SMALL STAR
I enjoyed Rowena’s article on the BSA 250. I have used this model to compete in New England enduros and AHRMA road races. The weakest point is the shell plain bearing lower end. BSA-Triumph fitted the 1971 250s with oil filters in order to keep the bearings clean and the engine running. In practice, success varies. I lost the engine twice on my enduro bike, a failure rate I have not had with any other dirt machine in 50 years of trail riding. Perhaps I didn’t keep it revving high enough, which some people recommend as the solution.
Lower end failure was a chronic problem on the road racer until a change to a Nourish crank with needle bearings. I am quite sure I revved that bike high enough. Even so, one memorable engine seizure, accompanied by a lurid fishtail and a cloud of smoke, in top gear at full throttle on the front straight at Steamboat Springs, elicited a communal gasp from the grandstand, easily heard over the sudden silence. Luckily, the machine was kind enough to respond to a quick pull of the clutch lever, and we neatly coasted to the paddock without assistance.
My enduro bike had been punched to 280cc with a kit sold by the US BSA-Triumph distributor. Other mods were made to replicate the 1973 TR5T ISDT bikes as best I could. My efforts to waterproof the bike paid off, especially the quick access airbox / electrics protective skirt I fashioned. The best moment on the trail had to be a 50 yard wide, tankdeep river crossing. As the T25 motored its way across without so much as a burp, I was fairly amazed. When I arrived at the opposite bank, I found it littered with idle bikes and frustrated riders, in itself a short, but worthy observed trials section. (Only one New England Trail Riders Association enduro is required to teach a neophyte how to ride in the mud, believe me. Just as one desert enduro is sufficient to learn how to ride sandwashes. ‘Sink or swim,’ we all know the drill).
I used the large conical front brake quite a bit road racing a B25 and a B50. Set up correctly, they work very well, to a point. The drum needs to be machined round to start. However, the heat generated in competition tends to distort the cone and brake liner so it’s round no longer. Although the shoes are easily adjusted for wear through a small access hole, it’s a losing battle. But for normal use, the issue becomes minor.
Both the B50 and B25 are good machines (the former, most excellent, in my opinion), and well fit for a variety of purposes. On a road course or long MX track, there is room for an amateur to use the extra power of the 500 to good effect. But on a technical enduro trail, the 250 is better suited because of its lower weight, as long as you can keep it running.
I’d recommend the T model’s alloy petrol tank if you switch from the large steel. The flip top cap may take extra care at the pump, but the weight reduction and rust elimination are pluses, to say nothing of the look of polished aluminium. I have seen pics of a unicorn, a T type alloy tank with the large SS half turn type cap, but only ever one.
Kudos to you both for keeping your 250s on the road. And many thanks for all the RealClassic issues. Paul F Shoen, member
This is all extremely encouraging. We’re definitely going the slimline petrol tank route and will be collecting the freshly-painted spare tank later this month. You’ll read all about Frank’s endeavours with the front brake in The Shed, no doubt! Rowena