Join Date: Apr 2006
Location: GREECE & USA
Motorcycle: Suzuki GSX-R, Honda VFR, 1971 CB750, 1976 OMER 50 sport, Aprilia Habana
SET Valve, TPS & herky jerky fixes. DIY
Although not experiencing it (maybe 3-4 times in over 2 years) I have been reading about the herky jerky and TPS fix or masking. So I wanted to throw my 2c.
Some people claim if you move it between the middle -C00 and upper position it fixes the herky jerky.
So I tested mine today. (factory setting, never touched it and don't experience the jerkiness)
When I turn on the bike it is on high
When it warms up with correct idle (about 1200rpm) it moves to the middle.
When I ride with dealer mode is the most interesting thing.
When I pull on the gas or cruise it is on high.
When I let go (decelerate) or pull in the clutch it is in the middle.
It never goes to the bottom.......it should never go to the bottom. If it does there is your problem
All in all this makes be believe that the people suggesting to have it in the middle with a tendency to go up are correct, and that must be the correct setting to resolve to abrupt fuel cut off that creates the herky jerky to some.
Also, if many suspect the SDTV as a problem for the herky jerky, why isn't anyone adjusting the STPS? I will post a picture with correct settings as well.
I got the SET valve code (-C46) a few times since dewinterizing it and noticed the valve was not moving all the way.
Although the old trick (loosen the bottom cable 2-3 turns) that I had suggested had worked for a couple years for me and many others, it was time to do it professionally.
Sorry no DYI pictures but I will post what the manual says. In the past some told me that it look very complicated, and I will admit on paper it looks that way, but it is not.
Pretty much there are 2 harnesses coming out from the SET valve motor.
On the one connect a volt meter (positive on yellow and negative on brown/black) and look at the readings. (that is the 3 wire harness) Make sure it is the back side of the connector, not the side towards the motor, those are different color wires.....see picture
Disconnect the other harness (2 wire) and apply 12 volts to it. Take it with 2 wires form the battery. When applying one way the set valve closes completely. (12v+ on the pink wire) then immediately remove the power to the motor and look at the volts from the other harness where you have the volt meter connected. You need to turn the bike on for that, including the kill switch to get the correct reading. If not OK adjust the top cable.
To adjust in open position, just give 12v to the other wire and negative on the pink wire), same procedure but adjust the bottom cable only this time.
Closed should be between 0.5v and 1.3v -----I did mine at 0.95v
Open should be between 3.7v and 4.5v ------ I did mine at 4.1v
You adjust the volts by adjusting the wires next to the motor. The top cable is very sensitive....be patient and careful
Obviously this is the resistance the motor has to sense to stop moving. Mine was at 4.5v open and 1.2v closed, obviously very close to the end of specs so any discrepancy (usually happens when the wires get hot or the exhaust expands....that is why most people see the FI after restarting the bike when hot) would read wrong, the valve would not fully open or close and the FI light would come on.
The results are GREAT, perfect movement and power from the bike.
Yes it will take you 30 minutes + removing the cowl, but like I said no more FI light, smoother throttle response and great performance results.
My guess is that most are not adjusted to perfection form the factory and that is why many see the FI light, or claim that disabling the SET gives the better performance.....it does not in both conditions the valve is fully open (if adjusted right)!
Here are the pages from the manual.....don't be intimidated, it only looks complicated.
Another note, to adjust the wires, give a little opposite 12v power to the motor so it loses the wire, then open or close fully and check again.
When all done and checking the calibration process, mine was showing 1.84 volts when the motor stops so just under half way open before you start the bike.
Edit: The second adjustment was performed today after another 7500 miles. Numbers were close, closed was 0.88V ...I adjusted it to 9.5v and 4.11v for open. After the calibration process the reading now was 1.77volts.
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Last edited by ZaXoS; 04-22-2009 at 12:20 AM.
Reason: Too may people inquiring details. Added details and picture