davet Posted June 16, 2015 Report Share Posted June 16, 2015 (edited) Can anyone advise me Sprocket size for bsa c15 trials . Thanks Edited June 16, 2015 by davet Quote Link to comment Share on other sites More sharing options...
bezaboy Posted June 16, 2015 Report Share Posted June 16, 2015 I run 18t on engine, 52t on clutch, 13t gearbox and 64t back wheel that gives me 14.4:1 Hope that helps. Quote Link to comment Share on other sites More sharing options...
davet Posted June 16, 2015 Author Report Share Posted June 16, 2015 Thanks bezaboy . Something to work with now , just bought it it's my 1st project . There maybe numerous questions to follow. Can you point me in direction for a new petrol tank ? Cheers Dave Quote Link to comment Share on other sites More sharing options...
bezaboy Posted June 16, 2015 Report Share Posted June 16, 2015 Dave, Try Terry Weedy, he does petrol and oil tanks and lots of other good bits. Quote Link to comment Share on other sites More sharing options...
mark447 Posted June 19, 2015 Report Share Posted June 19, 2015 I've just bought a c15 project trials bike. How do people get around the all in one brake drum/sprocket. On of the previous owners seems to have welded a sprocket onto the drum. not sure how effective this will be. Quote Link to comment Share on other sites More sharing options...
wallo Posted June 24, 2015 Report Share Posted June 24, 2015 All depends on what gears you have are they the wide ratio WD ones or standard road? Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted June 24, 2015 Report Share Posted June 24, 2015 I've just bought a c15 project trials bike. How do people get around the all in one brake drum/sprocket. On of the previous owners seems to have welded a sprocket onto the drum. not sure how effective this will be. Scrap the wheel and fit one from a cub or bantam. You could always fit a twinshock rear wheel off anything really but the purists would want you to use the cub or bantam option. Easy to change and get sprockets then. 2 Quote Link to comment Share on other sites More sharing options...
mark447 Posted June 24, 2015 Report Share Posted June 24, 2015 Cheers old trials, I've actually just bought a bantam rear wheel. Mark Quote Link to comment Share on other sites More sharing options...
mark447 Posted July 1, 2015 Report Share Posted July 1, 2015 Sorry for the lateness of this response Wallo, I haven't got a clue what's in the gearbox yet. By way of background , the guy I bought the bike from had owned it for 3 years (with the intention of restoring it), but hadn't done anything to it due to other projects. He bought it from the estate of the guy who'd taken it off the road, done some stuff to it, then popped his clogs taking it's secrets with him. Although I've ridden bikes for 40 years, this is my first Brit bike and first trials as well (it's very different to my old ZZR 1400 lol). Currently I'm trying to determine what I've got (see next post) and where to go with it. So now I've got a bantam rear hub, what sort of fettling does it require to fit to the C15, and what is the best size rear wheel to fit. Currently the back wheel is 4 00 17, but I've picked up that running a 4in rear can cause problems with the chain line . 1 Quote Link to comment Share on other sites More sharing options...
mark447 Posted July 1, 2015 Report Share Posted July 1, 2015 any idea what these front forks / hub are off Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted July 1, 2015 Report Share Posted July 1, 2015 Sorry for the lateness of this response Wallo, I haven't got a clue what's in the gearbox yet. By way of background , the guy I bought the bike from had owned it for 3 years (with the intention of restoring it), but hadn't done anything to it due to other projects. He bought it from the estate of the guy who'd taken it off the road, done some stuff to it, then popped his clogs taking it's secrets with him. Although I've ridden bikes for 40 years, this is my first Brit bike and first trials as well (it's very different to my old ZZR 1400 lol). Currently I'm trying to determine what I've got (see next post) and where to go with it. So now I've got a bantam rear hub, what sort of fettling does it require to fit to the C15, and what is the best size rear wheel to fit. Currently the back wheel is 4 00 17, but I've picked up that running a 4in rear can cause problems with the chain line . You have no choice you need to run a 4.00 x 18 rear tyre thats what is available so lace the hub to a suitable rim. WM2 or WM3 is up to you i use WM2 but there are people who would advise otherwise. Motor needs moving over in the frame 10mm at least some move further but then you have problems with the exhaust stub on the head fouling the frame downtube if you go too far. Once you have sorted the motor machine a ring to space the sprocket on the rear hub over the same amount. I went for 10 mm as a compromise. Use a 428 chain or if you dont mind changing frequently a 420. Miller apparently used a 420 on GOV to help with clearence so should be ok i used 428 btw and had no problems. A good guy to talk to is Charlie Prescott who now owns Bessie my old B40 which to all necessary features is the same as a C15. 1 Quote Link to comment Share on other sites More sharing options...
charlie prescott Posted July 1, 2015 Report Share Posted July 1, 2015 Hi Guy's. Hi Mark, You really need to widen that back hub you now have by 1 1/2" you can see how to do that on the "Otter' site along with a lot more info about a BSA C15. Regards Charlie. Quote Link to comment Share on other sites More sharing options...
mark447 Posted July 2, 2015 Report Share Posted July 2, 2015 Thanks for the info guys, you've both been a great help. Quote Link to comment Share on other sites More sharing options...
mark447 Posted July 4, 2015 Report Share Posted July 4, 2015 Apologies if I seem to have hi jacked this forum, I've just offered up the Bantam hub to the c15 rear swinging arm, to find the spindle on the hub is too big to go through the slot. do 1 a) machine the spindle smaller grind the slot wider c) none of the above (suggestions welcome) Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted July 4, 2015 Report Share Posted July 4, 2015 What dia is the spindle ? Has it been modified ? Modern practice is to use 17mm spindles so if that is the case modify the swingarm to suit. You could even weld on replacement slots which are available on e bay cheaply. 1 Quote Link to comment Share on other sites More sharing options...
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