New amal premiers wont stay idling

joshtjeerdsma · Nov 4, 2015

I just finished a bunch of work on my 72 combat which included installing a set of new amal premier 932s. I feel that I have them synced fairly well. It took a lot of kicks to initially get the bike started and it took a bit to get it running smooth. Now it starts on the second kick, an idles smoothly. The problem is that it only idles for a bit then slows down and quits. It seems like the float bowl is running out of fuel. Could this be a float level issue? If so, can I adjust it with the carbs still on the bike? I was hoping the new premiers wouldnt need much tweeking to get right. Thanks, Josh.

L.A.B. · Nov 5, 2015

Bowtoy70 said:
It seems like the float bowl is running out of fuel. Could this be a float level issue?

Yes, it could be (but doesn't necessarily mean it is).

Bowtoy70 said:
If so, can I adjust it with the carbs still on the bike?

Yes, but I suggest you check both fuel levels first, before attempting any adjustments: http://amalcarb.co.uk/optimising-mark-1 ... uel-levels

Paddy_SP · Nov 5, 2015

Also, it'd be worth checking everything upstream of the carbs to ensure that there isn't a fuel supply issue. If the taps or fuel cap breather are partly blocked, for instance, it could make idling problematic.

Triton Thrasher · Nov 5, 2015

How does it run when not idling?

Gasket fouling the float is common. Float needle sticky in the seat is not unknown.

concours · Nov 5, 2015

Cables free? A too lean mixture can cause a hang throttle

Deets55 · Nov 5, 2015

Open the gas cap when the engine slows down, you might be getting a vacuum in the tank.

dennisgb · Nov 5, 2015

If the engine throttles up when running normally the fuel level is not low. Running out of fuel usually occurs at higher RPM's.

As other's have said could be any number of things, but I would suspect pilot adjustment first, particularly since you had starting problems initially.

Here is some info on how to adjust idle on Amals:

http://www.amr-of-tucson.com/idle_adj.html

Make sure the choke is not partially engaged also.

kommando · Nov 5, 2015

If you have electronic ignition with idle stabilisation this interferes with pilot jet tuning, as the revs drop it advances the ignition to bring the idle speed up so as you go lean or rich it appears the engine runs better but its not. Colortune gets round this as you tune instead to the colour of the burn but as long as you know the cause you can still tune by ear.

Paddy_SP · Nov 5, 2015

How much fuel do you have in the tank? If it makes a difference having it on the centre stand rather than the side stand, suspect a tap!

joshtjeerdsma · Nov 5, 2015

I have pazon sure fire ignition, which i dont believe has idle stabilization. I believe it was staying running when on the throttle, just not at idle. I have a nearly full tank with premium ethanol free fuel. I tried with both petcocks on and the bike on the sidestand as my center stand recently broke. I was hoping the pilot jet wouldnt need messing with as they are new carbs. The jetting is all the same as the original carbs. I will ty some of your suggestions tonight and appreciate all the input.
Josh

grandpaul · Nov 5, 2015

I have heard some reports of the new Amal Premiers having production flash debris in some of the passages.

Thorough strip-down and blast-out of all passageways before installation is step 1.

Paddy_SP · Nov 5, 2015

Bowtoy70 said:
I have a nearly full tank with premium ethanol free fuel. I tried with both petcocks on and the bike on the sidestand as my center stand recently broke.

Josh

It's good to eliminate the silly stuff first - good luck with tracing the cause!

pete.v · Nov 5, 2015

grandpaul said:
I have heard some reports of the new Amal Premiers having production flash debris in some of the passages.

Thorough strip-down and blast-out of all passageways before installation is step 1.

With my premiers, there was a clear grease, like an oring lube or the like, inside where the air screw bottomed. It was just enough to effect my idle and my patience. These were like this brand new out of the box.

Compressed air and carb cleaner took care of it.

dennisgb · Nov 5, 2015

Bowtoy70 said:
I have pazon sure fire ignition, which i dont believe has idle stabilization. I believe it was staying running when on the throttle, just not at idle. I have a nearly full tank with premium ethanol free fuel. I tried with both petcocks on and the bike on the sidestand as my center stand recently broke. I was hoping the pilot jet wouldnt need messing with as they are new carbs. The jetting is all the same as the original carbs. I will ty some of your suggestions tonight and appreciate all the input.
Josh

Not sure your level of expertise, but pilot screws (not pilot jets) need to be adjusted because each engine is a little different and location (elevation particularly) effect the fuel required. The mixture at idle needs to be adjusted via the pilot screws. Carbs are not adjusted to your bike out of the box.

Also the others who suggest there could be foreign material in the passages even tho the carbs are new have experienced this.

The pilot circuit is very sensitive to dirt and needs to be clean and adjusted to get proper idle. Your description indicates one or the other or both.

Edit: Just to be clear, this is the air screw on Amal's. Terminology is different for different carbs. Some adjust fuel amount while others adjust air. Read the info I provided earlier which is specific to Amal's.

joshtjeerdsma · Nov 5, 2015

I synced the carbs ghetto style with popsicle sticks and got the throttle slides at the same height and moving in sync. I then adjusted the air screws out 1 1/2 turns and adjusted the idle screws(throttle slide screws) until I got the bike to idle around 1000 rpms. The bike starts and idles high at first then slowly goes down to a perfect idle. It then idles perfectly for about 10 seconds, then slows till it dies. The throttle cables are new and are free to move.

L.A.B. · Nov 5, 2015

Bowtoy70 said:
I then adjusted the air screws out 1 1/2 turns and adjusted the idle screws(throttle slide screws) until I got the bike to idle around 1000 rpms. The bike starts and idles high at first then slowly goes down to a perfect idle.

"1 1/2 turns out" for the pilot air screws is only a basic starting point and the correct air screw setting could be anywhere from 1/2 to 2 1/2 turns out?

Deets55 · Nov 5, 2015

My Premieres right out of the box had loose pilot jets. Also as Les says 1.5 turns is a starting point for mixture screw, mine are about 3/4 of a turn out. I can bring my idle down to 600 rpm if I want. I try for 950-1000.

grandpaul · Nov 5, 2015

You don't want a big air cooled twin lugging anywhere below about 900 RPM at idle.

1up3down · Nov 5, 2015

I too have new Amal Premiers

air screws set at one and a quarter turns out

you may be too lean at one and half out and so it dies

try enriching by turning them in a quarter at a time and see

you are keeping the battery charged and plugs are clean looking.....

Torontonian · Nov 5, 2015

Betcha it's cables ! :idea:

New amal premiers wont stay idling

joshtjeerdsma

L.A.B.

Moderator

Paddy_SP

Triton Thrasher

concours

Deets55

dennisgb

kommando

Paddy_SP

joshtjeerdsma

grandpaul

Paddy_SP

pete.v

dennisgb

joshtjeerdsma

L.A.B.

Moderator

Deets55

grandpaul

1up3down

Torontonian

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