BritBike Forum logo
BritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike Sponsor SteadfastCyclesBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorHepolite PistonsBritBike Sponsor
Upgrade to: Gold Membership | Premium Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
Kenny
Kenny
Oklahoma
Posts: 28
Joined: July 2003
ShoutChat Box
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
a word from..
Manuals on DVD (Shipping included)
Previous Thread
Next Thread
Print Thread
Rate Thread
BSA C15 Won't Idle
#801853 03/18/20 10:23 pm
Joined: Mar 2020
Posts: 6
Britbike forum member
OP Offline
Britbike forum member
Joined: Mar 2020
Posts: 6
Hello everyone,

I recently got a BSA C15 and have been working on it for the past couple of months. Everything was going well until it started randomly stalling while at a stop. Figured it was because of the rust in the tank, so I evpo-rusted the tank, installed an inline filter, and cleaned the entire carb. Started her up today, and she runs well, but it seems impossible to get a consistent idle. I even took out the pilot jet again and used wire to clean out it? I am wondering what it might be, my air filter seems to be fine. The upper ranges of the throttle work perfectly and sound great, but just that first 1/8 runs a little rich, and the idle dies immediately.

If anyone could offer any help on what the problem might be, I'd be ever grateful.


smile
Support Your #1 BritBike Forum!

Check out British motorcycles for sale: British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Re: BSA C15 Won't Idle
aidangoodmn #801865 03/18/20 11:41 pm
Joined: Dec 2018
Posts: 107
Likes: 1
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2018
Posts: 107
Likes: 1
Hmmm ………. a sage once told me that 90% of carburettor problems are the spark plug.

The right plug (Champion) with the right lead, made all the difference to my B44.

Re: BSA C15 Won't Idle
aidangoodmn #801866 03/18/20 11:49 pm
Joined: May 2013
Posts: 6,686
Likes: 19
Britbike forum member
Offline
Britbike forum member
Joined: May 2013
Posts: 6,686
Likes: 19
Drain the tank, fresh fuel and drain the carb as well. Adjust idle mixture once you’ve done at least 10 miles, probably more this time of year, you want the engine nicely warm.

Raise the idle mixture (horizontal screw) until the idle
Speed starts to drop off, then increase it until again it starts to drop off (or 1/16- 1/8 a turn) then adjust the slide screw to suit.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: BSA C15 Won't Idle
aidangoodmn #801868 03/19/20 12:06 am
Joined: Aug 2001
Posts: 5,164
Likes: 15
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2001
Posts: 5,164
Likes: 15
Check how sloppy the slide is, it should have a little play , if you can shove it around and hear clicks, its worn, and coming just off idle is where it comes most into play. A badly worn throttle slide will make a stable idle almost impossible, If its not that make sure your advance retard is working well, and you have a good healthy spark.
If you have dirt in the fuel get familiar with cleaning the pilot jet, its the smallest important hole and it is the first to block.


71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: BSA C15 Won't Idle
aidangoodmn #801906 03/19/20 7:22 am
Joined: Aug 2001
Posts: 8,200
Likes: 9
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2001
Posts: 8,200
Likes: 9
Clean the pilot jet.

Keep the points adjusted and clean.

Last edited by triton thrasher; 03/19/20 7:25 am.

