Adding chokes to my Amals

xbacksideslider said:

Not related to starting but to general running, I’ve often wondered if the hole left by removing the choke slide should be filled. That is, might off idle through 1/4 throttle transition be improved by the elimination of that void? Seems like air may Lose velocity as it tumbleS up into that area. Yes, that void is still there with the choke in the up position but of less volume.

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On my 750 I would just tickle and go. I think I’ve got the mixture a little leaner now so it takes longer to warm up. Does that sound right?

There's a million different points which can be made about the use of choke, bleeders and idle air screw setting relationships.

1) I'm not in any "camp" of using the choke or not using them. I actually stated previously in this thread that maybe people just learn a starting technique that works for them and they stick with it... when the bikes of most people using different starting techniques are actually not all that different and could probably have a different working starting technique.

2) If you cure your stumble off of idle by fitting a different EI that retards the spark to cure that stumble, you still probably have a situation where your idle air screw adjustment position is allowing your A/F ratio to wander out of the "workable range". You're EI is altering the timing to compensate for the stumble that the wandering A/F ratio induced by the idle air screw position that has not been biased to account for the changing A/F effect.

As I said previously, you shouldn't adjust the idle air screw position statically only to set the idle. If you don't lift and lower the slides looking to smooth out the transition to throttle use, while you are making tiny idle air screw adjustments, then you aren't considering the effect that the air screw position has on the A/F ratio as the bike transitions to the other components of the carburetor.

When you see a dyno chart, it should always have a corresponding A/F chart underneath it. With Commandos, you can usually see the wonky A/F ratio right where the idle settings transition to throttle component controlled settings. Understanding and micro adjusting the idle air screw to smooth out that potential stumble is really just biasing the idle air screw position to counteract the effect lifting the throttle has on the A/F ratio.

This is why, the idea of having a "strong idle" which might idle all day, isn't a meaningful statement to me, since I think it's more important to get the idle air screw correctly biased for smoother transition to throttle. If that means it's slightly less perfect A/F ratio at idle, then you trade off smooth accelleration for "all day idling".

My bike idles when it's warm, but poorly when cold. Maybe if I played around with the chokes when it's cold, I could figure out a cold engine choke procedure, but I don't explore that condition because as I said previously, I start my bike and go... By the time I get a half of a mile away, it's warm enough to idle properly for a few minutes, but not 15 minutes... probably because of how I have the idle air screw biased to smooth out transitions to throttle use... rather than have the idle air screw optimized to have the perfect A/F ratio at idle..

I hope that's clearly stated.

I think it's down to environment as much as anything else... Back in the day a commuter here in the UK would need to start the bike at temperatures hovering around freezing, then negotiate stop/start traffic possibly for the entire journey with no hope of being able to pass 30mph....
If you're starting your toy in desert conditions and can pull 5k revs all day after leaving your driveway then obviously way different scenario..

Lineslinger said:

View attachment 17620

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I filled mine with a dob of RTV..... My reasoning is to stop unfiltered air being drawn in, to either be drawn into the engine ( yes this is marginal) but more to stop the slides & parent bores from getting scored

olympus said:

I filled mine with a dob of RTV..... My reasoning is to stop unfiltered air being drawn in, to either be drawn into the engine ( yes this is marginal) but more to stop the slides & parent bores from getting scored

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I have a piece of tape over mine. But there are screwed plugs available.

swooshdave said:

I have a piece of tape over mine. But there are screwed plugs available.

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Amal part: 4/137A. Nice finishing touch to Don's carb gantry. RGM do them. £1.50 each, as cheap as tape or silicone and shinier.

They do not mean fill the hole in the carb top, they mean fill the void in the slide, where the choke, if fitted, would be.

Gadge said:

Amal part: 4/137A. Nice finishing touch to Don's carb gantry. RGM do them. £1.50 each, as cheap as tape or silicone and shinier.

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Gadge said:

Amal part: 4/137A. Nice finishing touch to Don's carb gantry. RGM do them. £1.50 each, as cheap as tape or silicone and shinier.

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holtcorseaux said:

They do not mean fill the hole in the carb top, they mean fill the void in the slide, where the choke, if fitted, would be.

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Yes, I realised that was what was being talked about earlier but the last couple of posts where about the choke entry in the carb top.

The question of filling the gap in the slide is interesting. No idea if it'd make a difference but it would be interesting to try out.

