I have my carbs off in order to do some jet work. I decided to check the resistance across the Throttle position sensor since I am chasing poor performance below 5000 rpm.

As installed it read 465 ohms in the idle position.

With the sensor removed in my hand in the free state, it reads 490 ohms. I have tried to reassemble the sensor onto the carbs in the 490 ohm position only to discover there is no way to get the bolt holes to line up with out some serious grinding.

I think the sensor is shot, but I would rather not spend the $100 if I don't have too. Any thoughts?

A little history:

I recently had the bike Dyno Tuned. Apperantly the guy does not have alot of superhawk experience. He tuned it for the high end. Runs like crap below 5000. Come to find out he put a 190 front main jet, 192 rear main jet, and put the needles third from the top.

I am changing it to the Factory Pro recommendations of 180 front main jet, 182 rear main jet, and needles fourth from the top.

I had adjusted the sensor down from 800 ohms to 500 ohms several years ago. I had not checked is since.

Any input would be appreciated.

 

Punch out the brass ringlets from the mounting holes. That should give you enough lattitude.

 

+11

 

I looked at punching out the rings. It still won't give me enough room to set it right. That is why I think the sensor is shot.

 

It's only shot if resistance won't change with throttle position, or if it's erratic. The manual describes bending a tab *carefully* and then reinstalling it. I've not done this but others on the forum have.

 

Pop the spacers out and then elongate the holes in the plastic with a round file, so that the spacers slide in the longer holes. Then put the spacers back in. They will now move with the bolts, and still protect the plastic. You will then have the extra adjustment you need.

 

I don't know if the sensor resistance changes as the throttle spools up. I don't have that many hands.

I guess what I don't understand is that I had enough adjustment to adjust the sensor from the factory set resistance of 800 ohms down to the recommended 500 ohms several years ago. Now the resistance has dropped 25 ohms and I no longer have enough adjustment to bring it back into spec.

In addition, just before discovering the change in the TPS I was experiencing what I will call significant valve noise at idle. I suppose this could be caused by incorrect timing, which points to the TPS.

I am probably going to get a new TPS and try it. It just sucks it is $75 and if it isn't the problem, they probably won't take it back because it is electronic.

I will post results with the new TPS.

 

Some folks suggest setting it to like 440 ohms. As long as you're between there and 500 or so, you're fine. Don't spend the $75 unless the symptoms listed by Hawkrider show up. Fix the jetting before doing anything else, besides maybe cleaning the carbs while you're in there.