Carb Drain Bolt Leak

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Tornado

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Any tips to ensure the float bowl drain cap/bolt on new Amal Premiers won't leak? I had the drains off both new carb to perform fuel level checks with home made old plastic drain bolt, spigot and some clear hose. Next day once fired up I found one side drain dripping. Best I could tell it was from the drain, not fuel input banjo or bowl gasket. Gave it a quick snug up but didn't fully stop drops appearing.
Gasket looks fine, not distorted. Using thread sealant doesn't seem wise here.
 
Yes, it shouldn’t need thread sealant. The thread isn’t sealing anything, it’s the gasket face doin’ the sealin’. Shouldn’t need a lot of torque either. These normally seal easily, so I’d be looking for a damaged face or gasket, or dirt.

Also, as the drain is in the very bottom of the carb, remember that any small leak anywhere is gonna dribble down to the drain bung.
 
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I automatically replace the fiber washers when removing fuel banjo or drain plugs .... old habits from being on the spanners like always replacing split pins & one use only nyloc nuts
 
Not sure of the coin in CA, but I only use a US quarter coin to tighten/loosen them. The gasket is not hard to crack. I would think it more likely that the bowl is leaking at the body. You probably already know, but on Amal carbs you should only tighten the screws until the lock washers are flat - it's real easy to distort the bowl and make them leak by over tightening.
 
The new green washers seal better but don't seem to last very many cycles. The old red ones
are harder and last longer but don't seal as well. I like the plastic drain bungs but they don't
work so well when you bike is on fire.
 
The new green washers seal better but don't seem to last very many cycles. The old red ones
are harder and last longer but don't seal as well. I like the plastic drain bungs but they don't
work so well when you bike is on fire.
I have looked at sourcing some Dowty seals, but to date cant get a good enough size match... i switched to steel bungs to get away from those horrid plastic items
 
Thx. The new carbs have steel drain caps with red , hard gaskets. Will have that carb off bike today to have another go at checking/clearing the pilot jet orifices. Will do some tests on the bowl drain.
 
Agree about the green gaskets being problematic; I've had them split/leak several times on the drain plug. :(
 
I just went out and looked at my old set of Amal 930's and my drain plug has a tapered seat that seals against the bowl. Either that or the gaskets rotted and disappeared entirely. The carburetors have been in a box for at least 28 years. The drain plugs tightened up with a wrench. I may have gone to this style drain plug to get rid of the gasket issue. I know I did it for extra space under the mains.

Carb Drain Bolt Leak
 
Went thru the carb, seemed to have a dribbly tiny pilot by-pass orifice again. Removed pilot and air screws to make a straight shot through the passage to help wash out any offending debris. Again hit the orifice with very fine wire. Seems to have cleared, getting good spray out once again.

Used another gasket on the drain cap (only had a spare green fibre type). Will see how it handles it.
Getting pretty good with pulling carbs off now, with my little miracle micro-ratchet and hex bit, I can get to those manifold bolts pretty well and drop the carb, then access top screws to lower whole body away from the throttle slide/needle. All done without pulling tank or even seat off.

Test run up tomorrow...
 
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Not sure of the coin in CA, but I only use a US quarter coin to tighten/loosen them. The gasket is not hard to crack. I would think it more likely that the bowl is leaking at the body. You probably already know, but on Amal carbs you should only tighten the screws until the lock washers are flat - it's real easy to distort the bowl and make them leak by over tightening.
The end of the inspection cap tool is a perfect fit.

 
The sealing ring area is maybe 1 mm (0.040") wide at the ID, I gave the bowl surface a light lap.
You can see the ring, most of the sealing surface is beyond the bowl so might be a little finicky.

Carb Drain Bolt Leak
 
The end of the inspection cap tool is a perfect fit.

I use a coin because it's hard to over-tighten with a coin and there's not a lot of room under the carbs on most bikes.
 
I can say that last 30 yrs my VM34 has not dripped a drop , the drain screw is metal on metal ( way it came) certainly wondered if an o-ring was missing but went with it way it was …. quality seems hard to find even with new Amals …. good luck ! …. I mean that as I much prefer the look of the twin Amal setup , just not living with them …..
 
Any tips to ensure the float bowl drain cap/bolt on new Amal Premiers won't leak? I had the drains off both new carb to perform fuel level checks with home made old plastic drain bolt, spigot and some clear hose. Next day once fired up I found one side drain dripping. Best I could tell it was from the drain, not fuel input banjo or bowl gasket. Gave it a quick snug up but didn't fully stop drops appearing.
Gasket looks fine, not distorted. Using thread sealant doesn't seem wise here.
When they started spoiling good petrol with ethanol, I fitted Viton Dowty washers to the later metal drain plugs, they work fine and you can drain the carbs as often as you like and re-use the washers Stato seals would also work.
 
Seems cured now. Went through the drippy side drain and fuel port seal/gasket...re-fitting and still dripping. Took whole bowl off and tried filling it with brake cleaner while watching the fittings...no leaks. Tried a fresh bit of hose to go between the two carbs, and seems to have solved it. The older hose there was only a year old at most...proper ethanol-rated 1/4 fuel line....so maybe just a bit too hardened for this size hose barbs (i run the spring type hose clips there for easier access than jubilee clamps...might need to change to those..).
 
Extraneous babble: I use 5/16"Continental 50psi rated black fuel/emissions hose and FI style hose clamps on the Norton. Works with ethanol. Not as pretty as the old school clear stuff and jubilee clamps, but I can loosen the clamps, remove the fuel hoses from barb fittings, slide the hoses back on, and tighten up the clamps with zero leaks. The FI style clamps seal better and don't mess up the hose unless over tightened. They don't require a lot of tightening on zero pressure lines. Plus they are less expensive than Jubilee clamps. The negative is that you need to have room for the tightening mechanism and select the right size for the hose being used. FI clamp ranges are not as forgiving as worm drive clamps on sizing.
 
I just went out and looked at my old set of Amal 930's and my drain plug has a tapered seat that seals against the bowl. Either that or the gaskets rotted and disappeared entirely. The carburetors have been in a box for at least 28 years. The drain plugs tightened up with a wrench. I may have gone to this style drain plug to get rid of the gasket issue. I know I did it for extra space under the mains.

Carb Drain Bolt Leak

Looks like a Monobloc main jet cover. Maybe you turned a taper on the bowl, to match it.
 
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