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Live 2 Ride, Ride 2 Live
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Discussion Starter · #1 ·
Recently, on few occasions, the bike jumped few times out of a gear for a second then grabbed again while accelerating at higher rpm. It feels like a clutch was pulled in for a half a second or a gear jumped out and back it (rpm jumps up). At different instances it happened on 3rd, 4th, and 5th gear.

Other than that all the gears shift smoothly up and down. There is no grinding or any unusual noise when shifting. Clutch seems to be adjusted correctly and does not appear to slip under load. Bike has about 37k miles, clutch was never replaced. Chain slack is within spec.

Do you guys have a clue what it could possibly be?

you can hear it in the video:
Here is an example
 

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When in doubtThrottle out
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Recently, on few occasions, the bike jumped few times out of a gear for a second then grabbed again while accelerating at higher rpm. It feels like a clutch was pulled in for a half a second or a gear jumped out and back it (rpm jumps up). At different instances it happened on 3rd, 4th, and 5th gear.

Other than that all the gears shift smoothly up and down. There is no grinding or any unusual noise when shifting. Clutch seems to be adjusted correctly and does not appear to slip under load. Bike has about 37k miles, clutch was never replaced. Chain slack is within spec.

Do you guys have a clue what it could possibly be?

you can hear it in the video:
Here is an example
Worn clutch
 

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Live 2 Ride, Ride 2 Live
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Discussion Starter · #3 ·
Ok, so this past Monday I mounted a gopro to see what is going on with the rpm. After reviewing the video, I realized that my problem is different from what I had described in the post above. In my original post I thought the rpm jumps up and a gear disengages due to the fact that by the time I looked at the tach it appeared to go up (right after it dropped by about 500 rpm or so).

Here is the update: what I found is that it only happens at about 12.5k rpm, while accelerating. Rpm drops by 500 for a moment before going back up and continuing to accelerate as if nothing happened at 12.5k. Anyone has experienced anything like this or had any leads?

It happened prior and after the following service: replaced spark plugs, engine oil, adjusted valves, replaced clutch (which was still in good condition and within spec), synced throttle body. So neither of those improved/worsen the situation. Velocity stacks were also inspected and are in good condition.

Engine is stock, stock headers, no fuel management. Nothing was done to the bike prior to the issue.

Video of the tach:
 

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"The Dude abides .. "
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it's not a slipping clutch, i would have thought the same as mercenary posted earlier.. till i heard/saw the vid where rpm drops, not raises.
12,500 is about where the velocity stacks should be raising up. Have you had the ecu flashed and changed where that occurs? could be a mapping issue. How about the quick shifter, is there any chance you are hitting it with your foot as you come on to the front straight (njmp?) Is it only happening in that specific gear?
 

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Live 2 Ride, Ride 2 Live
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Discussion Starter · #6 ·
ECU was not flashed and there is no quickshifter:/ Does not cut off on a specific gear, it happened on 3rd, 4th, and 5th, the gears stay in. Only specific and common thing seems to be 12.5k rpm as it occurred on couple of instances and all at that rpm range.
When it first did it (had not clue about rpm dropping and only happening at 12.5k), I thought that maybe it was my foot pushing the shifter, but that was not the case.
 

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Meh
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Coils? Fuel injectors? Fuel pump? I'm kinda grasping at straws. It's really weird that it's so almost mechanical. Are you sure you didn't just shift? :laugh
 

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Live 2 Ride, Ride 2 Live
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Discussion Starter · #8 ·
Coils? Fuel injectors? Fuel pump? I'm kinda grasping at straws. It's really weird that it's so almost mechanical. Are you sure you didn't just shift? :laugh
Yes, I'm positive, once or twice... yea I would blame it myself for doing something, but that's not it as it happened on number of occasions where now I'm aware of it.
 

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"The Dude abides .. "
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put the dash in diagnostic mode and check all the values against the manual spec.. pay attention to the 3 or 4 throttle position tests. Make sure closed is in range, 100% in range, and look for a nice sweep of values from closed to open to closed. the butterflys are not cable driven, they are "fly by wire".. something could be off somewhat.
No codes being thrown ?
 

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Live 2 Ride, Ride 2 Live
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Discussion Starter · #10 ·
put the dash in diagnostic mode and check all the values against the manual spec.. pay attention to the 3 or 4 throttle position tests. Make sure closed is in range, 100% in range, and look for a nice sweep of values from closed to open to closed. the butterflys are not cable driven, they are "fly by wire".. something could be off somewhat.
No codes being thrown ?
Thank you for suggestion, just did it, it was a good call but it seems all the numbers fall within spec.

Results:

diag #1
Throttle position sensor (for throttle valves) signal 1:
fully closed 16 (manual calls for 12-21)
fully open 100 (manual calls for 97-106)

diag #13
Throttle position sensor (for throttle valves) signal 2:
fully closed 16 (manual calls for 9-23)
fully open 101 (manual calls for 94-108)

diag #14
Throttle position sensor (for throttle cable pulley) signal 1:
fully closed 16 (manual calls for 12-22)
fully open 100 (manual calls for 97-107)

diag #15
Throttle position sensor (for throttle cable pulley) signal 2:
fully closed 15 (manual calls for 10-24)
fully open 100 (manual calls for 99-109)

There are no fault codes on.
 

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Live 2 Ride, Ride 2 Live
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Discussion Starter · #12 ·
Did you ever get this figured out?
I did not figure out what the cause was. I went thru diagnostics, checked coils one day, and primary and secondary resistance was within spec. After that the bike still had symptoms. Then it stopped doing it. So far so good, I did about 1k miles and no issues. At this point I doubt it could have been mechanical or electrical issue as those would only get worse and wouldn't fix itself. No clue what could have caused it, maybe something was clogged (line, an injector).
 
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