new problem today - ??? - leaking float needle, hydraulic lock (left carb only) - possible?

was getting ready for a ride today, and noticed the LH manifold gasket appeared to be wet - not leaking gas, just wet. i'm assuming it's from fuel - thought it was odd, but really didn't give it much thought (BTW, wettness not caused from tickling the carbs). anyway, got ready to start the bike with my new alton starter - hit the start button, and nothing - starter engaged, but seemed the engine was hitting a brick wall. hit the starter button (briefly) several times - same thing. got off the bike, and tried the kick start - seemed I was on the compression stroke, but appeared to bleed off ok. seemed to turn over with the kick start OK - was getting a couple ignition "pops", but no start. so I go back on the starter, and the engine spun normally, and started immediately. went out for a 40 mile ride - stopped and started a couple times without issue - engine spun fine - pretty much normal.

I checked the float level on the left carb several weeks ago when I noticed fuel on the rubber boot connecting the carb to the air cleaner assembly. fairly sure the float level is correct, so i'm wondering if the (float) needle valve is doing it's job? the bike sits with the fuel petcock off, but not sure the thing is not seeping fuel past the "off" position.

so, my question - my hydraulic lock theory worth a look, or am I out in left field and should I be looking elsewhere? second question, is the float, needle valve seat in the float bowl serviceable, OR is the float bowl itself a replacement item? been kind of having this "on and off" problem since I got the bike running - even before the e-start mod. wrote it off to compression and nature of the beast, but now i'm wondering if I haven't seeping fuel issue all along, OR is this another one of joe's over-thinking things, again. i'm thinking it would take a fair amount of fuel to cause hydraulic lock. not sure there's enough residual standing fuel to cause this problem. TIA for any comments.

Are you turning off the fuel taps when you leave the bike? Do they leak?

batrider said:

Are you turning off the fuel taps when you leave the bike? Do they leak?

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I do turn off the taps, but suspect the LH petcock does "seep" a bit. even with the taps in the off position, there is a "standing" amount of fuel in the lines, downstream of the petcock valve and above the float level. i'm wondering if there's sufficient gas there to cause the problem. even the reserve fuel line would add to the problem - if that is the problem. kind of puzzled right now.

I'd take both bowls off.
Inspect to see if the float pivot pin is riding deep into it's groove. I very gently peen each side of the slot to make sure of that.
Also how old are the float needles ? I'd replace both with the new aluminum body type. Rubber doesn't last forever in fuel. Reassemble with new bowl gaskets. The floats themselves can be replaced if old too , the left may be old and taking in fuel ? Inspect.

If you believe that you had a hydraulic lock, you should change the oil , as the gas if it was in the cylinder(s) will seep past the rings into the oil.

Torontonian said:

I'd take both bowls off.
Inspect to see if the float pivot pin is riding deep into it's groove. I very gently peen each side of the slot to make sure of that.
Also how old are the float needles ? I'd replace both with the new aluminum body type. Rubber doesn't last forever in fuel. Reassemble with new bowl gaskets. The floats themselves can be replaced if old too , the left may be old and taking in fuel ? Inspect.

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fairly confident that both pivot pins are properly set. both needles are new aluminum types as well as new e-proof floats. probably inspect everything and I may replace the needles and switch float bowls and see if the "wet gasket" problem migrates to the right.

Leaking float needles are one of the unnecessary problems that people who believe that the must get the fuel height as high as possible, tend to have. If your fuel level is a little bit lower than the maximum possible height, you avoid spillage due to poor seating pressure on the needle, and leakage from vibration. The idle air screw is used to adjust for the fuel height, so no reason to give yourself a possible headache by risking setting the fuel height too high...

o0norton0o said:

Leaking float needles are one of the unnecessary problems that people who believe that the must get the fuel height as high as possible, tend to have. If your fuel level is a little bit lower than the maximum possible height, you avoid spillage due to poor seating pressure on the needle, and leakage from vibration. The idle air screw is used to adjust for the fuel height, so no reason to give yourself a possible headache by risking setting the fuel height too high...

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fairly sure both float levels are set below the edge of the float bowl. issue seems to be with the LH carb only - that's why I suspect the needle valve may not be properly seating. it may be a hit or miss thing since it doesn't seem to happen all the time. I seem to recall, that every once in awhile, the observed fuel level in my (clear) fuel lines (with the petcocks off) does drop over time while if bike sits for days. need to keep track of that in relation to the "lock" issue. never put two and two together or gave it any thought. probably a lot of upfront detective work I can do to sort through this. puzzled....

