Hi all, I finally got my BSA B40 on the road, so thought I would give it a trip around the lanes.
Above a certain revs, it sounded as if the crankshaft was leaving the engine. So when I got back after the 5 mile round trip, I inspected the engine mountain bolts... They were tight.
So I looked to see if it had a cylinder head steady... it doesn't, but noticed the tank was touching the 4 head bolts. I then adjusted the single tank mounting bolt to give 1/4 inch clearance to these bolts, and took it for another spin. This time the rumbling was not so great, but still there.
Back at the garage I noticed the centre bolt had a large washer under the nut, which was touching the metal of the tank. So I repositioned it to only bear on the rubber washer. I hope this fixes the crankshaft noises, but have not yet tried it down the road.
Will keep you informed of any cure.
Hi,
It is worth checking that you have all the correct tanks rubbers underneath. There are two located in the cross support near the front and one on the top of the frame at the rear of the tank. The tank sits on these with the centre bolt keeping it all in place.
Dave.
I would fit a head steady. Some years back I had a B40 which on a previous owner had removed the head steady. I recall it being a bit rough until I refitted it.