QuestionHi Mark,
I've just bought a 1984 Kawasaki ZX750A2 (air cooled). The bike idles fine on the choke and when just off it, but not when it's getting hot. I rode it home yesterday and for 5 - 10 miles it went fine.
After about 5 miles I came to a junction and the engine ticked over at 3,000 rpm. Then, whenever I put the clutch out the engine over-revved. After a few miles it was revving to 5,000 whenever I changed gear or was sat in neutral. Luckily top gear will handle from 20 - 100 mph + no problems, so I didn't have to change gear much. I rode 175 miles home and only had to stop 4 or 5 times. I killed the engine as soon as I stopped, and slowed to the point of stalling before pulling the clutch out. On starting again it ran ok until warmed up, and then it was as bad as ever.
The bike will run at 2,000 revs all day, but the moment the clutch is engaged / load is taken off the back wheel it races to 5,000.
At the lights it looked like I wanted a race, because I had to feather the clutch to keep the revs down. This meant I sounded like I was blipping the throttle to beat everyone away. This obviously wears the clutch, but it was the only way to keep from blowing the engine up.
The bike only has 24,000 miles and has been garaged for 9 years, so apparently had laquered fuel in the carbs. These were replaced, and seemed to be set up ok.
Any ideas?
AnswerHi Mark,
The first thing to do is adjust the idle. Next, check and adjust carburetor synchronization.
If these adjustments does not correct the problem, look for vacuum leaks around the carbs, airbox/air filters, and intake manifolds.
If there is no vacuum leaks, consider cleaning and tuning the carbs.
Learn about reading the appearance of spark plugs. Visit NGK's website: www.ngk.com
It should be noted that cylinder compression and valve clearances must be within service limits for the carbs to work properly. Check and adjust accordingly.
Respectfully,
Mark Shively
