Amal 932 and detachable pilot jets

Amal says that for 4 stroke engines, the 932 Amals have a bush pilot jet. The detachable one should be for 2 stroke engines only. (or mainly)
Recently I was recommended to mount a detachable pilot screw as well. This should be advisable with the "modern" lead-free gas. Can anybody confirm this ?

Re: Amal 932 and detachable pilot screws

If your bike is running good, then don't change anything.
I went from leaded to lead free & didn't change anything.

Re: Amal 932 and detachable pilot screws

I wished it was (running good I mean). "If it ain't broken, don't fix it" is an advice I always respected. :wink:

So maybe I should have explained the issues I'm faced with. When new Amals were fitted - after I became the new owner of the bike on the right - the Production Racer (Combat 750) started at first kick, idled immediately but also smoked heavily (black smoke, not blue) so the adjustment was definitely too rich...
After 1000 miles, when smooth starting and iddling got worse, it was time to check the adjustments. I won't explain all I've tried but eventually I found the synchronising being a mess, one of the cilinders sputtered, etc. etc.

After a lot of trials, idling is excellent now, I changed the 105 (!) needle jets by # 106 and the bike runs well.
The only problem that remains is this: when idling for a while, slowly opening of the trottle causes stalling. (quite annoying at traffic lights). Today I changed the needle clips to the lower groove. The sudden stalling disappeared but the engine isn't as smooth as before (too rich I guess)

main jets: 230

(I hope it's understandable - even in my own language it wouldn't be obvious to describe) :?

Re: Amal 932 and detachable pilot screws

I can see now you have fustrating problem.
I really cannot remember about any pilot jets in mine, as I last had my carb's apart 4 years ago, but it is as standard, even though the motor is quite highly tuned.
Rough sequence of carb. tuning, pilot air screws out equal amounts, about 1 turn, unscrew idle screws until the slides are not touching them. Start bike & lower revs to see if firing equally on both cylinders, as you are resting on the cable now. Adjust if required. Once the cable pull is equal, screw up idle screws to get an even tickover on both cylinders.
With your engine hot, unscrew the pilot screws one side at a time & see if the motor speeds up, if it doesn't screw them in until 1/2 turn out & start screwing them out to see if engine speed rises. Keep going until the engine speed stops rising, then in 1/4 turn. This should hopefully set your pilot air mixture. If you can get a colourtune for this, it is easier.
I presume you have the correct needle etc.
Those bell mouths don't help, they actually go better without them, but it won't look as good.

Flo said:

Keep going until the engine speed stops rising, then in 1/4 turn. This should hopefully set your pilot air mixture.
.

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This could be the clue. I find it strange to turn the pilot screw in that much (making the mixture richer, right ?) when by ear the "best" mixture is reached.
I'll give it a try. Thanks for your help Flo. I'll keep posting.

Nevertheless, about the detachable pilot jets: if anyone has any experience with those, I would be grateful hearing from you.

Re: Amal 932 and detachable pilot screws

Sounds like your slide cutaway needs adjusting rather than the pilot jet or the slides are wearing and are causing problems to the mixture as the slides lift for the throttle stops.

Re: Amal 932 and detachable pilot screws

As you turn the screw out it weakens the mixture & makes the engine speed rise, but it will reach it's limit. A 1/4 turn back in just makes sure it is not too weak. Mine is out about 1-3/4 turns, a surprising amount, as the o ring is just showing.
Set many bikes this way, & also many cars with Strombergs & SU's as they work directly on the main needle.
As for replacable pilot jets, I still cannot remember, but I can definately remember them on other bikes.

Re: Amal 932 and detachable pilot screws

kommando said:

Sounds like your slide cutaway needs adjusting rather than the pilot jet or the slides are wearing and are causing problems to the mixture as the slides lift for the throttle stops.

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Agree, the slide cutaway is probably wrong. On my Commando with a single Amal, it would hesitate off idle, if I remember correctly, the slide cutaway was a "3" and the next one up was a "3½" Instead of replacing it (I think it would have taken a lot of time to order or something like that or maybe I was just too cheap :lol: ) I filed it myself and it worked perfectly after that.

Jean

Re: Amal 932 and detachable pilot screws

I'm going to convert my cards to a screw-in pilot. I think a buried bush is bull.

Re: Amal 932 and detachable pilot screws

swooshdave said:

I'm going to convert my cards to a screw-in pilot. I think a buried bush is bull.

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If so, do you think the bush jets might stay in place ?
(together with the detachable ones I mean)

Re: Amal 932 and detachable pilot screws

about the slides: those are 3 1\2, chrome plated and only 2000 Km "old".

Re: Amal 932 and detachable pilot screws

hold it, Ludwig !
Very good questions indeed but don't forget the title of this thread: it's about jets that are 6 mm. big, remember ? Shouldn't it be a bit exaggerated to take apart the whole bike to solve this problem ? :shock:
Don't forget it rides very well so far, and I want to check things one at a time...
I'm not a follower of the "if it isn't broken, dismantle it and find out why" - method, and changing 2 suspisious things at a time is never a good idea if you want to find out what the cause was.

So far, I followed the carb tuning method Flo explained. Seems to be a big improvement but I tested only inside my workshop, waiting for some better weather to go for a testrun.

Re: Amal 932 and detachable pilot screws

I still have my bull buried bushes but it is not really a big problem to maintain them.

When converting to the screw-in idle jets you need to bore out the original bushes. 1/8" comes to mind. Try searching this forum or possibly the Brit Bike forum posts by John Healy.

Re: Amal 932 and detachable pilot screws

batrider said:

When converting to the screw-in idle jets you need to bore out the original bushes.

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That's exactly what I would expect. I can hardly imagine that idling would be possible if both the screw-in and the bush jet are mounted (as I was advised). (unless my understanding of the pilot jet circuit is wrong)