Amateur Loctite enthusiast.
Re: BSA C15 Won't Idle
aidangoodmn #802053 03/20/20 6:57 pm
Joined: Jun 2015
Posts: 192
Likes: 2
Britbike forum member
Offline
Britbike forum member
Joined: Jun 2015
Posts: 192
Likes: 2
could be a number of things
Either way I’d start at the beginning
Gap the points and thoroughly clean the plug.
Then remove the carb and remove the slide and float bowl .
Clean in petrol and if you have an air line blow out the main jet and pilot jet .
Remove the air screw and blow out any crap .
Assemble the carb in a clean environment, make sure the needle valve on the float is clean , then screw in the air screw till home , then back off 1 1/2 turns out .
Refit the carb , use a new gasket, if using a phenolic spacer put a bit of Vaseline on the flange o ring and gasket sealer on the head side .
Bach the idle screw right off and observe the slide, screw in TIL it just starts to lift the slide then screw in 2 full turns .
Start the bike and go for a short run , then reduce the idle or increase till your happy , then do the idle mixture turn either in or out till the tick over increases , when you get the fastest idle turn out 1/8 turn .
You may now want to check your ign timing and then adjust idle accordingly
Ps. Do NOT over tighten carb flange nuts , this has a habit of distorting the body .
Hope this helps


1969 BSA A65 Lightning
1994 moto guzzi California
Triumph sprint GT
1971 BSA B50 Victor special
1968 BSA B44 SS
1 member likes this: aidangoodmn
Re: BSA C15 Won't Idle
richiedan40 #803194 03/28/20 7:26 pm
Joined: Mar 2020
Posts: 6
Britbike forum member
OP Offline
Britbike forum member
Joined: Mar 2020
Posts: 6
Thanks for the reply!

I was finally able to get the bike idling, with the everyones advice and help. It seems that there is still a lingering issue. Everything will start fine, but the idle will be really low, almost sounds like poping and boging. But if I blip the throttle, then the idle shoots back up and sounds great, just idling a lot higher. I was driving around and sometimes it completely misfires and slows down rapidly, happens sometimes when I give it some throttle. Other times it runs perfectly normal.

Is this an issue with the ignition timing? I have one of the eailer model bsa c15s that dont have an inspection cap to set ignition timing. How would I go about adjusting this? If it is at all the problem.


smile
Re: BSA C15 Won't Idle
aidangoodmn #803395 03/30/20 9:33 am
Joined: Feb 2006
Posts: 878
Likes: 1
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2006
Posts: 878
Likes: 1
Originally Posted by aidangoodmn
Thanks for the reply!

I was finally able to get the bike idling..... It seems that there is still a lingering issue. Everything will start fine, but the idle will be really low, almost sounds like poping and boging. But if I blip the throttle, then the idle shoots back up and sounds great, just idling a lot higher. ...........I was driving around and sometimes it completely misfires and slows down rapidly, happens sometimes when I give it some throttle. Other times it runs perfectly normal.

First part could be throttle cable binding.

Second part could be battery not catching enough charge, or dodgy ignition switch


'51 C11 in a '54 C10L frame. Back on the road...
'70 Triumph Trophy 500. Next on the bench for a refresh!
'72 Triumph Tiger 650. Back on the road...
Re: BSA C15 Won't Idle
aidangoodmn #803401 03/30/20 9:52 am
Joined: Dec 2004
Posts: 10,598
Likes: 21
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2004
Posts: 10,598
Likes: 21
The AAU in the distributor could be hanging up too advanced coupled with weak springs, distributor shaft is loose in the bushes and points gap is varying depending on tea leaves and wind direction.

Re: BSA C15 Won't Idle
aidangoodmn #803499 03/31/20 6:18 am
Joined: Mar 2020
Posts: 6
Britbike forum member
OP Offline
Britbike forum member
Joined: Mar 2020
Posts: 6
I believe it now to be the AAU distribuer. Ive been experiencing kickback from the kickstart since i got the bike. And after messing with the wire, I was able to get everything a little more stable. What would be the best way to fix the advance, a replacement or repair? The shaft doesn't seem to be loose, but the wire is a bit rusty at the connection point. And I would believe that the springs will have lost strength too.


smile
Re: BSA C15 Won't Idle
aidangoodmn #803508 03/31/20 9:32 am
Joined: Dec 2004
Posts: 10,598
Likes: 21
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2004
Posts: 10,598
Likes: 21
I had the low tension cable to the Distributor internally break down until there were only 2 strands left conducting electricity, result was intermittent ignition. Took ages to work that one out, replacing with new cable was an immediate fix. The capacitor/condenser under the cover may be going bad, any ignition capacitor that can be adapted will fix that but check the link below first.

