In an attempt to get rid of my backfire on decel without yanking the carbs, I performed the tps mod. Went well. Got it to 488 ohms resistance in idle position. One of the posts on the how to thread said it should read about 2000 ohms wot. Well I checked mine, it went smoothly from 488 to about 3500 at 3/4 throttle, the dropped down and fluctuate in the 300s the rest of the way to wot. No change in performance after the mod. Still have the backfires. Is this a non issue, or should I swap out the tps? Thanks in advance

 

It's a non-issue, have you removed the pair system? Aftermarket cans?

 

welcome aboard brooks. That may have been me that came up with the 2000 ohms. What happened is that because I didn't know how to read the meter I had, i gave up and tried to adjust by feel. So I turned the TPS until I could feel the spring engage thinking that maybe the spring had weakened. Later when I was helping a friend do some work on his bike, he said he thought he read that I was turning it in the opp direction, so we looked it up and found he was correct. I had turned it in the opp direction. By now i had a meter I could read and mine measured 2000 ohms and so I adjusted his correctly and then did mine. The funny thing is i could detect no diff in running over the 2yrs that it was wrong and turned in the opp direction from when I finally changed it to 500.

I don't believe you need to change out your TPS. The SH is notorious for back fire if everything isn't just right. When I first got my homemade carb sync tool working and didn't know how to control it, we messed up the carb sync a little on the same bike I had done the TPS. The owner, Steve, was freaked out thinking I ruined his engine as it was backfiring madly, however when we finally got the carb sync right, it smoothed out to perfect.

That said, it seems that anything out of wack make these bikes backfire and by this i mean that if something changes it can go from smooth to a clunking back firing maniac machine. Filter box mods, wrong filter, tps, carb sync, altered exhaust/carbs valves out of adj., loose ccts, and who knows what else all seem to result in some degree of backfiring, clunking, and any manner of strange and terrifying noises.

So set it to 475-500, sync the carbs and see what happens. I would adjust the valves and make sure you do the cct mod and adjust correctly.

 

Backfiring is a fuel mixture issue, tps deals with ignition.

 

Yeah... actually the post that explained why you bike still ran okay with the tps at 2000 is the one that said 2000 is wot. I am going to attempt the Carb sync next. Sounds like a easy procedure to screw up first time around!!

 

Just trying to eliminate all possible "simple" fixes. Other posters have said this had fixed their backfire issue so I thought I'd try.

 

I did remove the pair. Reeds were flipped by previous owner but lines were not removed or capped. Two brothers slip ons. 13000 miles. 98. Changed all fluids and plugs. Plugs looked good but rear cylinder plug had a little gas on it. I'm thinking on trying a sync, then a Carb cleaning if that doesn't work. The bike has plenty of power but the backfire is just not tolerable. I can't bring myself to engine brake because of it.

 

How did you go with this????