadn't been delivered yet),new filter,and it ran perfect again.

[jscritch]

Thanks guys!
That is not gas spitting out. It is a shiny carter key spinning and bouncing due to vibration.
I will try the airbox next then check back.

[smallblock450sl]

Might check the "small" black ground wire at the starter generator. Cut it off the main negative battery lead and used your own eye end to attatch it to the stud. It's the main ground for the wire harness and the ignition is based on "open/closed" ground. Also check the primary clutch for a broken weight. Good luck.