I upgraded to the F type engine to get rid of the distributor but that is an involved change with lots of parts to find.

Peter Quick at BSAUnitsingles.com is a vital source for spares

His version of the condenser

https://www.bsaunitsingles.com/item.wws?sku=425377

Speak to him direct ref advance springs.

Re: BSA C15 Won't Idle
aidangoodmn #803518 03/31/20 11:54 am
Joined: Jun 2015
Posts: 192
Likes: 2
Britbike forum member
Offline
Britbike forum member
Joined: Jun 2015
Posts: 192
Likes: 2
what would eliminate a lot of problems would be electronic ignition , electronic advance ...so no need for bob weights and springs , and no more points and condenser.
plus easier starting and smoother running .
worth a thought.


1969 BSA A65 Lightning
1994 moto guzzi California
Triumph sprint GT
1971 BSA B50 Victor special
1968 BSA B44 SS
Re: BSA C15 Won't Idle
aidangoodmn #803532 03/31/20 1:40 pm
Joined: May 2013
Posts: 6,686
Likes: 19
Britbike forum member
Offline
Britbike forum member
Joined: May 2013
Posts: 6,686
Likes: 19
A decent set of points isn’t any easier or harder to start than a. Electronic ignition. A well setup set of points (no experience with triples) works as well as an EI, the only difference is once the EI is fitted it requires no adjustment or servicing.... that’s the only reason I switched.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: BSA C15 Won't Idle
kommando #803585 03/31/20 9:46 pm
Joined: Mar 2020
Posts: 6
Britbike forum member
OP Offline
Britbike forum member
Joined: Mar 2020
Posts: 6
I probably hold off on changing to an electric ignition, due to the time and cost. After looking at the distributor for a while, it seems the springs are in good condition, the condenser had some residue on it.

Im having trouble understanding how to set the ignition timing, spefically setting advance and retard, and the difference when when setting the btdc. This is my first time ever working on anything machinal, so i am a bit lost.

I also recently replaced the clutch, and messed around the alternator, but never removed the rotor. If this has anything to do with the issue.

I think I should probably try to set my ignition timing, before I go buying replacement parts?

Thanks everyone for the help!


smile
Re: BSA C15 Won't Idle
aidangoodmn #803589 03/31/20 10:17 pm
Joined: Sep 2013
Posts: 2,480
Likes: 20
Britbike forum member
Offline
Britbike forum member
Joined: Sep 2013
Posts: 2,480
Likes: 20
Quote
Im having trouble understanding how to set the ignition timing, spefically setting advance and retard, and the difference when when setting the btdc. This is my first time ever working on anything machinal, so i am a bit lost.

back in the day of distributors
the service manual may have given one BTDC down-hole piston-position ( or crankshaft degree )
for retard ( idle ) ... 1/16" ?
and a second for advance ... at 2000 to 3000 rpms... that will be somewhere is the 1/4" area.

... or just the retard position is given ... and the advance would be assumed by a correctly operating distributor .
re-reading the literature can help .

the distributor is a totally mechanical Advance device ...
so the 90° skew gear lag , distributor shaft bush size , counter weight smoothness of operation ( lubrication ) and spring strength
all play a part in it working reliably .


... the et ignition is timed differently ... does the bike have a battery ignition ? or ET ?
.

Last edited by quinten; 03/31/20 10:36 pm.
Re: BSA C15 Won't Idle
quinten #803593 03/31/20 11:24 pm
Joined: Mar 2020
Posts: 6
Britbike forum member
OP Offline
Britbike forum member
Joined: Mar 2020
Posts: 6
I am not exactly sure how to check if it is Et Ignition or battery? How would I go about figuring it out.

