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Discussion Starter #1
Hope someone can shed some light on this issue. In 6th gear at between 4-5k revs I am getting a very slight lag then a big clunk at the back wheel ( enough to make the rear, and my arse twitch).
Once through the revs it runs smooth again.
I have tried it when changing up from 5th, when rolling on from lower revs in 6th and when throttling back in 6th (it doesn’t happen as the revs are lowering through this range) and opening it up again.
It only happens at this specific point and the bike runs fine at all other times.
Ive checked the chain and sprockets which are in good condition and correctly adjusted. Not sure why, but someone has put in JT 16 tooth front and 43 tooth rear, which I don’t believe would create this issue. Also checked the Cush rubbers which are fine.
Im waiting for delivery of a new standard chain and sprockets and a service kit including new spark plugs which I will be Fit on arrival.
Does anyone know of an FI or sensor issues that could cause this?
 

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Does the front sprocket "float" properly on the splines? To check, take off the cover over the front sprocket. Sprocket should move freely in/out or axially about 2mm. If the splines are dry the sprocket will stick then clunk and grind around.
 

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Discussion Starter #3
Does the front sprocket "float" properly on the splines? To check, take off the cover over the front sprocket. Sprocket should move freely in/out or axially about 2mm. If the splines are dry the sprocket will stick then clunk and grind around.
Front sprocket has the normal freedom to move slightly in both directions. 👍
 

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It wont move freely under load if the splines are dry.
Absent internal damage to the gearbox, is the rear sprocket lined up exactly in line with the chain?
The chain may have hidden damage.
Something wrong with the clutch.?
rear tire damage?
Rear wheel bearings?
Electronic glitch? ??? Can you replicate this issue every time ?
Can chain tensioner. These can vibrate wildly at (usually) 4000prm when worn.
 

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Discussion Starter #5
I can replicate every time, and the problem is only in 6th gear at 4-5k revs every time. Otherwise bike rides great.
No vibration.
sprocket is aligned
Chain appears undamaged
No obvious issues with wheel bearing.
Tyre is in good condition.
???
 

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As you are replacing the chain and sprockets soon maybe it will go away? Use anti seize on the splines.
6th gear at 4-5k revs = certain speed range. This is most likely speed related not rev related. Something amiss with the running gear. Something is loose, or has hidden damage?
 

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Thinking a chipped gear tooth but agree with Fizzy. Let's wait until you get the chain and sprockets swapped.
 
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