Gas leaking after cleaning / bench sych carbs (another one)

[gdeangel]

I know there are other threads with same problem, but after reading them I still have a few questions hopefully folks here can help with.

First the problem - after cranking a few times, gas starts gushing out of the vent overflow tube. At least I think that's what it's called - the gas is gushing out the clear tub that I have connected from the upper crossover tube to under the bike. It also seems to be spraying back out into the air box.

My hose routing is (1) hose from L vac port to small port petcock (fuel pump), (2) hose from R vac port to emissions thingy, (3) fuel line from lower crossover tube up to large port on petcock (gas), and (4) line from upper crossover tube to under the bike... is that correct?

Now I was pretty careful to measure the float heights at exactly the point they make contact with spring on the float needles. I set them at 17.7 mm. Originally it was around 16.5 on one side, and something like 23 on the other, which side had no gas in the bowl when I started the job and a "stuck" spring on the float needle... The rubber on the tips of the float needles looked fine.

Over at Kawasakimotorcycle.org, I came across this:

If fuel is coming out of the overflow hoses than either the float is unable to stop the fuel flow due to debris as described by the OP or the float level is incorrect and allowing the bowl to overfill. A third possibility is a bad float, but that is rare

Focusing in on the float level, when I pulled the carb, the float needles were in vastly different states of "varnish", and the float heights were also set very differently. But the bike ran, and I never saw a drop of gas overflow from the carbs. It just was next-to impossible to start when not run for a few days without a blast of carb cleaner to the air intake. Is it possible this setup of different L and R float heights was deliberate? I think I may end up replacing the float needles... found some online that are selling for about $10 new.

I also did clean the tank, which was a long and sordid affair, but in the end it might have still been possible that some tiny rust particle got through the petcock screens and is compromising the needle seat.  And as far as the floats, I noticed when I first disassembled the carb that one looked like it had some gas in it, but I figured since the bike wasn't flooding then, that whatever the situation, it was a slow, minor issue that didn't affect the pressure on the needle enough to mess things up - plus new floats aren't quite as easy to come by as float needles!


So now the practical question - how the heck to get the 4 bowl screws off without pulling the carb again!?

[Blaine]

Hard to do.But it can be accomplished with a small right angled driver.Be careful not to strip the screws. :0

[gdeangel]

Yup, that did the trick. Had two of three... crystal of gunk in the needle seat, floats not shutting off (too low), but fortunately didn't see any cracks or gas inside the floats.

Used a cheater method of setting the float height with the bowls off... had my wife pour gas into a funnel , rags under the carbs, and raise the float by hand until no more gas dripping. Hold with one hand, then measure with calliper. Remove float and bend tab accordingly with a rough eye on where the float's "water line" is vs. the jet pickup ports.

I had it bench set at 17mm +/- and the bike basically flooded out the air intakes and vent tube after a couple cranks. Using the above method, I came up with about 22 +/- on each side. At that setting, bike was able to be started without flooding, BUT still floods when left sitting around. Normally the petcock would seal with the bike shut down so this wouldn't be an issue BUT I added a fuel filter and the tablespoon or so of gas that's sloshing around in there when I shut down is making it's way into the carb as the bike sits. Yes, it's still a float needle issue, but if the setup was a good petcock seal and no fuel filter then the issue would be undetectable.

I may mess around some more and try to adjust tabs on float, but reality is that the springs in the float needles, although they still actuate, are not applying enough pressure to seat the needle at the 17mm-19mm spec height. Long term solution = replace float needles. Found some on eBay that might work. Also have to check out the local carb place.

[gdeangel]

In case anyone in future is referencing this thread for their own job, after replacing bother float needles with new ones from rebuild kit, bike was still flooding out the vent tube at 17mm, but problem seems to be corrected at 19mm, which is still within spec. Probably floats not exactly leaking, but they may have absorbed fuel vapours over the years changing their buoyancy.

Nice thing with the kit, got new set of bowl gaskets, which if your careful, can seal the bowls with just the two outside screws, meaning a lot easier job getting them on and off for adjustment... although still a pain.

One thing to note, with the vent tube routed under the bike, the way it's supposed to be, gas was leaking out in really strange places, near the back of the exhaust mounting bolts. Even worse, I was getting what looked like oil spray from the left side of the engine. Turned out it was gas running down the frame, and with it a lot of road gunk & tar that made it look like oil.

[jez]

Have been having the same trouble. I have had the carbs apart several times and replaced float valves and polished seats and set float hights but it still leaks out pod filters and overflow pipe. I, m going to try adjusting float level to 19mm as you suggested and try that. Also having starting problems. Bought the "project" as 5 boxes of bits and beginning to wonder if that's why they sold it. is yours all running fine now? 

[Blaine]

Dec 23, 2016 10:28:47 GMT -6 jez said:

Have been having the same trouble. I have had the carbs apart several times and replaced float valves and polished seats and set float hights but it still leaks out pod filters and overflow pipe. I, m going to try adjusting float level to 19mm as you suggested and try that. Also having starting problems. Bought the "project" as 5 boxes of bits and beginning to wonder if that's why they sold it. is yours all running fine now? 

You have the fuel hose on the Proper 'T"?......The lower one.....The upper "T" is a vent & remains open.

[jez]

Have adjusted float by 1mm at a time, trying each time. Have finally found when set to 20mm that the engine starts, runs and revs as it should. Have come to the conclusion that the petrol was over filling causing petrol to leak into the carbs which was causing the engine to rev high until it got so rich that it flooded. All good now, now I can move on.