426 Blue wire on carb

I was told that if I cut the blue wire on the carburetor it will start better and save on spark plugs. The factory put it on there for some reason, what problems will I cause if I cut it? I only woods ride and the gearing is way high so I kill it if the tire is not spinning around the tight places. Will 13/ 51 gears be low enough?

It is called a TPS (Throttle Position Sensor). It would be much better to just unplug it though I think somebody was telling you about the disconnecting the neutral switch. Disconnecting the TPS does change the curve for the better according to FFRacing (Tryce). Unplug it and judge for yourself. The neutral switch seemed to help mine start more consistently however I am always in search of better tune.

Fastest1 is right... The blue wire is not on the carb but on a plug by the right radiator. It is the light blue one. If you remove the wire, it is supposed to allow your bike to start easier. I have not personally done the mod "yet". But I have heard mixed reviews on it. Works for some and others can't tell the difference.

I took the pin out of the socket so that I could replace it to factory if it has problems. It now will start on the first kick, so we will see if it causes other problems.

I always thought mine did better after the disconnection of the neutral switch also. Couldnt tell you why but I havent changed a plug in years due to flooding/fouling. I keep meaning to do the TPS but never get around to it even though it couldnt be easier or more accessible. The other things I do to minimize any problems are, turn off the petcock and let it run for a minute or two every time I kill it and the BK/GB mod. BTW Tim Ferry's bike never had the TPS on it when he raced the 426 for Yamaha! Always made me wonder. FFRacing swears by it and they are flattrackers.

will that work on an 02

426

will that work on an 02

426

Yes it will

"have you turned in your TPS reports yet?" (Office Space)

ANYWAY...I disconnected the TPS on my 426 "back in the day" and did not like the way it ran...but it could have been all in my head. I hooked it back up and was a happy camper.

I did leave the nuetral switch disconnected and eventually took it and the wiring harness completely off the bike. I replaced it with one of the neato Dr D site glasses.

I've done the blue wire mod and couldn't tell any difference, so I hooked it back up.

So the Blue wire is the TPS, is the yellow wire the neutral switch? and what kid of damage can happen if i disconnect both?

No, the blue wire is the neutral switch. I don't know what the yellow wire is, but the TPS is the black piece on the left side of the carb, it has 2 or 3 wires coming out of it and they go to a connector that is tied to the down tube that goes toward the pegs. Just unplug it there and try it out. If you don't like it just plug it back in. Hope this helps.

Josh

Will 13/ 51 gears be low enough?

That's what I run in the woods, works great for me along with a 12oz FW weight. :applause:

what exactly is the job of the TPS and the neutral switch? I have the hardest time finding neutral on my 426f while it's running.

TPS aides the ignition module in mapping and changes the output mapping to suit the throttle position. Neutral switch is related to noise testing in Europe, it retards the ignition to a lower RPM in neutral where their sound testing is done. I removed the neutral switch and its wiring in 2003 and installed a Zip Ty cover. No problems what so ever.It does not effect the neutral sensitivity of the shifting at all. Adjust the clutch cable or check/replace the clutch plates for more positive shifting.

Bill

TPS aides the ignition module in mapping and changes the output mapping to suit the throttle position. Neutral switch is related to noise testing in Europe, it retards the ignition to a lower RPM in neutral where their sound testing is done. I removed the neutral switch and its wiring in 2003 and installed a Zip Ty cover. No problems what so ever.It does not effect the neutral sensitivity of the shifting at all. Adjust the clutch cable or check/replace the clutch plates for more positive shifting.

Bill

Correct the neutral cover is ok to remove and never cut the Blue Wire or any other wire for the TPS. If you feel the need to disconnect it - just unplug the coupler. I have tried this both ways and my bikes 426s/450s run better with the TPS plugged in.

I would remove or disconnect neither of them. The neutral switch has no effect on performance whatsoever, since it's only active in neutral. In neutral, it lowers the rev limit and sets an alternate ignition map in place. Some people with 426's have disconnected this and found that their particular bike starts better, which they incorrectly believe is because the unit produces more spark energy with the switch unhooked. It doesn't. It's all a matter of the individual bike liking the more advanced timing. I can tell you for certain that my '03 starts better in neutral, and it's not because of clutch drag.

The TPS, likewise has little direct effect on full throttle operation. It is used to enable the CDI to control the ignition timing based on engine load as well as on engine speed, just as a vacuum advance used to do on an automobile engine. When disconnected, the unit simply behaves as if the throttle is always at WOT, and part throttle performance can suffer. It can also alter the max ignition advance curve in some cases, depending on how the unit defaults without it, but it isn't necessarily a good thing.

TPS aides the ignition module in mapping and changes the output mapping to suit the throttle position. Neutral switch is related to noise testing in Europe, it retards the ignition to a lower RPM in neutral where their sound testing is done. I removed the neutral switch and its wiring in 2003 and installed a Zip Ty cover. No problems what so ever.It does not effect the neutral sensitivity of the shifting at all. Adjust the clutch cable or check/replace the clutch plates for more positive shifting.

Bill

thanks for the info man! :applause:

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