I'll try to keep it brief: I had a local Indy install a True-Track on the rear of my bike and now I have backfiring. (Yeah yeah, small task, but it was 110 degrees here the other day, got the bike on the lift and did not want to deal with it- motor mount bolts were torqued to a million ft lbs and it was way too tight back there). Indy knocked it out in less than an hour, super cheap. Worth my money.

Anyway...I'm trying to figure out the cause. There are way too many variables I'm trying to eliminate.

A) while the Indy was sizing things up he said "this wiring harness is going to be a bitch, it's right back there and it's going to get stuffed". Could something be pinched, or a ground wire loose? One of my bikes had backfiring when the battery cables were loose...essentially the bike was stalling and starting up again when they made contact and backfiring a lot. Similar issue?

B) as I was leaving the shop, Indy told me my brake light was stuck on. I thought he ****ed something up with the rear brake wires, but we determined it was the front lever switch. He didn't have an extra switch, so we ghetto-rigged some tape/cardboard in there to make contact with the switch. Would opening the switch housing or this tape/cardboard have any effect on the throttle positioning?

C) my clutch cable was a little loose and we snugged it up a bit....cause for backfiring?

D) I got a tank of gas about a block away. Maybe just bad gas?

E) it's been hot as hell here, can super high temperatures be affecting the carb or motor and fuse backfiring?

This is more than a little crackle, it's several very loud POPPOPPOPPOPPOPOPOPPOPs when I roll off from 4rpm through 1rpm.

I'm stumped. It's too big of a coincidence that everything ran perfect, now I suddenly have an exhaust leak or carb issues. But what could cause some
Kind of air/fuel ratio issue around the motor mount?

I really think maybe some kind of ground wire.

Let me know your thoughts, thanks!

 

My thoughts are that you have an exhaust leak and the air is getting in and re-lighting, causing the backfire on decel. Did he loosen any of the exhaust? If so, look there first .

 

Didn't touch the exhaust. I checked all exhaust brackets and head bolts and everything was good.

 

I addition to the wiring above the trans, you might want to check the crank and cam sensor connector under the crankcase. Maybe got pinched/stretched when he lifted the engine.

 

Backfiring through the exhaust is always intermittent ignition. Back firing is not to be confused with the decel popping you get with the throttle only at idle. That is caused by a lean idle mixture. Backfiring happens at any or all throttle settings, and means you are losing spark intermittently. It could be the plugs, plug wires, coils, coil primary wiring, or anything else that breaks the ignition circuit.

I am a firm believer in looking first where the last work was done. I'd pull the harness, looking over the connectors and insulation where the Indy was working. Then repack it properly.

 

I'll double check everything when I get home, but funny turn of events on the ride to work this morning. There's a long stretch of straight freeway where I usually hit 90-100mph just because. Approaching a light at the end of the freeway, the bike stammered and stuttered as it popped upon downshifting. The bike died at the light. I started it up and it made a loud pop.

The rest of the ride was great, no popping. Maybe some gunk was backed up and cleared out?

 

I'm going with cggorman and CJD197's assessment here; you've got an ignition issue, you've got no fire. If it ran great before the Indy got their hands on it and it won't run properly now, you've got to go back through the bike and find what is breaking the ignition; something is being pinched or pulled...

 

"While the Indy was sizing things up he said "this wiring harness is going to be a bitch, it's right back there and it's going to get stuffed". Could something be pinched, or a ground wire loose?"

When I fitted my Sputhe rear unit, the instructions mentioned that that harness needed to be shifted up and across in a specific way. They are similar to the TT unit but might differ in that area). I'd maybe start there...
.

 

Died twice on the way home and a bunch of crackling...gonna take a gander tonight

 

First TT I installed, I pinched the fuel overflow/vent line with the rear mount bracket. It caused all sorts of pressure to build up inside my tank. I can see where it'd be easy to pinch that harness back there.