Top revs seem low?

Hi guys, I am so close to finishing the rebuild of my xj750 82. Last few issues are; The gear change is VERY stiff and I have problems getting over 50mph

I think it could be clutch slippage or exhaust back pressure..? I have removed my mufflers, leaving just the down pipes.

I have bench sync'd the carbs, cleaned them, checked the throttle cable etc. I have thought of changing the clutch cable as it was a little sticky, but after oiling it and releasing the clutch plates (they were locked when I got the bike), I didn't think I needed too.

Any suggestions please.. I don't want to give up on my bike.

Cheers

 

have you done your vale clearances, colortuned to check your mixture, vacuum sync? If the clutch is slipping you should be able to feel, hear when it does it.

 

Top-end can be affected by:

• Partially clogged MAIN NOZZLES (Emulsion Tubes)
The tiny AIR PORTS get clogged and the Carbs fail to siphon a Full amount of Main Jet Fuel.

• Diaphragm Piston "Stick-sion"
The BORE the Diaphragm Piston travels in, ... Oxidizes. The Oxidation shrinks the Inside Diameter of the Bore (ever so slightly). But, enough to hamper the Free Movement of the Piston. The Diaphragm Pistons BIND and Hesitate causing the NEEDLE Valve to NOT withdraw fully.

The Cure is to REFINISH or POLISH the Bores.
See: Clunk Test in my signature.

 

It looks like adjusting the clutch cable sorted this out? Weird..?

 

Now, ... you have Top-end back?

Yeah, ... that's weird alright.