Amal carbs

nopdog · Jul 2, 2023

Need some advice.
Put some new amals on my 71 Commando about 12 months ago and they have both been running fine until recently when the right slide started sticking at half throttle and up.
I’ve been running about 2mil hard gaskets between carb body and manifolds and hard gaskets between manifolds and head. Is this ok?
I’ve also been using locktight in the screws and nuts. What torque is recommended for the nuts carb to manifold and manifold to head.

I’ve just taken the carb off again (I’m getting pretty good at it) and the slide is a little tight in the carb barrel from about halfway up. Is it ok to lightly sand the barrel with wet n dry till I get free movement?
Thought I would ask before I do something I can’t undo.
Thanks
Simon
I should also say that I’ve only been doing the nuts up on the carb to manifold tight when it just bites and then about half a turn.

texasSlick · Jul 3, 2023

Amal carbs bodies can easily be mashed out of round. I have heard of someone squeezing them back to round, but that seems like a risky endeavor to me.

A light sanding would be a nothing to lose endeavor, particularly if you study where the binding is occurring.

Carb bolts/nuts do not need be over tight, snug is enough. I would guess 12 ft lbs. I do not think loctite is justified.

Hope you can work it out.

Slick

Mike40M · Jul 3, 2023

https://amalcarb.co.uk/technical/installing-amal-carburetters

Triton Thrasher · Jul 3, 2023

It doesn’t have a fibreglass petrol tank, does it?

nopdog · Jul 3, 2023

Triton Thrasher said:
It doesn’t have a fibreglass petrol tank, does it?

No

kommando · Jul 3, 2023

I use a nyloc nut and a spring washer, as soon as the spring washer is flat I stop tightening the nut and never had a body distort or a nut come undone.

Cuppy · Jul 3, 2023

Triton Thrasher said:
It doesn’t have a fibreglass petrol tank, does it?

Just curious what effect that would have on a sticking slide?

YING · Jul 3, 2023

Nopdog,
Are you sure that the cables aren’t your problem? If not,can you see where the slide is sticking?
Mike

baz · Jul 3, 2023

Cuppy said:
Just curious what effect that would have on a sticking slide?

The fiberglass melts and can leave a sticky deposit on the slide
I'd imagine tank sealent could do the same

L.A.B. · Jul 3, 2023

Cuppy said:
Just curious what effect that would have on a sticking slide?

figerglas tank resin caming out in carb

long story short, had a planned ride with the new emgo tank, and had it all mounted but the Comnoz head steady mount was banging on the tank underside and there was no time to resolve it so i remounted the dunstall fiberglas tank, by the time i had ridden 100 mi the throttle was hanging up, and...

www.accessnorton.com

baz · Jul 3, 2023

You can clean the slide and colour in with a marker pen to show where the high spots are and dress them down
Not ideal and you shouldn't have to do it on carbs of that age

EstuaryBoy · Jul 3, 2023

I have in the past (before I knew only half of everything!) used solvol to 'lap in' a sticky slide. Time consuming, but less aggressive than wet and dry.

concours · Jul 3, 2023

I've watched Dude Wheeler put them in a bench vise, and very gently squeeze them back into shape. Slide moves free, no metal removed.

robs ss · Jul 3, 2023

texasSlick said:
Amal carbs bodies can easily be mashed out of round. I have heard of someone squeezing them back to round, but that seems like a risky endeavor to me.

A light sanding would be a nothing to lose endeavor, particularly if you study where the binding is occurring.

Carb bolts/nuts do not need be over tight, snug is enough. I would guess 12 ft lbs. I do not think loctite is justified.

Hope you can work it out.

Slick

On my 650ss the slides were loose and wobbly.
I bought new Burlens anodised slides and they wouldn't fit.
Measured the bores and they weren't round.
Gently squeezed the carb bodies in a vise (padded with balsa wood) and eventually got them round.
Put the new slides in and - viola - they are like new.

Put it down to a previous owner being a bit too keen in tightening carbs
Cheers

marshg246 · Jul 3, 2023

nopdog said:
Need some advice.
Put some new amals on my 71 Commando about 12 months ago and they have both been running fine until recently when the right slide started sticking at half throttle and up.
I’ve been running about 2mil hard gaskets between carb body and manifolds and hard gaskets between manifolds and head. Is this ok?
I’ve also been using locktight in the screws and nuts. What torque is recommended for the nuts carb to manifold and manifold to head.

I’ve just taken the carb off again (I’m getting pretty good at it) and the slide is a little tight in the carb barrel from about halfway up. Is it ok to lightly sand the barrel with wet n dry till I get free movement?
Thought I would ask before I do something I can’t undo.
Thanks
Simon
I should also say that I’ve only been doing the nuts up on the carb to manifold tight when it just bites and then about half a turn.

There should be no gasket between the carb and manifold - only the O-rings that came with the carbs. Use no Locktite. Use spring washers and stop as soon as they are flat - both for carb to manifold and for the four screws in the carbs themselves. Between the head and manifold, there should be a heat insulator, not a gasket. No sealer on any of it.

You probably have the carb body out of round from over tightening. It's a bad idea to sand the slide or carb body - the definition of a worn carb is slop around the slide! If that area is out of round, you can probably fix it. Figure out which way it's out, put it in a vice and VERY lightly apply pressure while moving the slide up and down, release the pressure, and repeat as needed.

texasSlick · Jul 3, 2023

Well, there you have it ..... squeeze first, lap second, send out for resleeving third.
Seriously, from the experience of those replying, you have a chance to salvage the carb. Hope it works for you.

Slick

rweb · Jul 3, 2023

texasSlick said:
Well, there you have it ..... squeeze first, lap second, send out for resleeving third.
Seriously, from the experience of those replying, you have a chance to salvage the carb. Hope it works for you.

Slick

They can be squeezed on the bike with a 4'' C clamp placed side to side below the word Amal. If the slide is stuck it will drop after just a little pressure, apply just a bit more and test without the clamp.

Triton Thrasher · Jul 3, 2023

I attacked mine with something like this.

Tornado · Jul 3, 2023

I think there was an old thread showing someone using a press to push in a length of round stock to correct a warped Amal.

NickZ · Jul 3, 2023

Tornado said:
I think there was an old thread showing someone using a press to push in a length of round stock to correct a warped Amal.

This jig will reliably and safely remove warpage from concentrics.
When a carb warps from over tightening, both the barrel and the flange will be distorted. This jig corrects both.

Amal carbs

nopdog

texasSlick

Mike40M

Triton Thrasher

nopdog

kommando

Cuppy

YING

Pittsboro,NC

baz

L.A.B.

Moderator

figerglas tank resin caming out in carb

baz

EstuaryBoy

concours

robs ss

marshg246

texasSlick

rweb

Triton Thrasher

Tornado

NickZ

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