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Discussion Starter · #1 ·
Firstly hi all !

I found this forum threw d kleins very useful STVA fault thread.

Seems like a grate site so a big hello from london UK.

I have a 2005 GSXR 750 that i bought new and have done 30000 miles on so far.

I was changing the air cleaner today and thought id run the STV checks described in the manual.

so..

before i hit the run switch with the ignition on the valves seem to be about 95% open as per the manual.

with the run switch turned on the valves try to open more! hit 100% the servo makes a clicking sound and then the valves return to 95% open.

According to the manual this is wrong, they should in fact first shut completely and then cycle to the 95% open position .

If i close the valves by hand then hit the run switch they cycle all the way open, the servo clicks and then they return to the 95% open position.

if i remove the STPS and hit run then valves close completely, the servo clicks and they stay there.

i must add i havent been getting an F1 light from the bike i was just running the test and it seems that there is something wrong.


It seems that the STV's are not working at all and that the bike is just running with them at 95% open all the time.

The bike starts and runs but has little engine braking and also "chug's" a fair bit at small throttle openings.

Im not to bad with general mechanics but electrics have my head spinning!!

i only got a multi meter 3 weeks ago! but im keen to learn so an help would be grate.

iv tried to test the resistance on the 4 pins of the STVA but to tell you the truth i cant make much sense of the readings as im a multi meter newb :)

the reading just seems to go up and then strait back donw to nothing..


like i said if anyone can shed light on this it would be a great help


Adam
 

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Welcome, Adam. I have no idea what you just said, but maybe someone here does. ;-)
 

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Fiction, the wording in the manual is somewhat dicey as far as the STVA diagnosis goes; When the switch is set to "Run" with the ignition on, the valves should begin in a closed position before opening completely, then cycling back to an "almost closed" position (this is the 95% that they're referring to in the manual). This is the "whirring" noise you'll hear every time you prepare to start the engine. These valves open as you apply throttle, and remain mostly closed during idle. Since your valves are open from the beginning of the cycle, the STVA was installed with the incorrect key position between the STVA and the valve shaft.

The secondary throttle valves and actuator both have limited travel within a range of about 90 degrees, so if the STVA is installed improperly, the valves won't open and close as they should. The fix is easy. (NOTE: the steps in this procedure are done on the right side of the bike, facing the engine).

Remove the STVA once again, and rotate the keyed inner bushing all the way clockwise, holding the unit in-hand in the same position it would be mounted on the bike. Next, fully open the secondary throttle valves, so that the keyed shaft matches the key position on the STVA. Install the STVA, close the valves by hand, then test the operation as described in the first paragraph. The whole key is to make sure that the limit of travel on the STVA matches that of the throttle valves before reinstalling the STVA. There are only two possible ways to install the STVA, so your fix should be pretty simple. Good luck and let us know how it goes!
 

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Discussion Starter · #6 · (Edited)
Thanks dude, it dint seem right to me and the bike isnt running right.

ill give it a try and let you know how i get on...

if it is installed wrong then the factory did it as it has not been removed by me of anyone else that i know of.

i have removed the STPS in order to replace the PTPS but not the STVA
 

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Had a similar fault, got a replacement SVTA on a well know auction site :) tested and 7.x on the meter, so all looks good also did the repair de-solder etc according to D-Klein destructions and again 7.x on the meter. However I cannot get the bloody valves to cycle at all...

Wonder what else I broke... :( not a happy biker.

Any help, appreciated
 

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I dont think you will get any answers from the OP or D_klein as both were several years ago and neither have been on the forum for a long time. However the secondary throttle valve problem may be a simple fix....hope so. here is a copy of someone who found a simple solution....

Over the last couple of weeks I have been getting the dreaded C28 fault shortly after start up. Sometimes just stopping and restarting cleared it but in the last couple of days it became more persistent. Anyway I scoured the forums, Haynes manual etc and have now fixed it but wanted to share my experience with other members as the fix was far easier than the rabbit hole I was about to go down. It's a bit embarrassing (especially as an engineer but in my defence I am new to bikes) but the moral of the story is keep it simple and don't forget the basics.

When the FI fault displayed I made a jumper cable as described in other threads and found the dreaded C28 code showing. I duly did internet research and consulted the Haynes manual which told me to check the resistance and continuity of the STVA motor. I had infinity to ground and 16 Ohms across the motor which is outside of the 7-14 (approx) expected range but only a little bit. These readings were found to be constant as I worked through the wiring to the ECM. Continuity from the STVA connector to the ECM was also correct.

The fault diagnosis and internet advice was then to investigate maybe using another ECM or replacing the throttle body. I thought I'd also maybe try to drive the motor by putting a false signal to the motor and starting looking at that. Whilst I was looking into the what I would need to do if I changed the throttle body I came across the bit about STV synchronisation in literally the paragraph before the one I started at a couple of days ago. Here I found about moving the valves via the nut on the end of the gearbox, I knew not to try working the actual butterflies by hand.

That was the eureka moment where I realised I had jumped in too deep with multimeters etc without a simple check of will the valve turn by hand.

Anyway, I tried turning the nut using just my fingers but found it a bit stiff so using an 8mm socket I slowly worked it open and shut between the stops. I then powered up the ignition and the STVA moved (only a little bit and quite slowly) and I knew I was on the right track. With the use of WD 40, hot soapy water, a nylon brush and some moly grease I was able to free up the whole mechanism and now it works perfectly.


So my advice is, don't assume the worst and check the basics as you may actually be lucky like myself and not need to replace expensive components.


Good luck
 
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