on/off throttle surge gsxr750

Let's say I am on the Dragon on my '06 gsxr 750 and riding in second gear and when i approach a corner and let off the gas ...the bike seems to drop its rpms like it is going to idle speed and then when i need to get back on the gas it is a bit abrupt on the re-engagment.

I have a PC3 that has been dyno tuned with a great map....what I am wondering is if this could be slipper clutch or drive train issue with the sprockets or cush drive....where there is slack and it takes a moment to re-engage?

Quick history...bought bike with everything on it (i.e PC3) took to track for first ride and baughed (sp?)coming out of turns really bad, friend said sounds like PC3 and noticed Cylinder 1 exhaust pipe cold vs others. So disconnected PC and still crappy running...changed plugs and seemed to fix the problem. i do not think it had this surge issue while in stock form but honestly do not remember..

So crash at CMP last november...fix bike and get the PC3 reconnected and dyno tuned. put 2,000 miles on it with this surging issue. Take it in to get retuned thinking its a map issue....get it back ride it and cuts out on me like at track day...ease it home...get FI code on dash...then ride it again to see what code it throws C34...injector code and runs crappy..then check all plugs fro PC lift tanks make sure everything plugged in...ride for another hour with no issues, but surging issue still present.....

It is like I need to turn the idle speed up so the rpm's do not dive when I am off the gas...

Anyone got any suggestions as to whether it is the MAP? or Bad PC? or clutch issue? or Drive train?

Thanks

Scott

 

bump

HHMM no one has experienced this before....

 

bog is what you mean I think.

You can turn the idle up to 1400 or so if you like.

sounds more like feuling issue than anything else.

check throttl eposition sensor for PC3 and make sure its hooked up.

you should be able to push the chain to the bottom of the swingarm. make sure its not to tight or loose.

you could also check that injector.

 

there is no idle adjustment and yes BOG is what I was trying to say but could not figure out how I would spell it for some reason.

Chain is good...
would the TPS be the problem if it is not set corretly?

Thanks for the suggestions...

 

Go to gixxer.com and do a search for herk and jerk, sounds like what you are describing.

 

Try a Bazazz or Ivans TRE. The computer reads the gear and retards timing in 1-4 in lower rpms at partial throttle. That makes trailing throttle jerky.. You can't fuel tune it away.

 

So the PCIII is the problem? Why have not more peopel had this problem? or is it that they just live with it?

Thanks again and I think I will give Ivan a call.

 

My 750k6 tps required adjustment from the factory. Definitely worth a look.

 

Dis-connect the PCIII for a session and see what happens to find your problem.

 

The PC is not a problem. The stock ECU reads the gear position from the sensor ( remember you have a gear position display) and in gears 1-4 retards time at lower rpms.... The TRE (timing retard eliminator) just sends a signal to the ECU that the bike is in 5th all the time.

 

OK so this should still happen even if I disconnected the PC3? Sounds like I need to disconnect PC and then ride it to see if it is still present.

Thanks again...good stuff

 

PC can not fix the ECU program. Disconnect it and the problem will probably still exist.

 

OK last little question. Is this a problem most have or just some GSXR bikes? I am surprised off all the people I have talked to that nobody has this as an answer.

This forum is AWESOME!!!


I hope this is my issue...

 

This is a fairly common GSXR issue. Turning the idle up will help (2200 or so). Adding a TON of fuel at 0-2-5% throttle in your PC map (at the RPMs that you are getting back onto the gas, 4000-7000 maybe?) will also help a ton... and last but not least, carrying more corner speed so that your RPMs are not so low when you get back on the gas will also help.

 

I had the same issue. I cured it by adjusting the TPS a tad above center line on the dash.

 

thank you...

 

no problem. let me know if you have questions about the procedure

 

All I can say is if this fixes the problem and is simple to do then I will be extremely happy.

I have a service manual at home so I was going to read up on how to set the TPS....but if you have a quick 1, 2, 3 go procedure then I will take it.

 

check this thread out on gixxer.com: http://www.gixxer.com/forums/showthread.php?t=185499&highlight=herky+jerky

This is exactly what I did to cure my abrupt throttle. Before this I tried everything from tuning my PCIII to disconnecting it all together. This problem drove me crazy when we went riding in the twisties. It got so annoying that I almost lost all intereset in the bike.

 

I'd think long and hard about adjusting the TPS without doing a four gas dyno run and seeing how much power you lose and what happens to the exhaust gas. The TPS tells the ECU how much throttle you are using. If you adjust it to show "more" ( thus eliminating the timing retard) you also change the parameters of the fuel delivery.