KZ1000 carbs seeping petrol
Discussion
Hi Guys
I have a 1976 KZ1000 (Kawasaki) and it is suffering from petrol weeping out of the bottom of a couple of the carbs when not in use. It has been into my local shop (PDQ in Maidenhead) a couple of times and the guys have stripped, cleaned and refurbished the carbs, but the problem, although reduced considerably, persists. The shop says that if there is still leakage it must be the carb bodies that are the problem, and the only solution is new carb(s) which you can't really get.
It seems over 40 years that bad maintenance and servicing has done these carbs no favours, and modern replacement parts (when available, and mostly from China) are generally of inferior quality, so don't really do the job as well as the original parts.
Just curious, is this a common problem (generally, or with this bike) and has anyone else had this and found any solutions (except replacing the carbs)?
I have a 1976 KZ1000 (Kawasaki) and it is suffering from petrol weeping out of the bottom of a couple of the carbs when not in use. It has been into my local shop (PDQ in Maidenhead) a couple of times and the guys have stripped, cleaned and refurbished the carbs, but the problem, although reduced considerably, persists. The shop says that if there is still leakage it must be the carb bodies that are the problem, and the only solution is new carb(s) which you can't really get.
It seems over 40 years that bad maintenance and servicing has done these carbs no favours, and modern replacement parts (when available, and mostly from China) are generally of inferior quality, so don't really do the job as well as the original parts.
Just curious, is this a common problem (generally, or with this bike) and has anyone else had this and found any solutions (except replacing the carbs)?
These have a vacuum fuel tap?
Is the problem the tap leaking, as much as the carbs?
I don't know the carb in question, but generally, the fuel should be below the top of the float bowl, so the only leaks will the things like drain screws or whatever that go through the bottom of the float bowl.
If the float needles leak, then fuel will drain down the hose and overfill the bowl perhaps, whether or not the tap leaks.
My bikes with carbs have always been Italian or British or small bikes with simple taps, so you can turn the fuel off a little way from home and empty the carb.
Carbs can be very time consuming to get right,
Is the problem the tap leaking, as much as the carbs?
I don't know the carb in question, but generally, the fuel should be below the top of the float bowl, so the only leaks will the things like drain screws or whatever that go through the bottom of the float bowl.
If the float needles leak, then fuel will drain down the hose and overfill the bowl perhaps, whether or not the tap leaks.
My bikes with carbs have always been Italian or British or small bikes with simple taps, so you can turn the fuel off a little way from home and empty the carb.
Carbs can be very time consuming to get right,
These have a manual 'turn-off when not in use' fuel tap, which I do when it is parked up. The problem is there is still fuel in the pipes and carbs even if the fuel from the tank is not flowing, this causes the leakage when parked.
This has also been discussed elsewhere: https://kzrider.com/forum/3-carburetor/571279-1979...
This has also been discussed elsewhere: https://kzrider.com/forum/3-carburetor/571279-1979...
Edited by Blue One on Wednesday 16th October 11:32
As mentioned the fuel shouldn't get above the top of the bowl so there shouldn't be anywhere to leak from.
If I were you I'd take the bowl off yourself, slide the float pin out sideways and take the float out. Shake it to make sure it has no fuel in it indicating a leak.
Check the o ring on the float needles and maybe replace them anyway, along with the bowl o ring which shouldn't leak either. Dont overtighten the bowl as a stripped thread will definitely equal a leak! Once the bolt is home and snuggled up dont give it one for luck! Doing this will confirm that previous tech didnt overtighten it either.
If I were you I'd take the bowl off yourself, slide the float pin out sideways and take the float out. Shake it to make sure it has no fuel in it indicating a leak.
Check the o ring on the float needles and maybe replace them anyway, along with the bowl o ring which shouldn't leak either. Dont overtighten the bowl as a stripped thread will definitely equal a leak! Once the bolt is home and snuggled up dont give it one for luck! Doing this will confirm that previous tech didnt overtighten it either.
If you take the carb off and turn it upside down, the float valve should seal against you blowing into the fuel inlet.
If the very basics are not right, nothing else will be.
You need a needle valve seat in good nick.
You need a needle valve with ir's rubber (viton) tip[ in good nick.
The needle must be freely moving, with the float not jamming it, e.g. against the side of the hole where it runs.
The bits of the float that move the needle must be good nick and not jam the needle.
Ifthe float valve seat is removable, it must seal to the carb body nicely.
Then the height at which the float shuts off fuel must be 'near enough', definitely below the level where fuel leaks out anywhere.
Some bikes will leak a tiny amount if leaning a long way over on the side stand.
Leaks in the bowl gasket may be part of this.
The engines I have these days with float-bowl carbs are outboards, I try to run the carb dry. It means less petrol evaporating in the bowl, so less residue and less hassle.
TBH, if you're noticing fuel leaking faster than it evaporates from the warmth of the engine, the fuel tap needs to be checked.
If the very basics are not right, nothing else will be.
You need a needle valve seat in good nick.
You need a needle valve with ir's rubber (viton) tip[ in good nick.
The needle must be freely moving, with the float not jamming it, e.g. against the side of the hole where it runs.
The bits of the float that move the needle must be good nick and not jam the needle.
Ifthe float valve seat is removable, it must seal to the carb body nicely.
Then the height at which the float shuts off fuel must be 'near enough', definitely below the level where fuel leaks out anywhere.
Some bikes will leak a tiny amount if leaning a long way over on the side stand.
Leaks in the bowl gasket may be part of this.
The engines I have these days with float-bowl carbs are outboards, I try to run the carb dry. It means less petrol evaporating in the bowl, so less residue and less hassle.
TBH, if you're noticing fuel leaking faster than it evaporates from the warmth of the engine, the fuel tap needs to be checked.
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