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Discussion Starter #1 (Edited)
Hey guys new to the forums
I ride a 2008 GSXR 600 I have had this bike for 2+ years. Bought it new. Havnt had a problem till just recently. Im hoping its not something isolated to this bike... and that it may be a known issue...

Background info...
This is my third bike, first time I bought one brand new.
I broke the bike in as per Owners Manual, serviced the bike on schedual all times. sitting at just under 18000km
I just replaced all the fluids and had everything check, also a new air filter only days ago.

I am getting a sudden loss of power, like the bike is bogging down, followed by a sudden burst of power. I have been able to trouble shoot this by closing the throttle once i feel a loss in power, and then resuming throttle. Or by pressing then relaesing the clutch.
The only problem is that it happens frequently and consistantly.
The problem also doesnt seem to start right away, but roughly 10 mins. into a fresh ride.
And there is NO fi Light.

I seem to have no problems with the bike in 1st or 2nd gear.
gears 3-6 however do. That also being said as long as i keep above 8000rpm i dont experience any loss of power.

3rd gear seems to be the worst. If i hold a steady speed between 4-7k/rpm it will all of a sudden begin to lose power from 7k/rpm to about 4k/rpm, it is then followed by a burst of power and an obvious almost violent jolt forward.
4th gear is almost the same as 3rd, with less of a jolt
5th again same with reduced jolt, usually begins loss of power arond 6k/rpm-6.5k/rpm
6th gear is by far the most bareable, usually dont experice any loss of power lower if i remain above 6.5k however it has happen. sometimes i cant even notice. I think it may be related with the speed.

Anyhow, as long as i stay above 8k/rpm im good, but this is really starting to worry me, as i have experienced this in the corners of turns in 3rd gear. also its really annoying when your just trying to cruise along at the speed limit.

I hope any of this information is usefull and that someone with superior knowledge can give me some advice and point me to a realted or similar issue that has been trouble shooted.

I am not opposed to taking it to the deealer or a certified M/C mechanic. just wanted to know if there is anything i could do to resolve the issue myself. And of course knowing what to expect to hear from the dealer/mechanic.

Thanks a bunch
 

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it could be due to bad gas. Injectors could be gunked up. id try that first then go from there spark plugs, weak spark, etc.
 

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WOW I'm going through the exact same S*** dude no way!! I started experiencing this after I replaced my spark plugs and cleaned out my airfilter did the oil change and brakes. Did you do any of these? cuz we might have the same problem ... I was thinking It might be the oil just my opinion I'm going to do another oil change and I'll let you know if thats it. ...to me it feels like the exhaust has a leak though thats what I thought it was at first but I removed the fairing and everything look normal so I'm stuck in the same problem as you
 

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You guys try adjusting the TPS?
 

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Odd that is runs weak under no/light load and has power in the higher rpms. I honestly am not sure where to start on this one and the fact it isn't a constant problem makes things even more difficult to diagnose.
 

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Mine started to happen after they painted my bike...because while everything was getting painted i got new spark plugs, oil change, brakes, and cleaned out the air filter...what I think happened was that they didn't use synthetic oil...just my 2cents
 

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The '08s seem to have a problem with failing 02 sensors. When they fail, the symptoms seem to be what you're experiencing. Check there first.
 

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oil shouldn't cause an issue like you are describing. It seems to be an air/fuel or timing issue. The TPS is a good idea as well as 02 sensor. Good luck.
 

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The '08s seem to have a problem with failing 02 sensors. When they fail, the symptoms seem to be what you're experiencing. Check there first.
bad O2 sensor would explain the loss of power at lower rpms and everything straightening out under heavy throttle. Assuming they work like cars once you hit certain % of throttle the O2 sensor isn't used any more for the air/fuel mix.
 

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Discussion Starter #11
WOW I'm going through the exact same S*** dude no way!! I started experiencing this after I replaced my spark plugs and cleaned out my airfilter did the oil change and brakes. Did you do any of these? cuz we might have the same problem ... I was thinking It might be the oil just my opinion I'm going to do another oil change and I'll let you know if thats it. ...to me it feels like the exhaust has a leak though thats what I thought it was at first but I removed the fairing and everything look normal so I'm stuck in the same problem as you
Yea its strange, i have gone through multiple tanks of fresh gas, no FI light on, changed all my fluids days ago switched to synthetic, new air and oil filter. when the oil was drained there was nothing in it and the mechanic said thats a good sign its not mechanical.
Im guessing it might be a sensor or something.
 

