Carb Drain Bolt Leak

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IMG_6069ss.jpg

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

Could be. I bought those from Bob Raber or Phil Radford. Not sure about what they were made for. I wanted more fuel around the mains, and they work for that.

I didn't cut a taper on the bowl mating surface. These old Amal 930's (circa 1970's) are really soft and apparently the hard jet cover sealed by just tightening them up when I was using the carburetors. Not about to verify if they actually seal now though. Those old things are working perfectly in a box. They have 220 mains in them, but I think I polished the needles, so that may have had something to do with the smaller mains. They worked more or less when the motor was stock. I replaced them with Mikuni 34mm carbonators during a teardown rebuild pre-midlife crisis tuning frenzy.
 

Yakatak

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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.
Can you provide info on what size Dowtys you used?
 

elefantrider

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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.
They need to be tighter than just compressing the lock washer or will back out. Have had it happen to me so I am less worried about warping the bowl than being stranded. The philips head bowl screws will not allow you to get them tight enough to prevent backing out, in my opinion. Flat head or hex head bowl screws are better.
 
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I gave up trying to stop my plugs from weeping so I sourced a pair of the old style float bowls without a drain plug. Problem solved!
 
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marshg246

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They need to be tighter than just compressing the lock washer or will back out. Have had it happen to me so I am less worried about warping the bowl than being stranded. The philips head bowl screws will not allow you to get them tight enough to prevent backing out, in my opinion. Flat head or hex head bowl screws are better.
Weird. Never had any come loose in 52 years and I've never had a customer complaint either.
 

Fast Eddie

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Weird. Never had any come loose in 52 years and I've never had a customer complaint either.
Same here. Hardly ever bother changing the gasket either !

I suspect it sometimes gets an unfair bad rep. Being at the very bottom, ANY minor leak will show itself there.
 

elefantrider

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It can happen. I know of another instance of it happening on another persons bike.

In my case, both screws dropped , the bowl came off and it lost the float axle. We made a new axle out of a tin can that we found on the side of the road, and used a screw from the other bowl to hold it up. Rode it that way to get back home.

I still have the pics which my friend, a former Manx racer, took.

For this reason, I am not a huge fan of the drain plug bowls either.
Good in principle, bad in practice unless you can safety wire them?
 
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Tornado

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There was an aussie posting on ebay for a kit to change the bowl to attach to carb via the main jet brass. Bowl screws to be threaded in from above the body flange, only serving a location posts for the bowl. Quite clever really, no more issues with over tightening at the flanges. Dropping whole bowl then becomes a one easy to reach fastener affair.
 

johnm

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Looks like a Monobloc main jet cover. Maybe you turned a taper on the bowl, to match it.
Yes it is and they come with a taper that seals without the need of a gasket. I used them for many years on a 500 twin race bike and they worked perfectly
 
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I fitted a pair of plated brass drain plugs with Dowty washers and there as dry as a bone.
To avoid the brown smelly lacquer coating & blocking the jets, i remove the drain plugs if i know the bike will be standing more than a week. This process has been carried out on numerous occasions over the last 14 month using the same dowty washers & i have no leaks
 

maylar

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The brass drain plugs can be had from any of the Brit parts suppliers. I bought a box of assorted sizes of Dowty washers from Amazon.
 

river700

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miracle micro-ratchet and hex bit,
Any more info or pic. What brand of ratchet?
Just got 73 850 with small rt carb gas leak. Replaced gaskets & put in stay up floats. Still leaked= traced to fuel leaking out around base of tickler when engine running. Is that a bad o-ring? Can't find a diagram of it.
 

marshg246

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Any more info or pic. What brand of ratchet?
Just got 73 850 with small rt carb gas leak. Replaced gaskets & put in stay up floats. Still leaked= traced to fuel leaking out around base of tickler when engine running. Is that a bad o-ring? Can't find a diagram of it.
No, that's wrong fuel (float) height or bad float needle - you're continually flooding.
 

Tornado

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Any more info or pic. What brand of ratchet?
Just got 73 850 with small rt carb gas leak. Replaced gaskets & put in stay up floats. Still leaked= traced to fuel leaking out around base of tickler when engine running. Is that a bad o-ring? Can't find a diagram of it.
ae235.jpeg


Got mine at local automotive store (Canadian Tire) but can be had amazon etc.

Your issue could be bad float needle. New types are alloy with viton tip. Good idea to polish the sealing seat surface with Autosol or similar on a Q-tip and running it in a drill.

Could also be incorrect float height. New stays ups have a different recommended setting than originals. See Bushmans Guide for Amal carbs under the technical info sticky thread on this forum.
 
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" New stays ups have a different recommended setting than originals."

Good upgrade for the Premiers is replacing the stay-up floats with the originals! :rolleyes:
 

Fast Eddie

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" New stays ups have a different recommended setting than originals."

Good upgrade for the Premiers is replacing the stay-up floats with the originals! :rolleyes:
Several folk have reported exactly that !

There have also been reports of burrs on the float tang preventing the needle from seating correctly. I looked at mine and they were indeed quite rough stamped parts (considering their application). Dressing with fine files and emery definitely advised.
Or replacement with plastic !
 
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