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Author Topic: TUNING MY C11  (Read 522 times)

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« on: December 01, 2008, 11:13:47 AM »

From: Birchy  (Original Message) Sent: 06/03/2008 09:37
G,day all
just need a easy and quick guide to tune my BSA c11,1953 OHV
reason for this is that it pops on idle,changes speed on idle and is a bugger to start hot.
sounds like gun fire in the shed if started hot and it backfires out the exhaust,very spectular fire ball,wife comes down hopeing i have shot myself
 my Dog already has a burnt bum and thinks its been shot in the date.
Re the timing,is there an easy way,at the moment it is done by turning the distributor to where it runs  nicely,or do u have to set it 1/32" BTC,its a bugger to measure and guess if the points are openning, any easy to make guages???
Carbie is an Amal 626/300
jet size 160
clip on needle at the top,leanesti
dle about 1.25 turns out
i know its not an original carbie,came with the bike
both valves set to 3 thou cold
any quick usefull tips would help
you blokes probally have done a tune up a million times,some of you could do it in the dark
any help would be appreciated
best regards

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From: sergentwoodie1 Sent: 06/03/2008 12:57
Timing as you say 1/32" BTDC or near as dam it TDC Gauge purchase pack of Rizla roll up fag papers place one sheet between points bring it up to top dead centre
Points should just release paper at 1/32".
Plug Champion L10s or equiverlent
Carb should be 25/32 ventura
80 main
4/4 slide
Needle third from the top with 4 slots
.1055 jet
start at one & half turns out
Tappets correct unless you have later camshaft fitted which is 29-2079 the should be 10 in 12 ex

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From: sergentwoodie1 Sent: 06/03/2008 13:01
Sorry cut myself off very painful. My Dog has'nt spoken to me for weeks with the Bantam . SWMBO has'nt since  VE day 1945!  Best O luck Take care Woodie

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From: Birchy Sent: 07/03/2008 10:07
Thanks for the reply Woodie
already started checking settings
its a bugger measuring 1/32",might have to make a gauge but i think i have it close
will take it for a test ride tomorrow
checked plug and ok,points OK
carbie is a dogs dinner
dont know how the two relate,jet size,needle,pilot size
but will check plug condition
seamed to start ok hot and cold after setting timing
no fire balls and the dogs are happy but wary,all had a quick dash to the door when i kicked it over
best regards

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From: camman3 Sent: 07/03/2008 10:49
Hi Birchy,
I have foun the best way to do timing is firstly connecting a continuity test buzzer between the pionts lead and ground. When buzzer stops the points have just opened, better with buzzer than bulb as you can concentrate on piston position. put a rod down plug hole and bring to TDC, make corresponding marks on rod and head, make another mark 1/32  up the rod, turn crank round to firing position i.e. with second mark on rod in line with mark on head, the buzzer should stop just as you come to this mark, if not, advance or retard points, and bring round again.
For the sake of your dogs sanity, and your engine, it pays to get this fairly accurate, but my guess is more of your problems are the carb, probably be a good idea to see if you can get the correct one.
I got charged at by a 13 stone pig who didn't like the sound of my C12, so scaring the dogs is safe enough, look upon it as a training exercise for them!
Happy riding

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From: PeteRudge1 Sent: 07/03/2008 17:23
I use a plastic drinking straw rather than anything solid to mark tdc, it's easy to mark with a pencil and won't cause any damage should the piston come up quicker than expected.

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From: camman3 Sent: 08/03/2008 21:41
Yes I agree Pete about using straw or soft material at least. I always try to do ignition timing when the priamary chaincase is off, when you can bring the piston up nice and slowly with a socket directly on end of crankshaft, difficult to control by turning wheel even when in high gear.
How are you all?
I've been away for a while.....all sorts of ongoing problems that I wont bore you with, hope to be on an even  keel in the next couple of weeks, so I can relax and get ready for the great Spring Run!
Haven't forgotten about your clutch spacers by the way, just haven't had a moment, sorry.
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