Carbs still leaking !

[JimBoUK]

So, the carbs were leaking from the tops of the bowls on my Z1000A1.
I stripped them and gave them refurb using an ultrasonic cleaner.
I had a bit of grief getting the float heights right which is discussed in another thread
http://z1ownersclub.co.uk/phpBB3/viewtopic.php?f=4&t=45193
Finally sure I had the float heights right I fitted new bowl gaskets, then they went back on the bike and the carbs were balanced.
Today I went for the first ride since the carb rebuild. She ran like a dream and I did about 30 miles.
Got home to see the carbs slightly starting to leak again from the top of the bowls !!!!
I’m stumped now and gutted this is happening after all that work.
Should the new gaskets have stopped this if the fuel level did go a bit high ?
Any ideas to help will be greatly appreciated

[Ultim8pc]

I find that the cardboard gaskets need a little nip up again after initial installation. If this hasn't been done you can see some weeping, especially on the side stand.
I use the Keyster rebuild kits and they come with a rubberised bowl gasket which is far less troublesome than the card ones.
It is possible that some crap has got into the bowls and float valve, allowing more fuel to pass. (Old tanks etc). I recommend using some inline fuel filters.

[JimBoUK]

Thanks Ultim8pc
Won’t the fuel filter built into the tap be enough ?
There was no sign of petrol coming out of the overflow. Maybe the float valves are ok and it’s just a problem on the side stand. It does look like they are leaking from the left side.
It’s £100 for 4 keyster rebuild kits and I don’t need all the other parts.
Just ordered a sheet of Hexafluoropropylene 1mm high temp, fuel resistant rubber sheet. It was only £8.
Gonna try and cut new gaskets from this

[z1bman]

you must make sure the fuel tank is absolutely spotless inside by washing it out with a gallon of fuel shake it thoroughly & empty into a bowl & let it settle for a few minutes. do this several times until there are no contaminants in the fuel

[Charlie]

If the float needles are allowing fuel past, then fitting new gaskets will not fix the problem. It may however allow the fuel to flood into the engine via the inlet tracts and cause major issues. You need to discover WHY the float needles are not stopping the flow.

Pattern parts are nearly always problematic in my experience. I always source and fit proper Mikuni or Keihin (dependant on the carb). A bit more expensive yes, but guaranteed correct.

To answer your question about the tap filter being enough to stop crap coming through - no they are not.

Fit a good quality, preferable see-through line filter as well. You will be surprised just how much crud gets past the tap filter. It only needs a tiny amount to hold the float valves open, although fuel should come out the overflows rather than the float bowl gaskets - that's another issue you should address.

[zed1015]

If it's only on the side stand it's the bowl gaskets wicking due to the material they have used for them.
Try coating the gaskets with grease on install.
That usually seals the surface and does the trick.
If that fails it could be the bowls are warped due to overtightening and only nipping up on the corners.
If that's the case you need to lap them with wet'n'dry on a flat plate.
The plate needs a hole or slot in it for the overflow tube to hang through as it sticks up higher than the mating surface.

[JimBoUK]

I’m sure the carbs won’t overflow and it’s just a leak on the side stand where the level of fuel goes just over the top of the bowl on the left hand side.
The fact it’s happening on all 4 carbs also suggests it’s not a valve problem as it would more likely be just one or maybe two carbs.

Really good points zed1015
There is a chance the bowls have been overtightened by me I hate to say. They have Allen screws fitted which can go a lot tighter than the original Philips screws. I never considered I could warp the bowls. Doh !

So my plan is ....
Get some inline filters (got to be a good thing to do)
Make some rubber gaskets (I’ve already ordered a sheet of suitable rubber)
When I’m changing the gaskets (and not overtightening) check the bowl mating surface is flat and if not sort it.
I can do all this without taking the carbs off the bike again.

If after this the carbs were filling up due to dodgy valves I’d see fuel coming out of the overflows.

I’ll post back in a week of two with an update

Thanks

[Pigford]

Bloody tricky doing float bowl gaskets without removing the carb bank

[ADRIAN H]

Bloody tricky doing float bowl gaskets without removing the carb bank

That is true enough.

[FOZ1A]

No Disrespect intended, you need to send them to someone who knows what they are doing.

foz

[Ultim8pc]

If that fails it could be the bowls are warped due to overtightening and only nipping up on the corners.
If that's the case you need to lap them with wet'n'dry on a flat plate.

Or add another set of bowl gaskets.

[kev edwards]

If that fails it could be the bowls are warped due to overtightening and only nipping up on the corners.
If that's the case you need to lap them with wet'n'dry on a flat plate.

Or add another set of bowl gaskets.

more gaskets could make it worse, as you then have a larger cushion between both parts enabling you to clamp up even more, if it were mine i would pull the carbs and check the bowl faces for level as well as the carb bodies, i have seen bent corners on the bodies due to over enthusiastic tightening, and sometimes the gaskets just need to swell a little and then seal themselves.

[Ultim8pc]

more gaskets could make it worse, as you then have a larger cushion between both parts enabling you to clamp up even more, if it were mine i would pull the carbs and check the bowl faces for level as well as the carb bodies, i have seen bent corners on the bodies due to over enthusiastic tightening, and sometimes the gaskets just need to swell a little and then seal themselves.

I've used this method successfully with badly distorted carb bottoms. But the proper fix is as you described.

[DavidZ1R]

I had a problem on a set of carbs, I found the bowl gasket did swell too much, causing the float to catch and allowed to much fuel in, I trimmed them, all ok then.

[johny brando]

So, the carbs were leaking from the tops of the bowls on my Z1000A1.
I stripped them and gave them refurb using an ultrasonic cleaner.
I had a bit of grief getting the float heights right which is discussed in another thread
http://z1ownersclub.co.uk/phpBB3/viewtopic.php?f=4&t=45193
Finally sure I had the float heights right I fitted new bowl gaskets, then they went back on the bike and the carbs were balanced.
Today I went for the first ride since the carb rebuild. She ran like a dream and I did about 30 miles.
Got home to see the carbs slightly starting to leak again from the top of the bowls !!!!
I’m stumped now and gutted this is happening after all that work.
Should the new gaskets have stopped this if the fuel level did go a bit high ?
Any ideas to help will be greatly appreciated

Hi. If your carbs are 100% clean well then in my opinion probably you have one or more badly seating float needles ( =fuel level creeps up with tap turned on ) you can confirm this by using float drain point draining point & measuring each captured float fuel volume & checking again the volume 60 minutes later with the tap left ON during that 60 minutes period. If one leaks swap em around just to confirm this... then buy a new needle & seat if required. Either way always set your FUEL HEIGHT not your float height as that is used as merely a starting point / guesstimate. Cheers good luck & happy hunting.