BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: carter_edman on 03 Jun, 2019, 13:27

Title: 1970 A65L Fueling question
Post by: carter_edman on 03 Jun, 2019, 13:27
Recently received a fully rebuilt 1970 A65L. Has new Amal carbs & electronic ignition. It always starts on the first kick and runs great right away.

But after 10-15 mins. riding, it seems like it's not getting enough fuel or air. It wants to die at idle, I need to keep revving, and it loses power. I assume this is a carb adjustment. Is it simply running too rich?

It doesn't need much or any choke when I start it, which also makes me think it might be rich.

Appreciate any advice as I'm learning how to tune these carbs.

Thanks
Title: Re: 1970 A65L Fueling question
Post by: Bess on 03 Jun, 2019, 14:28
Hi,
    This should help:

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

Best wishes...
Title: Re: 1970 A65L Fueling question
Post by: ChrisG on 05 Jun, 2019, 16:00
Sounds like the air screw(s) need a bit of a tweak as when it warms up it's running on fumes. Try screwing them in 1/4 turn at a time.
Title: Re: 1970 A65L Fueling question
Post by: johnjag on 13 Jun, 2019, 09:22
Something like this happened to me on my 95 Triumph Thunderbird. Turned out to be a blocked petrol tank cap breather. When it happens again try undoing the cap as you are coming to a stop and see if it kicks in again.
John.
Title: Re: 1970 A65L Fueling question
Post by: ChrisG on 14 Jun, 2019, 12:41
Thanks John,
It's so easy to bypass the easy fixes and automatically home in on the technical stuff. I wondered why I was getting the carb troubles on my Thunderbolt on an all too regular basis. I was convinced it was ethanol/water in the petrol/very fine muck.
I found out when I emptied the tank and metallic objects were rattling around in there. Turned out to be the main tap brass level tube and both gauze filters. It had been supplying unfiltered petrol for god know how long delivering all the muck continuously.