A real head scratcher....

Forget about doing a compression test cold. These bikes are old air cooled grumpys. Huge gaps in some until hot, then the compression really comes up.

Maybe time to take the carbs off and completely dissasemble. Check everything, and make sure that carb cleaner blows the same through all passages. (Make sure no rubber in there during cleaning)

Valve clearances should be checked anyways as its considered regular maintenence on these old guys.

Check carb boots, no air leaks.

Check pilot screw settings, correc.

Tune-up, roll out.

Good luck, cheers.

yeah new plugs are definatly on the list, i hadn't gotten to the KZ at all last week but should this week. one question maybe i'm just having a brain fart but would a normal automotive timing light work on the 900? as long as i have it on the no.1 plug wire right?

pretty sure it isn't bad gas. and yes i agree the 10% ethenol(alcohol) is not that great for older engine period. in all honesty it's not really good for most newer cars either lol! i always buy gas from stations that don't have ethenol even for my cars and preferibly at shell stations. i guess as an FYI check out toptiergas.com it has a long list of recomended fuel suppliers that don't have bad gas. i;m somewhat picky about the gas i use.

and already had the carbs all apart from the bowls down. cleaned and verified all passeges are clean and working.

yep,some lights ned to be adjusted depending on number of cylinders

okay so i got around to messin with the bike. i checked all the valve clearences and they are all well within spec, if not a bit on the tight side. but definatly uniform in measurments and within the spec that i have from the clymer manual. performed another compression test with a squirt of oil in each cylinder and the throttle wide open. it came up with almost exactly 100psi on all 4 cylinders. which i found in the clymer manual it says that 100psi is the maximum serviceable limit. the spec is 145psi. but like i said this bike has some miles and everything was cold. haha and when i mean cold it was like 50 degrees outside maybe.

so next on the list is a new set of nkg plugs. if that doesn't clear up my problem it may be time to rerecheck things.

Maybe I missed it but I see no mention of the coils themselves... How'd they check out (meausurements)?

Maybe I missed it but I see no mention of the coils themselves... How'd they check out (meausurements)?

+12Vdc or higher to them?

Bryan1970 wrote:

okay so i got around to messin with the bike. i checked all the valve clearences and they are all well within spec, if not a bit on the tight side. but definatly uniform in measurments and within the spec that i have from the clymer manual. performed another compression test with a squirt of oil in each cylinder and the throttle wide open. it came up with almost exactly 100psi on all 4 cylinders. which i found in the clymer manual it says that 100psi is the maximum serviceable limit. the spec is 145psi. but like i said this bike has some miles and everything was cold. haha and when i mean cold it was like 50 degrees outside maybe.

so next on the list is a new set of nkg plugs. if that doesn't clear up my problem it may be time to rerecheck things.

100 psi? Are you sure. I did a pressure test on my '78 kz1000 few days back, and just for pure curiosity left the throttle closed and kicked and kicked and kicked and got to about 100psi in all 4 bores.

Then I went back and cracked the throttle wide open and got to 140psi on each.

100psi, wow man that sounds low. Maybe new rings are in order...?

I did my test outside, the bike's being kept outside under a cover, so it was in a stone cold state for the test, I used no oil in the cylinder, just for comparison to your situation. Also, this bike has 28,500 miles on it and half the valve clearances are less than the minimum clearance of .05mm and I'm getting ready to fix that directly.

if i didn't mention it i should have. but with the bike running(poorly but running) i have between 14 and 13 volts at both coils, which i compared to the source voltage with it running and there is no diffrence. and with the two cylinders that are persistantlty misfiring they have seperate coils.

yeah 100 psi is as low as kawasaki says is okay. and i know it isn't good but donlt think that is the source of the problem. hopefully new plugs will magically take car of my problems haha. oh well i will keep updating as i go