Adding chokes to my Amals

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In 1975 I bought a new 850 Mk2A. It had chokes fitted and it was impossible to start if they were used, so I ignored them. I just tickled both carbs and it would start, usually first kick from cold.

Fast-forward to now and I have a Mk3 with new Premiers (and 19 pilot jets..) It will not start without using the chokes, so the procedure is tickle both carbs, chokes on and brief press of the starter button. I always ride-off within a few seconds of starting and the choke is opened after a couple of hundred yards.
(When I first bought the Mk3, a previous owner had removed the chokes from the original 30,000 mile Concentrics and it started easily from cold after using the ticklers.)

It seems like there are too many variables which can affect the fuelling on Commandos so there's probably no general rule as far as the need (or not) for chokes is concerned.
 
Wow! Such passionate responses!

It seems someone misinterpreted my comments on the nice steady idle to somehow advocating letting the bike idle for extended periods. How my statement that it would idle until it ran out of gas got twisted to that I don't know. BTW, it has a three phase alternator, will maintain above battery voltage at idle, and would, in fact, idle until it ran out of gas!

Yes, my bike starts with a tickle quite nicely when cold but takes some attention to keeping it running until it warms. I have, in fact, taken to getting suited up, starting and riding off slowly. It also starts quite nicely when hot. It does have an issue when it has cooled but not ice cold. I thought perhaps that's where a partial choke would help.

It's mostly moot as it's an E-start and will always start pushing the button.

Since I've never had chokes on this bike and have seen others with them I wondered why they were removed. It seems the answer is: It depends.
 
One thing that is not being mentioned is the temperatures that you start your bike.
A cool day in spring in Southern Ontario, would be 50 degrees F. fast forward to July my temperatures will be from 70-90 F
forum members live in all parts of the world. Someone in South Texas and someone in Scotland may have very different start procedures.
cheers,
T
 
Today a nice comfortable 68, a few days ago, pushing 100. I'll ride into the 40s spring and fall. When I was a young man I'd ride as long as there wasn't snow on the ground. No, I take that back, Working the midnight shift at the airport it was only raining. Crossing the harbor and moving inland it was snowing - a terrible ride home.

Anyway, I'll keep my eyes open for a complete set of chokes and finding them, will probably fit with new cables. It seems people are firmly in one camp or the other so finding out for myself is the answer. It's not a priority as I've plenty to keep me busy.
 
CanukNortonNut said:
A cool day in spring in Southern Ontario, would be 50 degrees F. fast forward to July my temperatures will be from 70-90 F
Click to expand...
True, this. Last weekend my garage was approaching 100°F and the Norton would not start with the choke on.
 
JimNH said:
Wow! Such passionate responses!

It seems someone misinterpreted my comments on the nice steady idle to somehow advocating letting the bike idle for extended periods. How my statement that it would idle until it ran out of gas got twisted to that I don't know. BTW, it has a three phase alternator, will maintain above battery voltage at idle, and would, in fact, idle until it ran out of gas!

Yes, my bike starts with a tickle quite nicely when cold but takes some attention to keeping it running until it warms. I have, in fact, taken to getting suited up, starting and riding off slowly. It also starts quite nicely when hot. It does have an issue when it has cooled but not ice cold. I thought perhaps that's where a partial choke would help.

It's mostly moot as it's an E-start and will always start pushing the button.

Since I've never had chokes on this bike and have seen others with them I wondered why they were removed. It seems the answer is: It depends.
Click to expand...

Jim, you used the phrase, "it would idle until it ran out of gas". I don't think that quality is actually a meaningful indicator of a well adjusted idle, and here's why...

You shouldn't set the idle air screw to just to obtain the "best idle"... You set the idle air screw to get a bike that has the smoothest transition from the idle speed alone up to about 2000 RPM's. Sometimes that may not be the "idle all day long" air screw position, because the idle air screw setting must also compensate for any A/F deviation that may result from lifting the throttle when you accelerate.

