Hey guys
Just got my 1943 bsa m20 starting up.
However when i open up the air control lever (choke) the engine revs up
very loudly. I cleaned the carb as thouroughly as i could, took everything apart made sure there is no blocked jets. i dont have a ultra sonic so i did it by hand. there could be a small air leak in the conection from the carb to the head, i replaced the gasket but the new one slightly thinner than the old.
Was looking for thoughts ideas on how / why the engine speed increases with more air flow.
also to note i am pretty green when it comes to mechanics. this bike was sitting in storage for the last 30 years at my dads. when i first saw the m20 sittin there i instantly fell in love. So now i am trying to get this bad boy going and learning all i can. Henk's cd and this website has been a amazing resource!.

email (option): demonpatch69@yahoo.com

Hi JPatch
And congratulations for your "new" vehicle!

First, I would check that all surfaces are straight and not deformed,
Both on the carb output (Barrel side) and spacer,
And also that the spacer is not cracked.

Next, if the carb is clean, and has the correct jetting and slide,
(See tech' section of forum)
And that the choke guide and spring are there.
Screw in the air adjust screw all the way in,
Then open 1.5 turns as a starting point.

Turn the engine and adjust the air and idle WHEN IT'S HOT, after/during a ride,
And then you are done.

The choke is only there for starting, no need to use it while riding,
And the through is that the choke is not needed at all..
It would start right up in any weather with a bit of flooding,
Using the tickler.

Another thing worth checking, if you want to keep the choke,
Is if it is not stuck in its "rail" in the slide,
And then when retracts, it may pull the slide with it..

Good luck,
Noam.

email (option): noam10@gmail.com

So having the air intake blocked by choke at all times is ok as long as i get a good idle ?

also my carb tickling the carb seems to have no effect. Correctly tickleing the carb should result in a little fuel bleeding out right?

there is only one clip setting in the float needle so adjusting the float level is impossible. the banjo connecting nut appears to be the correct size according to amal website for the 276c/1b

email (option): demonpatch69@yahoo.com

It sounds like the tiny hole on the engine side of the throttle slide and the one just on the engine side but inside the throttle slide may be blocked and you are compensating by keeping the choke on. It would be worth cleaning them out. Before you undo the carb from the engine you should remove the float assembly then slacken the nut at the bottom of the carb body, then undo the carb and remove the throttle slide as a unit, you can just leave the cables and slide hanging, no need to remove these.
When it is on the bench you should remove the tick over screw, the idle air screw and the jet and holder now you are left with just the body with the brass jet block then you simply get a piece of wood and using a hammer, tap out the brass jet block from the top of the carb body taking care not to damage it. On the engine side of the jet block you will see some tiny holes that you can clean out with a strand of electrical wire, there are matching holes on the carburettor body that are so tiny you may not even see them at a glance, clean these out too and simply reassemble.

email (option): davmax@ntlworld.com

So having the air intake blocked by choke at all times is ok as long as i get a good idle ?
[/quote]

No..
If the choke slide will always be in a "closed"/chocked position,
You will never be able to get the correct air-fuel ratio under a normal operation.

email (option): noam10@gmail.com

Did he say it was fully closed?

email (option): davmax@ntlworld.com

He said "air intake blocked by choke at all times "...

email (option): noam10@gmail.com