BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: Hancock on 20 Aug, 2019, 10:49

Title: Pilot jet screw b40
Post by: Hancock on 20 Aug, 2019, 10:49
Hello all, having trouble getting the bike to run smoothly when in third or top at low throttle. I've been messing around with the pilot air screw and throttle stop. Can anyone tell me where the pilot jet screw should be set,the one under the covering nut.1967 b40 Thanks
Title: Re: Pilot jet screw b40
Post by: hoogerbooger on 20 Aug, 2019, 20:18
reference to covering nut confuses me as I'm presuming you have a Amal Concentric carb.

If so the the pilot air screw should be somewhere close to 1 and half turns from fully in. This is what Amal say is the starting point for tuning the pilot air circuit.

OR if you mean the screw in pilot air jet on the amal premier concentric carb  ? .......then I'm not sure !


Following links may assist  but mainly don not address the premier air jet:

http://amalcarb.co.uk/downloadfiles/amal/Mk1_Hints_and_Tips.pdf

http://www.jba.bc.ca/Bushmans%20Carb%20Tuning.html

https://www.princeton.edu/ssp/65-cub-data/library/amalbritbike.pdf
Title: Re: Pilot jet screw b40
Post by: TTJOHN on 21 Aug, 2019, 09:04
Nothing to do with pilot jet, if as you say in third or top gear, this is where your main jet is in, pilot jet is only on tick over. Check for air leaks on carb intake first.

Regards TTJohn
Title: Re: Pilot jet screw b40
Post by: Hancock on 21 Aug, 2019, 14:32
Will do thanks