Hi all, I'm after a little advice about my Kawasaki ZZR1100. It's a C1, 1990 model. It will start and run but when the throttle is opened, even slightly it packs in, as if there is not enough fuel going in. On that logic I've tried, 1. The fuel tap itself. Working fine. 2. Bypassing the fuel relay (straight from the + battery terminal to the fuel pump. No improvement. 3. Removing a pipe from the discharge of the fuel pump. Fuel flowed when the pump was running. 4. I have replaced all the fuel in the tank, thinking it may be old, and added fresh super unleaded. 5. I've tested the fuel pump relay and although it seems to be different to the reading suggested by the manual surely thats irrelevent as the problem exists when it's bypassed. I have had the tank off recently for a major service (forks out and rebuilt shock, oil, chain, tyres etc and so have had the airfilter box out but can see no obvious pipes or tubes that I've disturbed. There's been suggestions that the kill switch may have bared wires which short out when the throttle opens, but they seem ok. There also seems to be a belief that the small(ish) pipe which goes from the centre of the air inlet (front of the fairing) to the carbs separately from the main air feed through the airbox and filter may have been disconnected but surely when it's stationary that should make no odds? The air pressure at the front of the headlight would be the same as surrounding the engine. I've tried running the engine both with and without the air filter cox on anyhow. The only work I've done on that part of the bike was swapping the air filter. Could I have somehow allowed dirt from the tank to enter the carbs? Thanks for your time folks! Ian
Check the kill switch anyway (my C1 kill switch gave me problems until it was replaced under warranty) But also as it is a 23 year old bike I reckon there is a good chance the carbs might need a damn good scrub......and IIRC, the carbs were CV type with the big diaphragms.......could even be they are split and not lifting when you open the throttle. AL
I last it running well not two weeks ago though. Would there be enough damage / splits to enough diaphragms caused in a short space of time? I haven't disturbed the carbs....
Gut feeling Ian......if the bike is that old and it has stood for a while, perhaps; then firing it up and the old age stiffened diaphragms have obviously moved, they could well have split, I guess....I could be wildly wrong, but it would be the first place I looked. AL
Thanks for your ideas, which I'm taking on board. However the bike has been in regular use, and only stood for a couple of weeks while I overhauled the suspension, fluids etc. it ran well after all that, and ran earlier this month before I whipped the airbox off to see the state of the carbs. I disturbed nothing I didn't need however. I'm thinking when I put it back together to try the throttle from the carbs themselves before i connect the cables so if it IS a fault in the switchgear it shouldn't matter.
I doubt if 23 year old diaphragms will be very healthy........ But whip the airbox off, start the engine and blip the throttle to see if the slides lift up..... Perhaps you got the cables the wrong way round? :wink: If it was dirt in the carbs it would have to be a serious amount to prevent the engine revving a bit....let's face it, there are 4 carbs, so I wouldn't expect them to all get an equal share of dirt from the tank. I can't recall everything about mine, but I am fairly certain there was a fuel filter somewhere....if that is blocked, then maybe there is a starvation problem........have you checked where the fuel hose connects to the carbs?....on my SS there is a tiny filter right at the tee-piece that joins the two carbs....I wonder if you have one or two of those that have blocked. AL
possibly water in fuel water in float chamber sits at bottom until revs increase then sucks up and blocks jets i.e engine dies drain carbs see what comes out ............ worth a try............
Thanks for the suggestions people! I ran it dry when the problem first started, and thinking it may be dodgy fuel ditched the 15 litres or so that i'd got in it and added new super unleaded. Like you Arquebus i find it hard to believe that all four carbs would block with dirt enough to prevent it running. I hadn't at that stage removed the cables. When the throttle is blipped the slides seem to try and lift and flutter slightly, then shut again as the engine dies. I've checked the fuel pump and filter, and both are functioning ok. I think the next stage as Johnboy says is to drain them and see what comes out. If that seems to have done no good I'll either strip and service them or get my local garage to. There seems to be a lot of tiny bits in there.... It's sending me to drink as it is!
Apart from the fact that diaphragms with small splits would cause a partial lift, obviously fuel starvation wouldn't allow the engine rev, so as you appear to have identified so cr*p in the fuel....... AL
Thanks folks. The bike is in bits at work at present in bits so ill try checking the carbs for crap tomorrow. I'm running out of ideas, to be honest!!
Check that the breather in the tank filler cap hasn't got blocked. Starting the bike will begin to cuase a vacuum and a whiff of throttle will stop any more fuel flowing. It could well have run perfectly well before the tank was removed and then picked up an obstruction Good luck
I've tried running it with the fuel filler open, no joy! Thanks for the ideas though, please, keep them coming....
I've had the carbs off and could find no snags. I then tried rebuilding the bike and trying it at each stage. With just the fuel connected and my hand operating the throttle And choke from local (cables disconnected) it ran fine. With the cables reconnected again it ran fine. And finally with the airbox connected and bodywork replaced it still works. I'm totally baffled! I've done a couple of shake down runs (not too long as it was raining!) it's working. As I said, I'm totally stumped. I'm pleased its sorted but wish I knew why it'd happened...
I always like to see what the cause of a problem was, but sometimes it just doesn't happen....................... ........but....go on, admit it..........you had the throttle cables the wrong way round :wink: Anyway........if it will still spin the rear wheel at 70mph in 4th gear and lift the front at 90mph, plus still do 0-60 in 2 seconds, it's working fine..... AL
