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[Andy C]

Final comments from me for now......

The reason for removing the choke slide is that there was not one fitted to the original MK1, the bike used to reliably start simply by tickling the carb, so I had assumed that it would be the same with the premier carb, hence reason for removing it.

I did blank off the choke cable hole with the correct Amal blanking plug.

Our hosts recommend using the choke so I am going to re instate it and see how it goes, our hosts also said that the standard pilot fitted to these carbs - 17 is good for almost all applications which is the size of jet I have fitted.

With the old MK1 the bike would reliably start 2 or 3rd kick, and would only spit back when cold.

Plan for now is to re insatate the choke slide & handlebar lever and see how it goes.

It's all a bit dissapointing as I thought it would be a simple off with the old and on with the new - but like some things in life it is never easy, and I dont give up easily.

I'll dig out this thread again and update it once I have had a chance to try the choke.

Sorry if I have not addressed everyones comments so far - everyones input is useful !!

[stinkwheel]

You can get a brass, chokeless slide for them direct from Amal. It's also good and heavy so gets a bit of a gravity assist on closing.

[Presto]

The throttle valve that has no facility for a choke is the valve used with the Mk 1 ½ Concentric. This version of the Concentric used a starting jet, like the Mk 2 Concentric, and therefore no need for a choke slide.

My question is why would anyone want to remove the choke from a Mk 1 Concentric? I can see no advantage and a number of disadvantages. Ah well - live and let live.

[Count Johnny]

Mikuni VM34. That is all.

[TexasChris]

Hi Guys,
Somewhat related question...its been mentioned that the standard pilot jet is a 17? I pulled mine last night and could find no markings on it to confirm its size? I was considering ordering a size up...but wanted to be sure what I had beforehand. Should there be a mark? Am I missing summats? Is there some other way to tell?
Thanks,
Chris

[Presto]

Premier pilot jets are sized differently from standard Mk 1 Concentrics. Instead of being calibrated by fuel flow, Premier pilot jets are calibrated by the diameter of the bore of the jet in thousandths of an inch.

Amal fit Premier pilot jet size 17 as standard.

If difficulty starting or an erratic tick-over a 19 pilot jet may be used. These 2 jets cover about 99% of applications in a MK 1 Concentric.

There are a series of rings engraved on the jets to indicate sizes.

Approximate equivalent jet sizes between Mk 1 Regular and Premier carbs: (Regular: 20) – Premier: 15 [1 ring]; (25) – 17 [2 rings]; (30) – 19 [3 rings]; (35) – 21 [4 rings]; (40) – 23 [5 rings]

Hope that makes sense!

[TexasChris]

The rings! I thought there must be some kind of mark to de-note the different sizes! Thanks. I'll check for those this evening and probably end up ordering a 3 ring/19.
Thanks again.

[stinkwheel]

My question is why would anyone want to remove the choke from a Mk 1 Concentric? I can see no advantage and a number of disadvantages. Ah well - live and let live.

Because it's prone to seizing, clutters the handlebars with an extra lever and appears to serve no useful function on a 350 indian bullet. Certainly didn't on mine, tickle once and fire up. Just had to remember to park with it fully on so it could be pulled back fully off again prior to starting to prevent seizure of either the choke itself, the cable or both. The lever also periodically worked a bit loose and wiggled its way partially on which you didn't notice until you found the bike pulling badly up a hill.

Fixing a part you never use gets somewhat boring after a while. As does periodically having to make a new cable for it.

[singleminded]

My 625 Bullet has a 32 mm Mk1 Concentric carb, with a choke fitted.

The bike will not start from cold without use of the choke, even when the carb is tickled until it overflows.

Similarly, my 850 Commando with twin Premiers needs choke from cold.

[Sebas008]

Throttle stop ?
Air leak?
Float needle not seating?
Float height?
I also remember trying to set up a monobloc with not enough rachat crédit locataire fuel in the tank! that took some time for me to work out! putting the tap to reserve helped here (it was just on the edge between main and reserve)
Can't think of anything else
Hope this helps Dai

This is a good article because there are many tips and also many advices that will be very useful for me.