Big bore BSA B33

Catweasle said:

Good news the coil binding issue is finally solved!
I finally achieved it by lapping the valve seat in, removing some material from the retainers and then the spring it self.
Thanks everyone for their input
So onward to the next problem, the head bolts

Click to expand...

Hi buddy, love to hear updates on how your getting on with modifications, or did you get it going, mines still going pretty good, but need to replace my light switch, and I've just changed my oil, it's running sae50 with zddp, getting ready for summer. Cheers.

A bigger carb and a port job might be a backwards step, if you cannot rev it well up. With most single cylinder motors, it is better to make them pull rather than rev to gain power. A race cam usually gives nothing much under 4000 RPM. So what you have will probably not really go unless you rev it high. With BSAs the gearbox is a problem. An RRT2 gearbox has an extremely high first gear. But with a hot motor, you often need close ratios.

My, B33 has stock cams, but big valves, and porting is limited, otherwise the intake stub on the head would fall off, mine is a 600 cc and the delortto, is good no acceleration dead spots, I set the pumper to yield just a hint of black, on the road she's great very torquey, never a backfire. It revs enough for me, most of the mods to mine were done but, I had to fit a new piston, comp now 170 , replace and reset valve spring tension, get the top end oiling right. It's a good runner, I've just got my 49 matchless going, and want to go for a road test soon. Cheers