I started working on the Trials bike yesterday morning, and made pretty good progress. I decided to see if I could beef-up the original frame. As it happens, the ID of the main downtube is roughly 1.68". The OD of a piece of Schedule 40 steel pipe is 1.6", and has a much thicker wall thickness. So I cleaned up the ends of the downtube, cut a section of the schedule 40 pipe, and persuaded it inside the downtube with the help of a 5# sledge and some cussing. I plug welded the steel pipe in 20 different places before seem welding the downtube pipe back in place. I also added a thin brace on the underside of the downtube, using a piece of 1/4" thick, 3/4" wide strap material. I can't imagine the frame is going to break again.
Another project I wanted to work through was to see if a telescopic front end from a Honda CL90/S90 would mount up. As luck would have it, all of these small old Hondas use the same size steering stem and steering bearings, so the CL90 front end bolted right in place.
The stock setup was the old leading link system, which had a 14" distance when measured from the lower bearing race to the center of the front axle. I had made up a set of lengthened leading links that made that distance 18". This setup has been working fine, but it was another small non-stock part that could cause problems. The CL90 telescopic front end also had an 18" distance, so I had the ride height I wanted.
The only "issue" I had with the front end swap, was that the CL90 front axle was bigger in diameter, and wouldn't fit through the hub/bearings on the C100 wheel setup. As luck would have it, one of the CL90 parts bikes had what looked like brand spankin new 2.75"x18" trials tires mounted front and rear. So I grabbed the front setup, gave it a good cleaning, and mounted it up. That netted me another 1/2" of ride height up front since the original wheel was 17" diameter.
Today I got the freshly painted chassis, front end, rear end, engine, wiring, fuel tank, and exhaust all mounted up. I need to order a new chain, as the old nasty chain that was on the bike broke apart during my pile drive move.
Random pics below.