Several months ago I was given a Bultaco Model 3 Scrambler. This bike dated from about 1967. It was rough, but mostly complete, and I immediately began to use it as a parts bike for my Model 10 Sherpa T which I've been competing on for a couple of years in MAVT events. After a while it occurred to me that the frame was very similar to the Model 10, and the engine, which was in pretty good shape, could be made into a Trials engine by swapping the top end and a couple of the lower gears with Model 10 parts.
Now it would make a lot more sense to buy a Trials bike than to build one from almost any bike. In my previous efforts to build BSA Trials machines, it was easy to spend at least $1,500 to get the bike right, and this project would be no different. However, I get a lot of enjoyment from watching projects "grow" and I look forward to seeing this one become a real Trials machine
Sorry, no "before" photo. Here, the frame has had extra unwanted "bits" taken off and has received a coat of silver paint. The Model 3 rear rim was steel so it was replaced with an Alpina hub and rim I had laying around. The front end was rough and had a large hub and 19" rim, so it was replaced with a front end and wheel unit from another Alpina. I found them on ebay for around $100 including shipping. Though from a slightly later model Bultaco, it bolted right up. Front ends from Bultaco didn't change much for years. The swing arm was also replaced with a 1" shorter one from my "parts Alpina". Wheel base is now about 51 and 3/4 inches.
The engine is also shown here. Bottom ends of Trials and Scrambles machines were basically the same except for flywheel weight and gearing. I decide to stick with the lighter flywheel to see if the engine might be a little quicker off the bottom*. 1st and 2nd gears will be changed to Trials gears. The Trials top end is on the left (244cc) and the Scrambles top end is on the right (200cc)
* Bike actually is a little slower off the bottom due to other factors.
Footpegs are original equipment from a Model 10 Sherpa T. These actually came from my other bike. They were replaced by folding pegs, again from the Alpina parts bike. Not much grip here. The ends are bent slightly upward, just enough to hold your boot in place if things don't get too slippery.
I found these fenders on ebay. They are hand made of aluminum with a "rolled edge".
The pair cost me about $100. Though they are certainly subject to bending, plastic just doesn't come close for looks on an older bike.
The seat base is fiberglass, from Hugh's Bultaco. I was able to use the stock front bracket. The fender is used to support the rear. I have old foam in good shape, so I'm waiting on a seat cover.
IRC tires are inexpensive and work great. Very soft treads and flexible side wall. The pair cost me about $140 including shipping.
The bike had "spark" when I got it so I'm using the stock coil. The condenser has been moved from the magneto housing to a much cooler spot under the gas tank (on order). Most condenser problems seem to be a result of heat. Here, it is also easier to replace. It has a "bullet" connector to the coil wire and wire from the magneto.
Here its beginning to "take shape". Stock Model 3 fender brackets worked though meant for a 19" wheel. Rear fender had "tight curvature" so it was cut a little short in front. Mud flap will fill the area below it.
