Z750 Problems

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Z750 Problems

Hi all. I have a problem with my bike that I'd really appreciate the wisdom of the VD Workshop hive mind on.

 Basically, there seems to be some kind of fuelling fault or something in the engine. Symptoms I've noticed are:-

 -Stalling/cutting out when stopping at junctions etc. Basically whenever I pull clutch in on a closed throttle, the revs drop off & it cuts out, unless I blip the throttle lots, if I've coasted in gear for a little while. It gets much better when engine is hot, but still does it at least once per ride. Had it looked at by garage, who couldn't spot a problem & claimed no known problems with this kind of bike. They replaced the FI air inlet rubbers & tweaked the idle speed which has improved things a bit.

-Reluctant cold starting, sometimes even cuts out with full choke.

-Runs pretty rough from 4,000 up and feels like power is down. Noticeably more vibes through seat, pegs and bars (although the Z does rattle a bit anyway, admittedly). This engine usually pulls hard from 7,000 or so, but it just doesn't now.

-Might be some slight hunting/surging on a steady throttle, but that could be my imagination. It is definately lurchy on closing the throttle though. And a bit wooly at small throttle openings.

-Fuel consumption is way up. Fuel warning on at about 115 miles, whereas I was used to about 160, IIRC (not tested that one for a while). Starts hunting/cutting out at 130 with empty tank now.

-This is possibly an odd one. I have one of those light-up doohickeys on the dash that tells you if your mobile is ringing. It actually doesn't work with my new phone, but I've never got round to taking it off the bike. Anyway, it always goes nuts with the flashing whenever I stall the bike (through rider error or otherwise) and I've noticed that it goes off often now when I'm just riding along. Particularly on a steady throttle in the 7-8,000rpm range. I just wonder whether it's picking up some kind of interference from a confused ECU?

Details about the bike: 2005 model Kawasaki Z750 with about 14K on the clock. Has a Remus Revolution carbon slip-on can, no remap as apparently not necessary for that can. Has a Scottoiler. Has been knocked over on its RH side, but these problems were there before that, for the most part. Is happier (but still not right) on 97/98 RON petrol.

My thoughts, from a position of minimal knowledge, are:

-FI needs remapping?

-Engine is running too rich/lean? But presumably that could be picked up easily by garage?

-Engine vacuum not right, possibly because of Scottoiler?

-Fault with FI system, possibly something like air temp sensor?

Thanks in advance for any comments that I can use to try & have the bike looked at again next time it's in for a service. I'd like to get this sorted out, because all these little niggles are starting to get frustating and making me not enjoy riding what's otherwise a great bike.

That's all I can think of for now, but happy to clarify etc/add further detail. 


Sorry for the bump people, but any thoughts on this out there? When I rode to work on Thursday morning it stalled/died about 6 times at junctions. The engine just often won't catch at idle. I'd like to get it sorted out, cos it's driving me up the wall! Cheers, R.

Without plugging it into a diagnostic computer, it is difficult to guess on this one. My hunch is that there is summat going wrong with the mixture - I would look at air-temp sensor or airflow meter first, but the computer would show the relevant fault code straight away.

I have a 2008 model Z750 and I had the exact same problem. It has to do with the choke. After a while the tension of the spring which adjusts the choke goes soft and you need to re-tension it. When you look at the bike from the left hand side while you switch the bike on you will see the starter mechanism move (It looks like a leaf shaped piece of metal) - on its bottom right side runs a small wheel atached to a lever... The wheel and lever have to run on the leaf shaped piece of metal perfectly (yours should seem loose or with some play - up and down). If this is so... there are 2 screws attached to the lever, one is directly on the lever you see and the other sits about 20cm deeper in towards the middle of the bike. Adjust these screws to make sure the lever is tight when the mechanism is in its highest up position. You should not have this problem after. If the explanation is unclear you are welcome to email me at jaco.de.klerk4@gmail.com and I can give you photos of the parts and how to adjust.

Z750 2008 dosnt have a choke. From 2003 all Z750 are Fuel injected.

did you sort out the problem,mine is doing the same [tom,lewis2@aol.com]

Hi peeps I have a z750 1990 it's starts nice and sweet but sometimes when revving the bike the revs stick I've changed the throttle cable cleaned the cards out and no leaks on the rubber seals any tips please

Could be sticking throttle slides. The cable can return but if they're vacuum diaphragm carbs then the slides could still stick. Even if the throttle butterflies are shut it can still allow the revs to hang. Could also be fuel level too high in the float bowls. Can be caused by incorrect float adjustment, or "heavy" floats (they can absorb fuel over time. Could be dodgy cold start (choke) plungers / seals allowing air & fuel mix in. Other than that I'd still spray a load of carb cleaner all around the inlet tracts up & down-stream of the carbs to double check for air leaks. The fact that it's only happening "sometimes" suggests it's not the problem, but it's by far the easiest thing to test & correct!  

If you are unhappy with your bikes that cannot be diagnosed by conventional means... then I would suggest you take it to your local "Dealer"...where he will give it to his minimum wage 17 year old spotty mechanic ..who will read a zillion faults from his computer, replace all sensors and components to ensure a good bill, and as you ride  off and it coughs and splutters, it may ocure to you that....This maybe was not a bike to buy....

I. Have zr750 year 2000 she runs ruff low down any one help

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