BSA TRACKER PROJECT..............................
Work commences on Odgie’s dirt-track scrambler. He begins with big bits from a BSA A65, adds a sprinkle of Triumph T140, Moto Morini and Can-Am components, and sets to with the welding kit…
Work commences on Odgie’s dirt-track scrambler. He begins with big bits from a BSA A65, adds a sprinkle of Triumph T140, Moto Morini and Can-Am components, and sets to with the welding kit…
My apologies if last month’s scene-setting was a trifle off piste, but rest assured we’re starting off in a good and proper classic vein this month. As I told you, we’re building a BSA A65 as a fast road bike / flat-track racer. The A65 has many good qualities. Far from being a simple unit construction continuation of the A10, which is how many people think of it, the A65 was very much a clean sheet. True it shares some similarities, the heritage is plain, but consider the differences. The most cursory of glances will tell you that while every other Britbike owner was fiddling with bent feeler gauges, A65 owners were setting their tappets with ease and aplomb.
When you dig deeper inside the A65, you find an engine that is a comparative joy to work on. Stripping and replacing the top end is a doddle compared to the endless pushrodjiggery-pokery involved with Triumph, Norton or the earlier A10. The gearbox is the cassette type, assembled outside the casing and then inserted complete – what price struggling with rulers and indexing marks now, eh? A triplex primary chain tells you the engine probably makes some power, and a quick peer down the inlet ports makes it immediately apparent why it does. No wonder they were all the rage in sidecar racing for so long, this is a welldesigned and constructed, powerful engine.
Of course, these days everyone prattles on about the bushed timing side main bearing. But answer me this; did we see endless A65s, or indeed A10s, or indeed 350 and 500 Triumphs stranded by the side of the road with blown bearings when they were in their heyday? Would BSA ever have considered carrying on with the same design if had any major inherent flaws? Of course not. A10s went to work and back every day and then went up and down the country on holiday with double-adult sidecars attached, year after year. A bearing-fed engine isn’t and wasn’t the anathema it has become, all the theories of centrifugal force and oil starvation fall into disrepute when you stop to consider that all car engines are fed their oil in exactly the same way.
No, what happened was… as British bikes fell down the food chain, as they become more worthless and more abused, as oil changes became less frequent, and maintenance fell by the wayside, they simply wore out. A worn oil pump, worn bearings, ancient oil, blocked sludge trap, not exactly surprising when the drive side big-end goes, is it? In all fairness, for highly tuned, high speed, racing motorcycle engines, a roller bearing is preferable for longevity. But every expert engineer I know thinks the same. If your mileage involves normal usage, just get the bush bottom end reamed and aligned properly and keep your £1500 plus in your pocket.
No, the main issue with the A65 isn’t with bearings, it’s with weight. A fully kitted A65 is over 30lb heavier than its contemporary Triumph counterpart. It’s weight you feel too. Just lifting an A65 off its sidestand and pushing it around makes the mass immediately apparent. And it isn’t just gross weight, but also weight relative to rider input that counts. Bear in mind that I’m a ten stone rider, so the heavier the bike, the effective less my body English will be at controlling a sliding motorcycle. So one of the main considerations in this build is going to be weight loss (the bike, not me, I religiously keep myself at ten stone for racing purposes).
We’re going to try and make it lighter. That may involve simple, cheap tricks like countersinking head bolts, and it will probably also involve rather more expensive but multifacetedly effective ones like alloy barrels for the engine (a 6kg weight loss in one fell swoop isn’t to be sniffed at, John Hill is the man to see here). But first, we have to make a start on the rolling chassis...