Crossed a set of rough R/R tracks into a grade when it first occurred then no problem with speed until the next hill. Same thing again so went to low gear and not a problem. As soon as a load in high gear boom it happens again.
I blew apart the outer layer of the muffler just before leaving but I wouldn't think the muffler would be the cause.
Any help is appreciated
Did the coils shake loose?
Something to look for. I'm out of the province now for the weekend but will look at that as soon as I get home on Monday.Hope it's a simple fix like loose coils.
I had a friend who kept having to take his wife's car to the dealer to have the ignition switch replaced. To make a long story short, his wife had a wad of keys with a flashlight and key fobs and a rabbit's foot that weighed about a pound. All that weight was pulling so hard on the key that the switch would sometimes turn itself off.
Unlikely that this is your problem - I would check for bad coil box wiring or loose connections in the ignition system generally.
Check the nut on the mag post and the connection of the mag post wire on the back of the switch. They can both work loose. When it does it again, switch to battery. If it still backfires, it may be a coil connection. If it resolves, it's in the mag wiring. Look for the mag wire grounding against something.
I had these symptoms one time. Blew apart my muffler. Couldn't find the problem. Turned out my rebuilt roller timer had a crushed washer at one of the contacts that caused a cylinder to fire randomly.
It took close inspection of the terminals to find the problem.
Only backfired at low rpms under load. Weird.
I forgot to mention....check ALL the connections at the terminal block on the firewall......been there and done that.......
Fuel starvation causes popping too, make sure your tank is full.
Not likely fuel starvation if you blew apart your muffler, more likely an ignition problem allowing unburned fuel into the exhaust, or too high a float setting, but I would look at the coils first,
Found and fixed it today."Thanks everyone" It was a crushed washer on the roller timer causing a ground.
Also replaced the outside skin on my muffler. The hardware store carries a 5 inch stove pipe which cut a foot long is identical and sounds great. Don't know how long it will last but appears to be almost the same thickness.I can always replace it with another one. The price is right.