Well, of course it could be something other than what I proposed. I'm just saying that many people seem to think their is some greater purpose to having the highest possible fuel height. I don't think it makes any difference if the fuel height is an 1/8th" lower, except that you know fuel won't leak from vibration... and the idle air screw will adjust for the lower height so long as it's within reason.

WTBS, maybe your float is hanging up ever so slightly on the gasket... that does happen... giving you slow leak of fuel. If your intake valve just happened to be open on that side, you could get that hydraulic lock you spoke of, and as Dan said, Check your oil for fuel contamination as a diagnostic check.

I for got to turn off my fuel tap one time and next day I started my bike and all of a sudden my breather hose that I run into a catch bottle filled with oil and a strong smell of fuel, turn out one of my float needle stuck open, my bottom end was filled with oil/fuel, changed the oil and removed the float bowl and found a bit of gasket had caused the float needle to stay open, kept a look out for sign of fuel leaking down after refitting, it never did that again was just a one off thing that happened.

Ashley

Disconnect the fuel line at the carb and run it into a can. Check it every so often to see if it's leaking. If so replace the petcocks. I'd do both and I really like the BAP style. I wouldn't rely on float needle.

htown16 said:

Disconnect the fuel line at the carb and run it into a can. Check it every so often to see if it's leaking. If so replace the petcocks. I'd do both and I really like the BAP style. I wouldn't rely on float needle.

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I have a set of new BAP's - just waiting of a couple parts for some maintenance items on the bike where I can pull the tank. plan on replacing the existing petcocks at that time. the one's I seem to have look to be a standard replacement for the commando, but IMO, they leave a lot to be desired. even if the petcocks are not leaking, there's a standing amount of fuel, below the petcock's actual shutoff valve and above the level of the float. if the needle is leaking the fuel will seek a level somewhere below carb throat and/or the inlet port of the engine. the excess fuel has to go somewhere.

lf you are worried about fuel in the cylinder try pulling the plugs first and then cranking it over.

I recently had one of those fairly new Al needle fail me and had to change it out. It sure would be nice if Amal were to produce clear bowls.

“so, my question - my hydraulic lock theory worth a look, or am I out in left field”

No.
Yes.
A cylinder full of gas would still be evident. And would not have bled down.

concours said:

“so, my question - my hydraulic lock theory worth a look, or am I out in left field”

No.
Yes.
A cylinder full of gas would still be evident. And would not have bled down.

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OK, but based on my original post, what do you think is going on? ...from my original post -- "...and should I be looking elsewhere?"

The new black floats do seem more buoyant and ride very high.
perhaps your float is high. My new ones were so high that the needle could not fully close.
I know - just a guess! But easy to test.
I would set the float bowl up on the bench with a fuel feed, put the gasket in position and a couple of weights to hold the gasket and pin in place. I used an old plastic bowl bung that I drilled out and screwed in an old drilled out grease nipple as a hose connector.
You can then slowly fill the bowl and see the fuel level when the Needle closes. Closest thing you can get to having a glass bowl.When I did this I found that the floats as supplied were way to high. I ended up bending the tangs so that the float was level with the bowl when closed.
Also the float needle doesn’t always slide very well in the groove of the float. Mine had quite rough metal edges that were improved by sanding them smooth

joe czech said:

OK, but based on my original post, what do you think is going on? ...from my original post -- "...and should I be looking elsewhere?"

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No, you didn’t hydraulic lock the engine with gas, and Yes, look elsewhere (from that theory).
Put new petcocks on it and make sure the needle seat is working.
I’ve dozens of those instances when the kicker stops, with my 240 lbs lock kneed coming down on it. (Not just Norton)

concours said:

Put new petcocks on it and make sure the needle seat is working.

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that's the plan, stan -

concours said:

No, you didn’t hydraulic lock the engine with gas, and Yes, look elsewhere (from that theory).
Put new petcocks on it and make sure the needle seat is working.
I’ve dozens of those instances when the kicker stops, with my 240 lbs lock kneed coming down on it. (Not just Norton)

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OK here's one, I have a 650 jap 4 that has vacuum petcocks, I forgot to close the tap off and came out the same afternoon to start the bike up on the button one sunny day, didn't notice the smell of gas, just heard a slight crunch when pressed the starter button, this was the sound of a Morse chain breaking. Worse, the same chain also drives the piggyback alternator- so no charge to the battery. Even worse, its a chain that is unique to that one particular model and unobtainable. The air was a bit blue that afternoon at my house.