Motorcycle Repair: Z650 not reving above 5000 rpm, excessive smoke, cylinder compression

Question
Renovating a 1977 Kawasaki z650c2 and can't get the bike to rev past 5000 rpm on the road. Have checked points gap and timimg, also cam timimg and shim gaps. Have new plugs fitted and even used 2 sets of carbs with different MJ sizes (from 102.5, 105 to 107.5) but get the same problem. Using standard 4-2 exhaust. No excessive smoke from bike when running and all cylinders are firing. Bike starts and idles fine. Any offers?

mark@gt380.co.uk


Answer
Hi Mark,

What is cylinder compression readings? <-- First thing to check.

Second thing to consider is an intake air restriction/obstruction.

Third, read spark plugs to learn what changes need to be done with air-fuel mixtures (jetting) if any.

Respectfully,
Mark Shively
Dayton, Ohio, USA