Would it be cheaper to replace the distributor with an electrex cdi unit, or go replacing the points and condenser, if those parts are the problem.


smile
Re: BSA C15 Won't Idle
aidangoodmn #803621 04/01/20 2:38 am
Joined: Sep 2013
Posts: 2,480
Likes: 20
Britbike forum member
Offline
Britbike forum member
Joined: Sep 2013
Posts: 2,480
Likes: 20
Originally Posted by aidangoodmn
I am not exactly sure how to check if it is Et Ignition or battery? How would I go about figuring it out.

Would it be cheaper to replace the distributor with an electrex cdi unit, or go replacing the points and condenser, if those parts are the problem.

the ET ignition does not have a battery or a rectifier ... it all A.C .
and there are 4 or 5 wires coming out of the stator . ..

the C15 had a long production run with a fair number of build variations .
until you get familiar with the nuances the workshop manuals can be confusing

Re: BSA C15 Won't Idle
quinten #803624 04/01/20 3:33 am
Joined: Mar 2020
Posts: 6
Britbike forum member
OP Offline
Britbike forum member
Joined: Mar 2020
Posts: 6
It is a battery ignition in that case, I have a battery and rectifier.


smile
Re: BSA C15 Won't Idle
aidangoodmn #803723 04/02/20 9:24 am
Joined: Feb 2006
Posts: 878
Likes: 1
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2006
Posts: 878
Likes: 1
Aidan, I had a C11 that would run like yours. It took ages to find the problem but it was the roll pin holding the gear on the distributor shaft to the gear itself. It was broken but would catch enough at idle to run well but when loaded up under acceleration the broken pin halves would let go and throw the timing off.

I don’t think that is your problem but it similar enough to make me think you should investigate the points and timing further.


'51 C11 in a '54 C10L frame. Back on the road...
'70 Triumph Trophy 500. Next on the bench for a refresh!
'72 Triumph Tiger 650. Back on the road...
Re: BSA C15 Won't Idle
aidangoodmn #803724 04/02/20 9:29 am
Joined: Feb 2006
Posts: 878
Likes: 1
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2006
Posts: 878
Likes: 1
....and I wouldn’t put electronic ignition on a Brit single like a C15 unless I was racing, or couldn’t get parts to fix it. Points will be the economical fix.


'51 C11 in a '54 C10L frame. Back on the road...
'70 Triumph Trophy 500. Next on the bench for a refresh!
'72 Triumph Tiger 650. Back on the road...
Re: BSA C15 Won't Idle
aidangoodmn #803725 04/02/20 9:46 am
Joined: Feb 2006
Posts: 878
Likes: 1
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2006
Posts: 878
Likes: 1
If you PM me I’ll scan and send you the pages from Pitmans book of the 250 BSA - 1954 to 1968. It is generic but does describe the ET ignition system, trials and scrambler and the road bike. It has the process for setting timing snd the TDC measurements.


'51 C11 in a '54 C10L frame. Back on the road...
'70 Triumph Trophy 500. Next on the bench for a refresh!
'72 Triumph Tiger 650. Back on the road...
Re: BSA C15 Won't Idle
aidangoodmn #803729 04/02/20 2:15 pm
Joined: Dec 2018
Posts: 107
Likes: 1
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2018
Posts: 107
Likes: 1
I cannot help but agree with those that say to stop messing about and fit electronic ignition. I know it is not "original" but the only reason BSA did not use it was that it hadn't been invented, as soon as it was, BSA's successor CCM fitted it ('72 or '73 as I recall).

Of course if you actually prefer messing about with an unreliable, maintenance heavy, obsolete bit of kit rather than riding the bike then ……….. wait ……. that kind of defines BSA ……. hmm …… maybe that is why I like them so much …… perhaps I should convert back to points!


Moderated by  Allan G, Jon W. Whitley 

Link Copied to Clipboard
Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | DVD- Manuals & Parts books
Upgrade to: Gold Membership | Premium Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.7.4