RPM fluctuation and surging

motolink

Nitrous
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Joined
Sep 11, 2010
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1,421
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Brisbane South, Australia
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2011 Roadster and 2001 Bonneville
An update, I checked the TPS a voltage it was .60v & ISC was .70v. The specifications for John’s tune which I have is TPS .64v and ISC .76v. So I replaced the TPS , set voltage at .64v, the ISV was only .72v, adjusted the stepper motor to .76v. What I did find was the adjusting nut on the stepper motor was very easy almost to easy to turn.
I started the motor and ran it until it was at operating temperature, the idle was good.
Rechecked the TPS & ISC voltage still at .64 & .76.
Haven’t been able to echeck the .5mm gap between the stepper motor and the throttle, having trouble getting access because the cruise control cable junction box is in front of the stepper motor. I will see what I can do tomorrow.
To much rain to be able to road test.
 

bebsy

Finicky
Joined
Mar 18, 2017
Messages
211
Location
Pattya Thailand
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2006 Triumph R3
An update, I checked the TPS a voltage it was .60v & ISC was .70v. The specifications for John’s tune which I have is TPS .64v and ISC .76v. So I replaced the TPS , set voltage at .64v, the ISV was only .72v, adjusted the stepper motor to .76v. What I did find was the adjusting nut on the stepper motor was very easy almost to easy to turn.
I started the motor and ran it until it was at operating temperature, the idle was good.
Rechecked the TPS & ISC voltage still at .64 & .76.
Haven’t been able to echeck the .5mm gap between the stepper motor and the throttle, having trouble getting access because the cruise control cable junction box is in front of the stepper motor. I will see what I can do tomorrow.
To much rain to be able to road test.
Sounds like you know what your doing, similar experience to mine with the same milage I played with that little locknut till it came off lol, it should be a nylock nut on there, I took it up till the thread just started pretruding out the end and worked from there with tune ecu as i new I was close from a previous pic I took and managed to count back the threads when I zoomed in luckily, keep at it you will find sunshine
 

TURBO200R4

stand up straight and grab the world by the a$$
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Jan 24, 2013
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6,153
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TUCSON AZ
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07 rocket III classic
I live in arizona it is dusty i lube the linkage with wd40 to get the dust out.
I think there is another way i could buy new throttle bodies for thousand dollars about every couple of years.
My linkage looks bad and is in need of a car wash but it works. Lol
50,000 miles still same tps and stepper motor. Stepper motor is not working good probably need a new one or need to spray it. Still runs great when it warms up.in the past i have had the sticking throttles and the not running correct because the heat made my tank gas expand and go into the canister.
Just my opinion. Help this helps.
 

motolink

Nitrous
Thread starter
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Sep 11, 2010
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1,421
Location
Brisbane South, Australia
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2011 Roadster and 2001 Bonneville
From the best I could do I don’t think there is any clearance between the stepper motor and the throttle body linkage, it is difficult to get a good access but I feel sure there is no gap, the stepper motor rod and the throttle linkage seem to be hard up against each other. Would this indicate the stepper motor is faulty and has not retracted all the way back.

Appart from the stepper motor possibly being faulty if so would this have anything to do with the surging in have been getting, the challenges continues.
FD7CE7B6-D49D-46FF-9C3A-676CDF23F2C9.jpeg
 
Last edited:

IAROCKET

.060 Over
Joined
Apr 18, 2014
Messages
104
Location
Waterloo, Iowa
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2013 Rocket iii Roadster
Awww, come on guys, it's so simple maybe you need a refresher course. It's all ball bearings nowadays. Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads, and I'm gonna need 'bout ten quarts of anti-freeze, preferably Prestone. No, no make that Quaker State.
 

TURBO200R4

stand up straight and grab the world by the a$$
Joined
Jan 24, 2013
Messages
6,153
Location
TUCSON AZ
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07 rocket III classic
It is late in the day but i am thinking that the gap shows up when u use tuneecu and command off then it retracts leaving a gap. Also when u turn on ign the stepper retracts momentsry then extends to the tps setting of.074 (crank setting.)
 

bebsy

Finicky
Joined
Mar 18, 2017
Messages
211
Location
Pattya Thailand
Ride
2006 Triumph R3
If its idling were it should be you can count that out it's doing its job you wouldn't be, you can't visually see the gap unless you were standing on your head and to try and feeler them is tricky there's no guarantee that 5mm gap is crucial it could be a little either side and be a start point, you say it's holding at the settings John gave your for tps and idle stepper, all sounds good the stepper would not cause the surge higher up the rev range, best take it out and see how you fare with that new tps good luck
 

motolink

Nitrous
Thread starter
Joined
Sep 11, 2010
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1,421
Location
Brisbane South, Australia
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2011 Roadster and 2001 Bonneville
I notice when I have bike in neutral and I slowly start opening the throttle as soon as I reach 1800 RPM the RPM will lift to nearly 3000 RPM without me twisting the throttle. Would this be normal, this does not happen when riding.
 
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