BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: TIGERJ on 21 September, 2017, 06:11:08

Title: C15 Rebuild Update
Post by: TIGERJ on 21 September, 2017, 06:11:08
Getting out and about in the intermittent good weather.
Starting is first or second kick usually.
However tickover is a problem with the throttle slide not quite returning to the stop.
Only happens when shutting down slowly.
Wondering whether polishing slide/body would help.
As usual comment appreciated
Regards
            Tim
Title: Re: C15 Rebuild Update
Post by: JulianS on 21 September, 2017, 08:49:46
Could be a cable problem - damage or poor routing- or could be a distorted carb body, which is common with old carbs. Loosen the carb retaining nuts and see if it return improves -if it does it is the carb body.
Title: Re: C15 Rebuild Update
Post by: TIGERJ on 21 September, 2017, 10:23:11
Many thanks Julian
Cable is new, oiled and free.
If carb. Body is distorted can this be flatted on a glass plate ?
Any thoughts on polishing?
Tim
Ps You probably remember my carb. Is a bit of a lash up.
Title: Re: C15 Rebuild Update
Post by: JulianS on 21 September, 2017, 11:06:16
You can try flattening the mounting flange on plate glass or a surface plate but you need to make sure you hold the carb square to it or you could make it worse.

As for polishing - if slide a good fit when carb not mounted you should not need to do it you could make an air leak.

Sometimes a distorted carb gets worse when engine hot and you do not want a carb with a sticking slide - dangerous and takes the pleasure out of riding.
Title: Re: C15 Rebuild Update
Post by: Greybeard on 21 September, 2017, 17:09:52
A chap I spoke to at Amal a while ago told me that overtightening the flange bolts/nuts is sufficient to distort a carbs body. They should only be tightened enough to make an airtight seal. If you gradually slacken the nuts and the sticking disappears then its likely that the flange is slightly distorted. As JulianS says, they can be flattened if you take your time over it.

Steve
Title: Re: C15 Rebuild Update
Post by: TIGERJ on 21 September, 2017, 22:14:06
Many thanks chaps.
I will investigate and report.
Title: Re: C15 Rebuild Update
Post by: TIGERJ on 25 September, 2017, 13:06:05
Removed the carb. for inspection.
Flange checked out no distortion.
However found the needle jet blocked.
Cleaned all other parts and refitted.
Stretched the slide return spring slightly.
Only had time last night for short trial but initially seems much better.
Waiting for the rain to stop for proper test.
Tim
Title: Re: C15 Rebuild Update
Post by: om15 on 25 September, 2017, 18:08:58
As my C15 is very low utilisation, a couple of 10 mile runs a month, I always shut off by switching the fuel tap off and letting the carb run dry, also I add redux petrol cleaner to help prevent gumming up of the carb and jets
Title: Re: C15 Rebuild Update
Post by: TIGERJ on 25 September, 2017, 22:44:37
Thanks for the Redex tip what proportion do you use ?
Title: Re: C15 Rebuild Update
Post by: om15 on 26 September, 2017, 17:47:38
Slosh about a tenth of the bottle contents, what ever that might be, into a full tank, do the same with my Street Twin, also try and use decent fuel, Shell or BP premium.