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Discussion Starter #12
Odd that is runs weak under no/light load and has power in the higher rpms. I honestly am not sure where to start on this one and the fact it isn't a constant problem makes things even more difficult to diagnose.
It is definitley a constant problem. It happens all ride.
 

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Discussion Starter #13
Yea i was thinking it was an Air/Fuel thing, thats why i preplaced the fileter, as it was really dirty.
Im going to check the o2 sensor and the TPS too
You guys are awesome thanks!
 

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hey guys I have a 2008 gsxr 750. I had a similar problem when cruising at steady throttle around 4-5k and come to an incline, I would start to increase throttle and the bike would bog down then all of a sudden "take off". After a little research I heard that the exhaust valve has had problems on other gixxers. So I tried removing it and I have not had the problem since. Worth a shot, simple to remove but you also have to terminate the connection for the actuator at the pcm or the FI light will turn on. You could also just disconnect the cable to the exhaust valve as an experiment then the pcm wouldn't know the difference. Like I said, fixed the problem on my bike.
Hope this helps.
Cheers
 

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Discussion Starter #15 (Edited)
hmmm so many possabilities... i dont know which to check first...
TPS?
O2 Sensor
or Exhaust Valve

Im going to adjust the TPS tomorrow after work and see if that helps, found a great post on the forums. I will update you guys on the situation as soon as im done.
Now in regards to the O2 Sensor can anyone give me any information on how to check/replace this, where it is on the bike and if there are any writeups on this already :p
and what would the effects of disconnecting the Exhaust Valve?
 

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hmmm so many possabilities... i dont know which to check first...
TPS?
O2 Sensor
or Exhaust Valve

what would the effects of disconnecting the Exhaust Valve?
My bike was doing the same as you described in your first post. Cruising along part throttle keeping the same speed then if you came to an incline and needed to accel slightly the bike would bog down then all of a sudden a burst of power. This is my take on the problem. While cruising the exhaust valve closes down( there is still a small hole in the exhaust valve plate) to reduce noise and emissions. Next while you try to accelerate the exhaust valve tries to open but is sticking. The actuator continues to try and open the exhaust valve but can't, then all of a sudden the valve opens resulting in a burst of power. I didn't notice any effects of removing the exhaust valve actuator other than the exhaust note was slightly louder at idle. May be small loss of power in lower rpms but barely noticeable. When the exhaust valve is disconnected it defaults to the open position because it is spring loaded.
Hope this helps.
 

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im with senojrb on this. bypass the exhaust valve and try to duplicate the problem. im willing to bet money thats what it is. but if im wrong, my second guess would be the tps sensor.
 

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Discussion Starter #19
I have been trying to troubleshoot the issue, So far i have changed all the fluids, switched to synthetic oil, put in a new air filter and checked the spark plugs. So far none of that has resolved the issue.

Now as suggested by someone else I have also adjusted the TPS as per this thread...
http://www.gixxer.com/forums/showthread.php?t=185499&highlight=tps+adjustment

My TPS was defiitley way off and after I adjusted it accordingly I went for a test drive. And unfortunatley the problem still presist.
However I find that the bike is much more responsive and does better at battling the sudden loss of power.

For some of you the TPS may be an issue. I highly suggest you check as per the thread i linked earlier. and if adjustment is needed do so if you can.

Now all that being said I am inclined to agree with some of the other post that it may be a defective O2 Sensor. Again if you have the know how to check them, you may want to try that after you adjust the TPS.

Im still trying to figure that one out myself. and if replacing an O2 sensor is something that I can handle, or if it is something I will have to take to the dealer/mechanic.
 

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Discussion Starter #20 (Edited)
My bike was doing the same as you described in your first post. Cruising along part throttle keeping the same speed then if you came to an incline and needed to accel slightly the bike would bog down then all of a sudden a burst of power. This is my take on the problem. While cruising the exhaust valve closes down( there is still a small hole in the exhaust valve plate) to reduce noise and emissions. Next while you try to accelerate the exhaust valve tries to open but is sticking. The actuator continues to try and open the exhaust valve but can't, then all of a sudden the valve opens resulting in a burst of power. I didn't notice any effects of removing the exhaust valve actuator other than the exhaust note was slightly louder at idle. May be small loss of power in lower rpms but barely noticeable. When the exhaust valve is disconnected it defaults to the open position because it is spring loaded.
Hope this helps.
Hmm I would like to try this as it sounds like somehting i may be able to do myself. Would you be able to explain to me in detail how i can disconnect the exhaust valve and how to terminate the connection for the actuator at the pcm.
 
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