If lifting the throttle makes your A/F go lean, then you bias your air screw setting slightly to compensate... and if lifting the throttle makes it go rich, you bias the air screw to compensate for that... It's one of perplexing issues with amal carbs and their clones. Each amal component choice (needle, jets, float height, cut away) defines an RPM range's A/F ratio, and then they overlap as well, so it's a real permutation of possibilities. The idle air screw sets the idle mixture, but also influences the low rpm range, so it's position should be governed by a tedious adjusting process where you lift and lower the throttle off idle as you make minute changes in the screw position to obtain the smoothest transition from idle to throttle rpm's... If that means the idle alone isn't set to the "all day idle" setting, I would still adjust it with that method for the smoothest acceleration... (but that's based on my opinion and experience)

As I said previously, I would like to try my non-choke starting technique on someone's bike who claims their bike always needs choke to start. I wonder if the bikes are actually pretty close to being set up the same, and more than one kind of starting procedure works on all of them. Maybe, we have all just figure out a procedure that works for us so we stick with it....
 
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.
 
This is one of those strings that could go on, and on, and on . . . .

My non-Amal equipped cycles are equipped with choke or “enrichening” levers. To start the bikes the choke needs to be used. Pretty straightforward: Pull the lever, hit the starter button, bike starts and depending on weather back-off on lever as you move along.

On my BSA that originally had Monoblocs and then Concentrics. No choke. Tickle until flooded. Kick bike – after a few kicks bike starts. Blip a few times and pull-away allowing for weather.

On my Triumph with single Concentric I added choke cable and lever to be “authentic”. Never use. I use the tickle and flood technique.

The Commando: Previous owner added a choke lever, cables and chokes. Seeing her garage with three BMWs she believed a bike should have chokes – makes sense based on owning a BMW. Watching her start the Commando she pulled the lever, tickled the carbs (but not flooded) and kicked until it started and immediately disengaged chokes. She had the wrong-side handlebar lever that I didn’t like so I removed choke assembly and the mess of cables under the tank and reverted to the tickle-flood and kick technique.

Maybe I’ll put chokes back on Commando when I get a correct handlebar lever – maybe not. Ambivalent. Yawn.
 
o0norton0o said:
Jim, you used the phrase, "it would idle until it ran out of gas". I don't think that quality is actually a meaningful indicator of a well adjusted idle, and here's why...

You shouldn't set the idle air screw to just to obtain the "best idle"... You set the idle air screw to get a bike that has the smoothest transition from the idle speed alone up to about 2000 RPM's. Sometimes that may not be the "idle all day long" air screw position, because the idle air screw setting must also compensate for any A/F deviation that may result from lifting the throttle when you accelerate.

If lifting the throttle makes your A/F go lean, then you bias your air screw setting slightly to compensate... and if lifting the throttle makes it go rich, you bias the air screw to compensate for that... It's one of perplexing issues with amal carbs and their clones. Each amal component choice (needle, jets, float height, cut away) defines an RPM range's A/F ratio, and then they overlap as well, so it's a real permutation of possibilities. The idle air screw sets the idle mixture, but also influences the low rpm range, so it's position should be governed by a tedious adjusting process where you lift and lower the throttle off idle as you make minute changes in the screw position to obtain the smoothest transition from idle to throttle rpm's... If that means the idle alone isn't set to the "all day idle" setting, I would still adjust it with that method for the smoothest acceleration... (but that's based on my opinion and experience)

As I said previously, I would like to try my non-choke starting technique on someone's bike who claims their bike always needs choke to start. I wonder if the bikes are actually pretty close to being set up the same, and more than one kind of starting procedure works on all of them. Maybe, we have all just figure out a procedure that works for us so we stick with it....
Click to expand...
Well, I've never tried to let it idle until it ran out of gas. It would be silly and serve no purpose. I did try to convey that my idle is correctly set, is smooth, and the bike pulls away properly - when up to temperature. Since it does those things well and I have had to walk away from the bike to get a ten second call that was many minutes and returned to find that my bike was still idling away as I left it and had neither loaded up nor died I conclude, and I believe rightly so, that the idle is set correctly.

Since I have no choice my starting method is likely similar to yours, however, on a low forty degree morning it requires constant attention to keep it running. On an 80 degree day it will almost idle properly immediately.

