Hi,
I have just acquired a 1968 Bearcat which is the ideal starting point to build  a Gaunt replica! Being the latest model of the Bearcat it has the B100 frame with the TC120 dual range motor it’s perfect for the job! But I have a number of questions...

Forks,
These should be from the Invader 200 are they still 30mm? And looking at photos they must be a bit longer if so how much? If I can’t find any Invader forks I’ll find something suitable that looks right 
While we are at the front did Peter alter the head angle?

Hubs
These look to be smaller than the B100 or Bearcat hubs, possibly  A100 or A50? 
Swinging Arm
I know it’s about an inch longer but does anyone know how much exactly? And what length shocks would be best?

Engine,
So far I’ll just be fitting the T20/ GT 250 piston as it needs a bit of a rebuild anyway 

Any information is welcome 

Thanks Ian

use the hubs from the K10/11 80cc Suzuki. I only have experience of using super six pistons, I think the GT250 ones are slightly shorter and may mess with the porting

Peter Gaunt used the Super Six piston, making capacity 128cc from 118cc.

There's a detailed article about the bike, including a picture of the lengthened swinging arm, on www.bsaotter.com in the article headed "Geekies Gizzmo" in the list on the right of the screen. 

Thanks I think the super six is the T20 and according to various websites the part number for the pistons are the same for the early GTs , but I will check again.

Ian

Just a piston update, I’ve gone for a Mitani 53.5mm B100 piston which is only 0.5mm less than the super 6 piston giving 125.8cc. I don’t think I’ll miss the missing 3 cc!

Ian