Hi,New to this site done twin shock trials (badly) withTY175 but I recently bought a otter frame and wheels and a set of C15F cases and crank with alpha big end got a set of wide ratio gears from a b40 wd which I believe will fit in.considering putting a big bore barrel ie.triumph 500 piston any other suggestions or comments,will fit electics world ignition.

keep it simple..  ask yourself one question.. will doing this or that mean i will put my foot down less?

 

you can save a lot of time and money..

Are you mistaken by a 500 twin triumph piston? If so 1 of them is 250cc, used regularly in the bsa unit single.

As above keep it simple, and speak to Charlie Prescott. It will save you a lot of time and money

Loads on Charlies site.....

 

http://www.bsaotter.com/

Mine has a Triumph piston in it I think, gives it about 270cc. It came from a guy who advertises on eBay with unit single rebuilds etc. Good service from him and the rebored barrel and piston worked out almost the same as buying a piston and having mine bored. I've got the Electrex World ignition, expensive and needs a bit of tweaking to fit but works well and is a neat solution if you don't need lights.

Edited June 13, 201610 yr by japes1275

Hi,Thanks for all your suggestions.I do wasn't to keep it simple and CHEAP but I want to build and forget with reasonable and manageable performance so what cametc.long stroke or bigger bore.

I would keep it standard and see how you like it. I have a +40 Triumph 5TA unit piston in mine (70 mm I think), and it doesn't make a lot of difference to be honest. I always go for as low compression as I can, I usually skim a mil or two off the piston too. It depends on your skill level I suppose, but some pretty good riders ( not me !) find that that standard is enough.

Edit to ad, I use Electrex too, works fine for me

Edited June 15, 201610 yr by davetom

hi,i want to keep it simple and CHEAP but if you have to buy parts it must be cheaper to buy right part rather than fit later,i.e. cams, gears,sprockets etc.looked on otter sight very good.i like to put together and be happy and forget (never am)