29 replies to this topic

[Andy M]

I am gathering together the parts to build a Bantam trials to ride the BMCA trials,I have frame/engine and hubs, does anyone here have any pointers on what can be done with the frame, head angles or raising the engine etc.
Not sure what forks to go for, I won't be winning any medals out there but I want a rideable bike.

Up to now I know the gearbox mod to do, going for the 185 conversion from Rex Caunt, pvl or electrex cdi , 12 tooth g/box, f spkt and 60 r wheel.

Anything else worth considering, all info much appreciated.

Edited by bo drinker, 17 December 2010 - 01:09 PM.

[broony]

Bo Drinker,I'm in the middle of building Evo 2 Bantam at the moment.I have some drawings that I got from a member on this site which gives all the dimensions for dropping the top frame tube(bracing for the headstock),rear subframe mounting/subframe dimensions.Also swing arm mods.I've got a set of Suzuki GS125 forks/yokes(just cut off the lugs for the caliper-only £30 from the bay),Honda XL100 tank.If you P.M. me your e-mail address and home address I'll print some off and either e-mail them to you or pop them in the post.
cheers the noo Brian

[toyboy2]

Hi if you are looking at a 185 convertion try Mick Dickinson on 01709874956 for a barrel these have been made to suite trials abd not racing Garry Mitchel also has new gears the same as the works used. Garry can be got on 07766265766

[Andy M]

Thanks for replies. Any ideas which best way to go for the swing arm?? Mod the existing or go for a Cub arm ??

[B40RT]

bo drinker, on 18 December 2010 - 12:15 PM, said:

Thanks for replies. Any ideas which best way to go for the swing arm?? Mod the existing or go for a Cub arm ??

I thought Cub arms were a bit narrow as well ?

Have a look
http://www.trialscen...rear-swing-arm/

Edited by B40RT, 18 December 2010 - 12:40 PM.

[ferret1964]

Theres a chap who rides the BMCA trials, Steve Jones who has a company called progressive classics, he does frame/hub and swingarm mods for bantam trials and he is good.
Jim Pickering also rides with BMCA and he builds Bantam trials. also very good.

[broony]

Been doing a wee bit work on the Bantam and found out the following.Some of it is old information but it might help-starting with the frame:-the top tube can be lowered and the subframe mounting repositioned and the subframe narrowed/shortened.the swing arm can be extended by 1 inch(2 ways to do that extend at the slotted end(put in a fillet) or extend the tubes,if using an early (narrow) swingarm the right hand tube needs to be reshaped where the tyre/wheel runs for clearance.Front forks either standard heavyweight or fiddler type,rear shocks about 13" what you can afford(using road ones at the moment but even on there softest setting are a bit hard),Rims-front 21"xWM1 and rear 18"xWM2.Engine:- plenty can be done but its all down to the coin,with any two stroke a crank rebuid,big bore"don't laugh" the most common way to go is a Suzuki TS185 piston(standard =187cc,+2mm=198cc),the only prob is the small end is a different size(needs a bit of work),noticed that Rex Caunt does oversize pistons(big Bore).Todd head or later center plug head.Gearbox:- swapping second and third gears around makes the box close ratio,fitting a 12 tooth primary crank sprocket.Gearing 13 tooth front and 68 rear.Amal concentric with carb spacer/manifold and K and N style filter.Exhaust ,its recommended that the silencer has a volume of about 2litres and that it is close to the engine also that the exit is half the area off the inlet.Then you have various ignitions to choose from.Hope this is a help to fellow Bantam owners.
cheers the noo Brian

[Andy M]

Thanks Brian, that gives me a good start. PS I received the drawings you pm'd me. I will sort the engine first as it seems straight forward and then go from there.

[Monty_Jon]

Does anyone have a drawing for the frame modifications? (D7 type)

Also any idea where to get a cub wide swing-arm from? (failing this I will have to modifiy the standard one)

[Old trials fanatic]

Monty_Jon, on 26 January 2011 - 09:44 AM, said:

Does anyone have a drawing for the frame modifications? (D7 type)

Also any idea where to get a cub wide swing-arm from? (failing this I will have to modifiy the standard one)

Sammy Millers used to do a wide swing arm. Might be worth giving Richard a call to see if he has any left?

[Monty_Jon]

Old trials fanatic, on 26 January 2011 - 10:13 AM, said:

Sammy Millers used to do a wide swing arm. Might be worth giving Richard a call to see if he has any left?

I’m trying to build it on a tight budget (and on the quiet), as according to the missus I already have too many bikes!

So I’m trying to source second hand parts

Any frame & swing arm modifications would be greatly appreciated

[jamestee]

You could do no better than talk to Jim Pickering, mentioned already in a reply above, his tel is 07850 836571. He will be at Wrighty's show in Telford in a couple of weeks if you can get to it. I'm in the process of building up a Bantam courtesy of Jim P who provided me with most of the bits and I can highly recommend him as a real good lad, provides good gear and is very helpful.

[Andy M]

jamestee, on 26 January 2011 - 05:04 PM, said:

You could do no better than talk to Jim Pickering, mentioned already in a reply above, his tel is 07850 836571. He will be at Wrighty's show in Telford in a couple of weeks if you can get to it. I'm in the process of building up a Bantam courtesy of Jim P who provided me with most of the bits and I can highly recommend him as a real good lad, provides good gear and is very helpful.

Thanks, I will be going to Telford, there are a couple of localish people who are doing a lot with Bantams, Jim, and Rob Homer I hope to see them and pick their brains..

http://www.classicri...bantam-special/

[bilc0]

bo drinker, on 05 February 2011 - 12:26 PM, said:

http://www.classicri...bantam-special/

Very nice.

[Andy M]

Spent a few ££ and went for it. Frame sorted and powder coated since this pic,