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So I have a 1970 BSA Starfire [USA import version] that I have had since 2016 and I am finally getting it back together. I needed to buy a replacement carb for the stock AMAL and so bought one of the 928 Premier Concentrics. It arrived with a choke installed and fittings for a choke cable. The existing carb did not have a choke cable. I have heard from friends that I should install the choke, while I have seen youtube videos showing how to remove the choke components and plug the top of the carb. The original parts book shows no choke lever or cable.

My question is this: Should I keep the choke and buy a lever and cable, or should I remove the choke components and plug the hole where the cable adjuster fits in the top of the AMAL....

I had a Thunderbolt that didn't have a choke and it started fine every time. Advice, feedback, etc. appreciated!

Joel


1971 BSA A65T
1984 BMW R100RS
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my 68 A65 thunderbolt needs the choke my 72 T120 bonneville does not i would leave it in and use if needed


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If the new carb has a tickler, you don't need the choke.

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You will need to tickle when starting from cold.
For the first few miles you should need the choke.
If the bike runs well for the first few miles with no choke then your carburation is too weak.
Just my two cents worth of course.

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too weak? dont you mean too rich? i equate weak with lean


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Thanks raf940-----you are correct--- I got it the wrong way around.
Must be this getting old stuff!

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Then,........... there is the Camp that has the advise regarding slide wear. The thinking is then extra slide support would likely help with the wear caused by lied wiggle. (The wiggle is my word..... )
And,........ the choke lever makes a good conversation starter, also a place to hang your helmet.


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Fit a cable and lever, I like using the choke , and dont like using the tickler, if you like the smell of 4 star on your gloves dont fit the choke.
The choke is not great for dead cold starts , otherwise it is very handy. I live on a hill, even dead cold the bike bump starts in 6 feet, 2nd gear 10 mph using full choke no tickle, this is every time i set off. For experiment I have tried kicking it dead cold ( sub 5 C) no tickle full choke, it takes 6 kicks, whereas a tickle would be one or two. The choke is also handy for crude carb jetting tests, a lot better than plug chops, modern fuel is not like the old pictures.


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I'm firmly on the fence about chokes. My first Trident had none and never needed them, but the triple has the magic idle bolt which raises all slides. Tickle, raise the idle a bit and it starts.
My A65 with Amals was cold blooded. It would try to start, but wouldn't stay running or take throttle if the temperature were under about 60 degrees.
Likewise, my current Trident had no chokes when I bought it. I could start it in warm weather. However, the new Premiers came with chokes, so I bought the cables and now I use them. We had a T160 in the shop where I worked which absolutely refused to start without full choke.
All depends on the bike. In your case I would probably leave the choke slides out and plug the choke cable hole with silicone. See how it works that way and decide. Just be prepared to use the throttle to keep it running until you ride off.
BTW: The new carbs come with extended ticklers, your fingers stay dry when using them. laugh


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If you haven’t previously run the bike then for the sake of one cable and a lever I’d fit the choke, that’ll give you all the options come first start up. If it turns out that the bike doesn’t need it from cold then fine but if it’s not there and you struggle to make it fire you’ll be wondering.

Even on a warm UK day and a good tickle my bike won’t fire up from cold without choke, when it does choke is knocked off immediately so it’s almost redundant but I’m still glad it’s fitted.

Chris


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Originally Posted by Chris Brasier
If you haven’t previously run the bike then for the sake of one cable and a lever I’d fit the choke, that’ll give you all the options come first start up. If it turns out that the bike doesn’t need it from cold then fine but if it’s not there and you struggle to make it fire you’ll be wondering.

Even on a warm UK day and a good tickle my bike won’t fire up from cold without choke, when it does choke is knocked off immediately so it’s almost redundant but I’m still glad it’s fitted.

Chris
i'm with Chris here - keep the choke - whether you need it or not, it's there and you have the option. remove it and you've boxed yourself in. i'm in florida and it's warm most days - other days, just plain hot. 99.9% of the time, a tickle is fine, but every once in a while, the old girl needs a little help. besides, IMO, british bikes look naked without that little chrome lever.

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Just one more thing to vibrate and fall off. This is not a once and for all decision. Leave it off and if you find you need it put it on!

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If you decide to plug the cable entry, use something soft.

https://www.britbike.com/forums/ubb...e/what-did-my-thunderbolt-eat#Post450116

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I have 3 unit singles. Stock, none of them had chokes. I put chokes on all 3 when I was putting them together because it seemed like a good idea. However, for whatever reason, they all start more easily when cold without the chokes. Maybe BSA knew what they were doing when they left chokes off of the unit singles. Go figure.

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Originally Posted by edunham
I have 3 unit singles. Stock, none of them had chokes. I put chokes on all 3 when I was putting them together because it seemed like a good idea. However, for whatever reason, they all start more easily when cold without the chokes. Maybe BSA knew what they were doing when they left chokes off of the unit singles. Go figure.

Ed from NJ

I did the same but find the choke does work after that annoying 10/15 minute stop where you kick away and nothing happens with no tickling but if you tickle it floods, add the choke and turn off as soon as it catches.

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Wow, thanks for the feedback all. So, I guess there’s three camps of opinion:
1) No choke, as BSA didn’t supply them for unit singles.
2) Yes choke, as then it provides the option of having one if needed (and with the added benefit of cool chrome lever to hang helmet).
3) Try it without choke, and add later if it needs choke.

(Maybe a fourth camp of dedicated fence sitters)

I’m definitely on the fence, but because I’ve never started the bike, I may spring for the lever and cable just to overreact 😬


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The '68 Firebird Scrambler here with 930's doesn't need a choke to start. The '68 Spitfire with 932's needs the choke to start.

Other non-helpful information:
The Hornets and Wasp with and without chokes will start sometimes and sometimes not.

I've choked a few times myself.


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Quote
The '68 Firebird Scrambler here with 930's doesn't need a choke to start.

Same here, my 68 Firebird is fitted with twin 930's and seems to start easily enough just using the ticklers on both carbs.

I guess there are a lot of factors that can influence how easily the bike starts, including the fuel condition, electrical supply, and ambient temp.

I think what I would do is keep things simple, just use the tickler and see how you get on. If starting becomes a problem you can always add the choke later.


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OK, so I talked with Peter Quick at BSA Unit Singles, where I purchased the 938 AMAL premier. None of the Starfires had chokes from the factory. He says the new Amals are all set up for Triumphs, as those are the most numerous. In order to use the carb cap or top that came with the new AMAL, you have to drill out the threads on the throttle adjuster to fit the BSA cable, and the choke cables available are a pain in the arse. He recommended using the old AMAL cap, as it's totally compatible with the new AMAL and just dispensing with the idea of a choke... So, like water, I like the path of least resistance, so no choke for now...Thank you all for the input, its great to have this forum as a resources. I hope I can contribute in the future!

Joel


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Quote
He says the new Amals are all set up for Triumphs, as those are the most numerous.
Hmmmm. The only Triumph to use the top fitted to the 300/301 series of the Concentric supplied by Burlen was for the 1968 model.
There is more than price to consider when buying a AMAL Concentric carburetor. Buy from a dealer who will match the top to one of the four used by AMAL and has the proper jetting and slide. Buying a generic carburetor for price can be more expensive when you have to sort it out having to buy new bits to get it to work.

If you look into the science of gasoline, and the 10%, 50% and 90% evaporation points, you will discover that a choke is required. If an engine starts from cold, and runs without some form of enrichening, the air fuel mixture it too rich.

Last edited by John Healy; 06/03/21 2:39 pm.
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