You are obviously firmly in the no-choke-needed camp and want to convince me. I did ask for cons. You also seem to want to convey, I think, that a properly set idle mixture should not allow the bike to idle indefinitely. Well, I don't think anyone really wants or has a need to idle any more than traffic requires but I disagree with your assertions. At one time I also believed the off-idle stumble was a carburetor issue but pleasantly discovered that went away after fitting a Pazon Altair with NO other adjustments. My conclusion then is that the slight retard of that unit advance curve actually does as advertised and eliminates the stumble. Your mileage may vary.
 
They are fitted at the factory because they were made in England and the temps get down very cold, here in AUS and in my state our winters are very mild so no need for any choke, and if you do remove the chokes the holes where the cables go in the top do need to be blocked, when I brought my Norton new the chokes were fitted but I never used them, but one day got caught out when parked some smart arse seen the lever on my handle bars and decided to turn my chokes on, you know people like to touch things, but of course I didn't know they were on and couldn't understand why my bike was idling high and running like shit till I notice the lever was opened, people just can't help themselves when I got home I removed the chokes completely, that was way back in the late 70s, the same with my old Triumphs never need choke to start them.

Ashley
 
Just as an experiment, today I went out for a brief ride, it’s cool grey and not very pleasant. However, I left the chokes fully open, tickled, kicked and started it first kick. I immediately set off without any concerns, and it ticked over 1/4 mile at the end of the road when I waited to join the main road.
what it will be like in a couple of months time I don’t know yet.
 
Maybe, like ignition timing, our engines are too primitive to respond to subtle nuances, perhaps for most near is good enough, a twist of the throttle and away we go....
Though as 100% of car manufacturers used to fit some form of choke I expect they have their uses (and I do use mine :-) )
 
JimNH said:
Since I've never had chokes on this bike and have seen others with them I wondered why they were removed. It seems the answer is: It depends.
Click to expand...

I believe that sums it up... “it depends”.

I hate the chokes on mk1 Amal’s for the reasons mentioned previously; they can creep on, drop on suddenly, get ingested by the engine, etc. It’s clearly an afterthought of design and the cheapest possible solution.

Mk1.5s are MUCH better carbs in this regard and it’s a shame they’re no longer made.

In the past, with mk1s I’ve removed them whenever possible. But some bikes, without any specific difference or identifiable reason, just seem to need them. My ‘68 T120, with Premiers, is such a bike.

But then again, any carb, or injection, SHOULD need a cold start device of some sort really. If it doesn’t, it can only be because it is rich. Maybe the level of richness is still within what we with old bangers would consider to be ok, but nevertheless, rich it is.
 
My 99 Hayabusa has a ’choke’ lever, the only year they did. What the cable does is slightly rotate the throttle lever raising the tickover speed.
 
A mate of mine who is a very high mileage rider reckons the MK1 amals last longer with the choke slides fitted
He claims the added weight and resonance helps stop the slide
from wearing out!!
 
baz said:
A mate of mine who is a very high mileage rider reckons the MK1 amals last longer with the choke slides fitted
He claims the added weight and resonance helps stop the slide
from wearing out!!
Click to expand...

I‘ve never heard that, but it makes sense IMHO.

The choke slide cannot pull up perfectly straight against the spring can it? It must put some kind of sideways tension on the main slide due to the spring pressure. That tension will reduce (perhaps prevent altogether) the fore and after ‘chatter’ of the slide which is otherwise inevitable due to intake pulses, engine vibration, etc, and which causes most of the wear.

jus’ thinkin’ out loud here...
 
Fast Eddie said:
I‘ve never heard that, but it makes sense IMHO.

The choke slide cannot pull up perfectly straight against the spring can it? It must put some kind of sideways tension on the main slide due to the spring pressure. That tension will reduce (perhaps prevent altogether) the fore and after ‘chatter’ of the slide which is otherwise inevitable due to intake pulses, engine vibration, etc, and which causes most of the wear.

jus’ thinkin’ out loud here...
Click to expand...
He has got through quite a lot of carburetors over the years,not on a commando but a t140v obviously the vibes are different on a bonnie but who knows!
 
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