Topic: Leaking float bowl at gasket, could this mean bad float cutoff?

[evanphi]

Also there is no top plate on the Airbox (this is long gone) the filter is jammed in with a rubber stop to make sure it's not leaking in the airbox itself.

Pics of this?

[harisuluv]

Also there is no top plate on the Airbox (this is long gone) the filter is jammed in with a rubber stop to make sure it's not leaking in the airbox itself.

Pics of this?

Yeah I kind of gave up on trying to help, I can't even follow what's going on.  pictures, seriously.

[scrichton]

I can't get to the bike today, but it's easy to describe.

Imagine looking down from above into the airbox. There is a standard filter sitting in there. Then at the non-manifold side I have jammed a bit of rubber in there to ensure the filter is 100% sealed against the mouth of the inlet. As in sealed tight in there, so it's not passing any unfiltered air.

Other than that the air-box is standard, has the oil breathers connected etc.. but no top plate.

The rest of the bike is standard, apart from the JAMA 4->1 standard jetting, standard bore size and all compression checked. Floats at 12.5mm. No inline filter. Timing is statically timed as per the workshop manuals, checked 3 times against both clymer and the honda one, as are the gaps. Needles are the normal clip heights for a 77 carb (although it was registered 78 it has the 77 type kehlin variant)

[lucky]

I can't get to the bike today, but it's easy to describe.

Imagine looking down from above into the airbox. There is a standard filter sitting in there. Then at the non-manifold side I have jammed a bit of rubber in there to ensure the filter is 100% sealed against the mouth of the inlet. As in sealed tight in there, so it's not passing any unfiltered air.

Other than that the air-box is standard, has the oil breathers connected etc.. but no top plate.

The rest of the bike is standard, apart from the JAMA 4->1 standard jetting, standard bore size and all compression checked. Floats at 12.5mm. No inline filter. Timing is statically timed as per the workshop manuals, checked 3 times against both clymer and the honda one, as are the gaps. Needles are the normal clip heights for a 77 carb (although it was registered 78 it has the 77 type kehlin variant)

Does it have a accelerator pump on carb#2?
 Also did you remove all 4 mixture screws and check the O rings?
Many times the O rings are all buggered up.
There should be a spring,washer and O ring. The O ring goes in first, then the washer, then the spring, and finally the needle.

[lucky]

Also there is no top plate on the Airbox (this is long gone) the filter is jammed in with a rubber stop to make sure it's not leaking in the airbox itself.

Pics of this?

Yeah I kind of gave up on trying to help, I can't even follow what's going on.  pictures, seriously.

His process is not in any order. Hard to help.

[jonda500]

550's don't have throttle pumps.

the overflow tubes inside the float bowls protrude higher than the top of the bowl - if the needle and seat is leaking or the float mechanism is sticking the bowl will over fill and flow out the overflow pipe.. UNLESS your float bowl gasket is leaking in which case the fuel will run down the outside of the float bowl and the fuel level wont get high enough to run out the overflow tube.

Sorry I know this doesn't really help, but I really hope you can find some one that can help you with your problem so you don't have to give up on this bike! John

[scrichton]

yes there is an accelerator pump as far as I can remember.

Here's the full rundown in order


The mix screws all were cleaned through the old O Rings removed and the screw was replaced washer->spring->screw.

The top gaskets were replaced on the carbs.

The float bowls were cleaned very thoroughly and blown through. Then new O-rings on the drain screws.

The floats had the level set to 12.5mm

Needles were set to the correct clip as per the kehlin workshop manual specs.

Jets were cleaned and emulsion tubes were removed (with main jets out) and cleaned checking all side vent holes down the length of them.

The inlet's to the cylinder head had new gaskets and torqued to spec.

All inlet boots were checked for visible cracks and perishing (I've had old Porsches which used sealed vacuum injection systems, so got very used to finding air leaks)

The fuel line from the petcock was replaced with clear line to check fuel feed + new filter. (tank is now full of new petrol at this time)

Once this was done the carbs were replaced and mix screws set to 1.5 turn and idle screw adjusted until an idle of 1.5 k was solidly there, with the mix screws adjusted accordingly ensuring all adjustments were equal.

Idle had a slight wavering, but due to the clutch basket noise I know I need to sync the carbs ( sync gauge is sitting on the tool table awaiting a running bike)

This was then attempted to be driven. Under 5k it would run lumpily. Under idle and revving with no load there seemed to be few issues. Under load the bike hesitated, above 5k the bike would simply not rev.

After this run I did a plug chop as new plugs were put in before this process (timing chain was adjusted and new exhaust gaskets were installed before the carbs were removed)

Plug chop showed a wet plug 1.

I swapped the leads between 1&4 then let the bike run for a while. which reduced this.  Therefore looking at either a lead / cap /coil issue (sealed leads into the coil). The coil was replaced with a new part as were the plug caps, using NGK 5k caps. This restored sparks evenly, but the same hesitation remained.

I then replaced and set both the points and the condensers, plus cleaned and fully lubricated and tested the advance plate. Which was smooth with no notches etc ..

This Saturday:

I once again removed the carbs. Checked the inlet to Cylinder head manifold tubes, in case there was a leak here. They are correctly torqued with the new gaskets in.

The carbs then had the float bowls off again. There was no signs of stuck floats, every ran free (taps were done on the bowls as they had filled). I then re-checked the float heights at the tips of the floats furthest from the fulcrum at 12.5mm again. I then removed each main jet and checked once more the emulsion tube and the jet. Using wire to clean both the main and slow jets with cleaner and re-assembled.

Once all was tight, manifold boots checked, air filter (sealed with a rubber press as described to push it to the inlet face) I started the bike, set the idle screw and attempted a ride. Once again 4-5k and above no power, much hesitation. Managed all of 500 yards maybe. (choke was off as engine had been warmed)

From here I returned and then removed the inline fuel filter and replaced the line with a single piece of pipe doubting the fuel filter's flow. I also checked the floats were filling and did the required tapping.  Checking the exhaust manifolds #2 was colder #4/#3 was hot #1 was in-between.

Going back out the fuel filter had been a cause of some leaning. So now the bike would rev to 7k under load before missing. Managed once round the block (forgetting how bad the brakes are when coming off a modern bmw earlier in the day!)

I then checked the exhaust temps again with the engine hot at the base of the branches #1 hot #2 cold (not freezing) #3 hot #4 hot.

After all this Daylight was fading and I was so disheartened this is where we are now.

(Previous to all of this the head was skimmed, new valve guides were done on all exhaust and inlets, new rings etc .. Plus valve clearances were set 30 miles before any of this)

Sorry for no pictures, but the garage is a bit dark and I tried to make as much progress in work as I could whilst I could use the short daylight here in winter.

[scrichton]

I may be mistaken on the pump, I was looking at the wrong nozzle on a diagram, to see what they look like.

Either way if there was a passageway it was cleaned then cleaned again!