Rpm jump at 6k

Hello all, possibly a dumb question, at fifth gear going at highway speed, if I twist the throttle all the way rpm will creep slowly to just past 6k then rev fast to past 7k, it's hard to explain the engine speed will increase as well but I am puzzled if it's the clutch slipping? Or that's like the engines power band? It will come close to 8k then move slowly to top speed 110 per gps. If it was the clutch slipping wouldn't it do it on lower gears? It only doese this when rpm is just past six thousand. Possibly the main jet taking over? I can hammer on it in first and second and it pulls hard no slipping feeling, my clutch is perfectly adjusted per manual, I found a kit online for $114 for all new Springs and friction plates, but I don't wanna wast the cash if this is normal. What is a good way to determine a worn clutch? Thanks alot, Nathan.

I have no idea if that rpm test you performed means anything.... but, once the clutch starts slipping.... they usually stay slipping at full power in a high gear:
To really find out, remove the covers, release mechanisms, springs ....take out all the clutch plates and steel plates and examine them.... and measure the thickness as per the manual, check for warpage on a flat plate .
No...? Uninterested in doing right?
OK maybe this is rough on the clutch but when the bike is good and hot, see if you can take off quickly from a dead stop in 3 or 4 gear... I would think it should just kill the motor... if it slips ... that's worn out.
best take it apart and have the new parts ready.

If the engine speed increases rapidly but the motorcycle does not accelerate proportionally the clutch is slipping. Ed

On the other hand, if at WOT and 6,000 rpm, the tach needle suddenly flies toward the redline and the front wheel comes off the ground and there arises a deafening racket as the motorcycle tries to rip your arms off as it obscures your neighborhood in blue smoke, then you must have a 1975 750H2!!!
:silly: :woohoo: :blink:

New 750 wrote: ...at fifth gear going at highway speed, if I twist the throttle all the way rpm will creep slowly to just past 6k then rev fast to past 7k, it's hard to explain the engine speed will increase as well but I am puzzled if it's the clutch slipping? ...If it was the clutch slipping wouldn't it do it on lower gears? ...clutch is perfectly adjusted per manual...What is a good way to determine a worn clutch? ....

Where "perfectly adjusted per manual" includes proper clutch push-rod adjustment, and not slipping due to using the wrong type oil, or glazed for whatever reason -- indicates replacement needed of the drive plates (aka friction plates or lined plates).

Good Fortune!

My Z1 doesn't really start making ponies until it reaches 5000 RPM and it gets stronger through the red line. Stock it was supposed to make 82 HP at 8500 RPM in 903 trim. Being I have 1X cams and a 1015 over bore, I'm getting a lot more than that. If you aren't feeling a increase in power when it revs, the clutch is slipping. If you are, it's the power band kicking in. :woohoo:
Steve

Ape clutch's work great. I run the extra plate KZ1000 kit
in my GPz750 motor.
kzzone.com/clutches.html

Like Mission says, the clutch slippage will first be noticed in high gears. That's when the clutch has the least leverage against rotating the wheel, so that's when it slips first.

Check adjustments per the manual before tearing things open.

I have an 84 kz550 that dose the same thing. It's not a clutch problem I don't think. All be cruzin around 70mph and just ease the throttle past 6k and within a few mph it will jump up to 7k. You can't hear it in the engine but you can see it on the tach. It happens pretty consistent to so I don't think it's a short.

Could your ignition advance weights be sticking up to 6k then become unfrozen and give you all your advance at once?

If the engine does not increase in rpm along with the tachometer, then it is likely to be an electrical gremlin of some sort. Have you tried the diagnostics listed in the factory service manual?