Kawasaki Ninja ZX Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1
So i have finished rebuilding the complete cylinder head and carbs after letting the bike sit for about 3 years. After starting the engine with the choke on, it sounds great, but if i return the choke slowly to its off position, the bike shuts down immediately. If i give it throttle and then turn off the choke, the bike runs but then stalls if i let it go. I don't think its any of the jets being clogged because the carbs look nearly new and even then i cleaned them with throttle body cleaner and my air compressor. i have set my idle screws at 2 turns from bottom up.

I have noticed that one of my carbs has a vacuum piston/slide that doesn't move when i give it throttle. the other 3 do. I have inspected all pieces in that carb and the diaphragm does not seem to be torn at all. I switch diaphragms from another carbs and still, it wont move up and down. Could this be the cause for no idle? How can i check for vacuum leaks? I would appreciate any feedback. Thanks guys.
 

·
Registered
Joined
·
1,816 Posts
Did you sync the carbs? Where is the idel RPM adjust set at? You might have some shutting all the way even with the idle adjuster out because the carbs are out of sync.

Sometimes a diaphragm might not move because the inside of the carb body is tarnished from old fuel. That could cause your non moving slide. It may not be a leak at all.
 

·
Banned
Joined
·
3,608 Posts
Also make sure you blocked off the intake sync ports under the carbs. I've forgotten to block em off after a sync and couldn't figure out why the bike wouldn't idle..
 

·
Registered
Joined
·
7 Posts
Discussion Starter #5
yeah, i bench synced my carbs with all butterflies opening up in unison. the sync looks better than before.
Which ones are the intake sync ports?
 

·
Registered
Joined
·
12 Posts
I am having the same Exact problem I was ridding the beginning of this year and noticed that I didn't have full power drone then on problem got worse started sputtering and choking its self out even shut off while I was going about 50 mph on the bypass I live near so I ripped the carbs out thinking it was a clogged jet or there was gunk in my fuel bowls to no avail they were spotless then noticed a small crack in my spark plug boot on cylinder 3 bought new spark plug boot started up same thing will only idle when I'm holding the throttle still sounds sick but better then it was I'm stumped fiddled with the idle screw a little bit just at 1800 rpm and a little twist of throttle revs to the sky 1500 Rpms with a slight rev dies immediately gonna give up and take it to the shop put a grand in to new farings tires spedomoter elbow oil change fork seal and now this I will update on what ever the bike shop finds good luck
 

·
Premium Member
Joined
·
505 Posts
Angel, you need to make sure nothing is restricting that slide. I always recommend when rebuilding carbs to use some metal polishing compound and a soft cloth to polish both the bore and the slide until they are smooth and almost slippery to the touch. Then when installing them, reach in the rear opening of the carb and push the slide up against the spring and ensure it snaps back down with a satisfying "clunk". The diaphram should make it NOT instantly snap closed but it should still "clunk" closed.


Seal: sounds to me like you have a vacuum leak creating a lean condition. You need to check all your hoses and sync port caps, and also check around the manifold boots for cracks or misalignment.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #8
Thanks for you help guys. The slide is moving again. Turns out it was a poorly seated shim on my exhaust cam that might have been the culprit. I took my cams out and re-timed the chain because i was hearing some ticking under the cylinder head, and fixed the shim and bucket that was off. After putting everything back together, the ticking went away and all sliders move up and down on the carbs. Sounds better.

However, my bike still doesn't idle without choke. It may be the butterfly valves. Are they suppose to be slightly opened? What is the original factory position/clearance of the butterfly valves?
 

·
Premium Member
Joined
·
11,231 Posts
yeah, i bench synced my carbs with all butterflies opening up in unison. the sync looks better than before.
Which ones are the intake sync ports?
I will never understand for the life of me why people do this.

You need the engine running to sync a set of carbs.
 

·
Premium Member
Joined
·
505 Posts
bench sync helps get the ball rolling and is especially useful if you have split your rack. Its a base starting point, nothing more. You are correct that you have to sync with the engine running to get any real sync done.
 
1 - 11 of 11 Posts
Top