Up until recently I was in the 'Remove' the choke squad.
Glenn's 850 project came to me with new Premiers already installed with the chokes removed and the cable hole properly plugged.
I fought and fought hard starts, cold running for ever. Changed ignitions, coils, plugs, upped the pilots to 19's.
Finally installed the chokes. On/two kick wonder, and needs the chokes to warm up. Then it's fine.
I've had several Nortons with Amals. This is the only one that required chokes. Also, the only one one with Premiers.
I live at Sea Level in So Cal. Mild climate.

o0norton0o said:

2) If you cure your stumble off of idle by fitting a different EI that retards the spark to cure that stumble, you still probably have a situation where your idle air screw adjustment position is allowing your A/F ratio to wander out of the "workable range". You're EI is altering the timing to compensate for the stumble that the wandering A/F ratio induced by the idle air screw position that has not been biased to account for the changing A/F effect.

As I said previously, you shouldn't adjust the idle air screw position statically only to set the idle. If you don't lift and lower the slides looking to smooth out the transition to throttle use, while you are making tiny idle air screw adjustments, then you aren't considering the effect that the air screw position has on the A/F ratio as the bike transitions to the other components of the carburetor.


This is why, the idea of having a "strong idle" which might idle all day, isn't a meaningful statement to me, since I think it's more important to get the idle air screw correctly biased for smoother transition to throttle. If that means it's slightly less perfect A/F ratio at idle, then you trade off smooth accelleration for "all day idling".

I hope that's clearly stated.

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So, let me get this straight. My bike idles perfectly, doesn't stumble off idle but I still have a problem with my idle mixture? Perhaps you've compensated for the limited centrifugal or other straight-line advance by a richer mixture at idle than necessary for idle. Is that your position?

It seems you've spent a lot of time justifying your statements that a bike shouldn't be able to idle for long periods when my original post was meant to convey that the idle mixture is set correctly, a point most seemed to understand.

Anyway, that aside I believe that my informal survey has turned out perhaps slightly in favor of chokes for various reasons, some having nothing to do with cold low speed running.

Having satisfied my curiosity I will, as previously stated, keep an eye out for a complete assembly but won't make it a priority as the work-around is not terrible, just a mile or so of minor aggravation. I certainly won't buy new for what may simply be an experiment should I come to agree with some who say they're troublesome.

Thanks for your and everyone else's opinion and input.

I'm saying that there's more to the idle air screw adjustment than finding the place where the A/F ratio at idle is perfect.

Adjusting the idle air screw to obtain the smoothest transition to throttle use is important too.

To each you’re own. In 47 years of owning Commandos, I have never broken a choke cable. If the spring tension tends to close the choke just tighten the screw in the center of the choke lever. I find the bike starts easier with the choke closed then shortly after running open the choke. If I flood it, choke open and the throttle wide open....one more kick and it goes.

Onder said:

Tickle, kick twice, turn on ignition kick hard and away you go.

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Now, you've kicked it 3 times to start. Why not, turn on ignition, tickle, choke, kick, and away you go?

I can imagine different bikes in different places needing a choke but personally I've never had one on a commando
I tickle the carbs press the button and go
Before the electric start/knee problem I'd tickle the carbs one kick and go
If it was really cold IE ice on the ground and a frozen seat (I hate that!!) I'd tickle the carbs one kick and it'd start
But I'd have to tickle it again maybe one or two more times and then go
Maybe a choke would keep it going?
I never warm the bike up, never let it idle

My bike has NEVER wanted to start. Once I tried kicking it through once or twice with the ignition off then having at it
starting was assured. After years of it being a complete whore my two gentle start kicks and then one go for broke is
no problem because it STARTS.
OK Ill try your tickie and heave and let you know how it goes...all my other brit bikes through the years did.

After tickling the carbs on a cold bike, I always push through once with ignition off...turn on the electrics then kick through. 9 times out of 10 it fires right up.
Choke is based on ambient temperatures whether I use it or not.
cheers,
T

I tickle it well, hold the throttle half open and kick. Starts most every time on the first kick. It roars to life, because I have the throttle lifted, and would probably die if it's dead cold, if I didn't give it a few gentle flutterings. In a few minutes of running, it achieves it's normal steady warmed up engine idle...

I notice some talk of temperatures, I've no problem starting my Commando in the UK without chokes at around 3 deg C (ice & frost still in the shadows at 1pm) just tickle & kick - fell off 30 minutes later on black ice, threw myself 'twixt bike & road (as any caring owner on this list would do ) to minimise damage. Fortunately, no damage to me or bike & she started 1st kick for the (slower) journey home - my son (pillion) found it rather entertaining, his mother less so!