Kawasaki Sportsbike Riders Club - Australia - Online Forum

Well the other day i cleaned out my carbs one my bike ('92 Kawasaki ZXR750) because i was advised to do so by the mechanic that serviced it.
So after I had cleaned them i reinstalled them and what do you know, the bike is really hard to start.
Eventually i got it started and it would stall straight away. Fixed the idle adjustment and it stayed lit. But today, 4 days later it wont start again. Now though when it gets near to starting, an almighty bang will come out of the exhaust. It definitely does not sound good, sounds very concerning. Then stalls again.

I am pretty sure i have done nothing wrong, just that i haven't done something. What that is i have no idea.
If anyone can help me out and possibly shed some light onto the matter, it'd be greatly appreciated.

Regards

Matt

HI Matt best bet would be to pull them off check all the butterflies & working parts put the carbs back on carefully checking that they seat properly etc *& see if that work for you........+ sounds like it could be a fuel blockage... see how much fuel comes out of the float bowls when you pull em back off

Yeah i have no idea how to tune them or how to tell if they are under/overfuelling but my uneducated guess is its overfuelling because it finally started and was puffing fuel smoke out the back...
When i reinstalled the fuel supply hose i accidently split it so i replaced it with a smaller hose (went form 5/16 to 1/4), so im not sure how that would effect it if anything.

Specwarop wrote:Yeah i have no idea how to tune them or how to tell if they are under/overfuelling but my uneducated guess is its overfuelling because it finally started and was puffing fuel smoke out the back...
When i reinstalled the fuel supply hose i accidently split it so i replaced it with a smaller hose (went form 5/16 to 1/4), so im not sure how that would effect it if anything.

The replacement hose would need to be rated to carry fuel & should be the same size... could be that your fuel pump is struggling ? but I doubt it
Mate its not that hard to check over the carbs but as a back up get your LBS to have a look at them while they are off & give them a good clean then you can replace carefully... & while there you could get some proper hose

Yeah i shall replace the hose for sure!
Whats LBS?
And also, where is the fuel pump? The supply hose goes straight from the fuel shutoff valve (Which is connected to the fuel tank) to the carbs...

Local Bike Shop..... sounds like you have a gravity feed not fuel pump
later models ran a pump

Ah ok yeah, would be gravity feed. Maybe installing a pump would be an ideal mod.
I got the mechanic coming round next week.

Specwarop wrote:Ah ok yeah, would be gravity feed. Maybe installing a pump would be an ideal mod.
I got the mechanic coming round next week.

No mod.... would not need it mate... sounds like the mechanic having a look is the best bet... good luck

Thanks for your help!

Common problem with the ZZr250 is a kinked breather hose (runs under the tank). When you lift the tank it is on the left hand side, remove and refit tank checking this hose doesn't get squashed by the tank.

food for thought mike, but being a perimeter frame instead of a spine frame, i wouldn't have thought it that susceptible to having the breather hose blocked like that.

Well it turns out the reason it wouldn't start is because the bike is supposed to have a fuel pump, though it doesn't. Sounds like such an obvious problem...This is what the mechanic said anyways. And it turns out the brackets that hold the filter and pump are there. Just without anything on them.

Okay, well i got myself a secondhand fuel pump, hooked it all up and i don't think the pump is running. I put the pump directly to the battery, and the pump will click then stop. Not sure as to what that means.
Also when i flick the key to ON, the pump isn't getting power but when i press the START button the pump will then begin to get power. Again, not sure if thats normal.
Anyways im a bit confused and annoyed now. Maybe the relay is broken but also maybe the pump isn't working too. I would have thought the pump would run continuously when its hooked straight to the battery.

it should run continuously if it is hooked straight up to 12v. My old EFI Z1000 has a fuel pump that only kicks in when the motor is turning over. The later GpZ fuel pumps work as soon as the motor is running (ie after start button has been pushed) - the pump does not start running if you just turn the ignition to the 'On' position.

Not sure on the ZX9 pump, but if the one you are using only 'clicks' when you apply 12v across the terminals, it is stuffed as well.

2nd hand fuel pumps are always a lottery - check with your friendly local Bosch dealer (eg Dyno-Tune) for cars - you can buy genuine Bosch fuel pumps for about $300 - its way cheaper than stock Kawasaki parts......you will need to know the rated psi of the ZX9 pump - someone on here will know it I expect.....

Okay i disconnected the fuel hose from the inlet on the carbs, jumpered the pump straight to the battery and the fucker just runs on and on - so it works.
So something is making the pump stop when its connected to the carbs. Which is normal i assume if its stopping due to full floats or whatever. How does it pick this up, via pressure? Also i noticed in my pump to carb fuel hose there was a slight kink. I think that could have contributed largely to the problem.