How to Adjust the Throttle Position Sensor (TPS)

[VTRDark]

The TPS is very basic. All it does is tell the Ignition Control Module (ICM), where the map is stored, what your throttle position is. The TPS is mainly only effective at idle/low revs, steady state cruise.

Does the throttle sensor setting shift the entire advance curve?

I highly doubt it but cant say for sure as I have not taken a reading from the ICM. I'd love to be able to play around with the curve. As it stands, all one can do to shift the curve as a whole is fit an ignition advancer or retarder.

Ignition Timing Advance or Retard The Why's and How's

I have some problems starting which were indicative of overadvanced ignition.

What makes you think that I would start looking at other more likely causess for problems starting. Starter motor bolt corrosion maybe. It's one of the common faults!

but occasionally it gives the overadvanced struggle effect. What I have noticed since is rough running at around 3000rpm.

What's the carb setup with regards to jetting/mixture. You may need to tweak your fuel screws. Is the air filter standard and clean. Also have you done a carb sync/balance since adjusting the TPS. If not then do this first.

How to balance your carbs

Carb Tuning Guide

(:-})

[thunderbolt]

Yeh check and adjust it while the Carbs are off. The only reasoning for balancing first is because this alters the position of the throttle plate which is where the TPS takes it's baseline reading from. It wont make a huge difference not balancing first, not unless it's massively out to begin with.

(:-})

Thanks Carl,

I went out to the shed after reading your post on the TPS adjustment. Slapped the multimeter on the terminals and received a reading of 794Ω as below.



I then was able to reset it to approx. 500Ω without having to file out the slots in the TPS and without having to use the special tool to loosen the two screws holding it in place - replaced them with hex head screws.



It was quite a simple job really, I thought it would be a bit more involved than it was.

Learnt a lot through this exercise and the willing advice of others on this forum. I am ok at building motors and such, but each bike has it's own uniqueness and there is no-one better to help in these cases that those that already own and have worked on these bikes themselves. Thanks for sharing your experience with me.

[13yearsVTRrider]

Thanks Guys
After I reset the throtlle pot, I set the idle mixture using my Gunson Gas analyser, and finished up with 4% CO. This may be borderline and could cause the roughness. Otherwise, it has incredible mid-range torque. I'd be interested in other opinions on how the performance should be above 6500-7000rpm though.

[kev64]

Did mine today, bent the left leg a bit and set to 495ohms no problem
Went to halfrauds and made up spade connectors to get a good connection
On riding through my town seamed to pull OK above 2000rpm without being jerky etc,
Gonna give a bit more testing tomorrow, hopefully not affected my midrange!!
Also appears to get ride of the occassional cough !

PS, did this without taking the airbox off, just lifted the front of the tank

[Bikermort]

Tip for doing this quickly....No need to take carbys off. Leave harness connected to TPS. Remove connector from ecu located left rear under seat. Probe corresponding wires with multimeter there and adjust TPS. Takes about 5mins.

[VTR Phoenix]

When I did mine I just used little crocodile clips, lifted the tank and connected up and adjusted as required. Defo no need to remove carbs.

[msamson55]

Mine has shear bolts from the factory, I was wondering what size the bolts are so I can go to the hardware store and buy new ones before I drill them out. Currently my truck is in the shop so I can't drill them out and take them with me to the store because My VTR is my only ride currently

[popkat]

Mine has shear bolts from the factory, I was wondering what size the bolts are so I can go to the hardware store and buy new ones before I drill them out. Currently my truck is in the shop so I can't drill them out and take them with me to the store because My VTR is my only ride currently

They shouldn't be shear bolts, they should be security bolts, like a torx bolt with a pin in the middle, you need a security bit to undo them.

This set has them and it's cheap
https://www.ebay.co.uk/itm/100PC-CHROME ... t+set.TRS0



.

[msamson55]

IDK if its because its a US California bike but they are shear bolts

[msamson55]

Mine has shear bolts from the factory, I was wondering what size the bolts are so I can go to the hardware store and buy new ones before I drill them out. Currently my truck is in the shop so I can't drill them out and take them with me to the store because My VTR is my only ride currently

They shouldn't be shear bolts, they should be security bolts, like a torx bolt with a pin in the middle, you need a security bit to undo them.

This set has them and it's cheap
https://www.ebay.co.uk/itm/100PC-CHROME ... t+set.TRS0

thanks for the fast response by the way I've lost a lot of blood, sweat & money restoring the bike but its been worth it I've fallen in love with my VTR

.

[tony.mon]

They will be m5 or M6, so just get some spare of each and drill them out.

[msamson55]

They will be m5 or M6, so just get some spare of each and drill them out.

thanks so much your amazing

[AMCQ46]

in California they will tamper proof anything that could effect emissions, so that may be why you have shear bolts and the EU crew have tamper torx

[msamson55]

Yeah they really don't want you messing with it. It took me almost an hour to get them off it was set to 846 ohms and the lowest I could set it was 532 ohms.

if anyone else has this problem drill it down the center that way it will loosen itself when the head of the screw starts to bend up under the pressure then you can unscrew it by hand
The bolt size is M5 .80

[Rhughes945]

I do hate to dredge up old threads, but starting a new one is also as annoying.

I'm looking at doing the TPS mod to my bike, and just have a couple of questions.

Is it right that EU models don't have those annoying looking shear bolts? And I'd just need a torx bit to undo them?
No special faffery that might get me in trouble later?

I got a pair of m5x8 bolts from stores at work just to be on the safe side.