When accelerating in 2nd gear, especially when getting up to 4K rpm or higher the bike has the tendency to drop into neutral. The harder I accelerate the more likely this happens. This doesn’t happen in any other gear, any ideas what’s going on?
2nd gear is on the lay shaft. The end play of the layshaft is shimmed against the DS of the case. Per BSA, the end play should be "just perceptible". Shims are available in 3 thicknesses to tighten end play.
Shift fork can be bent, make sure fork is perpendicular to shift rod
If you have standard ratios (most likely), then 2nd and 3rd sliding gears are interchangeable. Swap layshaft and maishaft sliding gears. Unless someone has already saved the gearbox in the past with this trick! Check the dogs first.
The mating gear may be worn. If so find one that isn't.
When my bike did this it turned out to be a badly worn cam plate and plunger. The dogs are probably a bit worn on the sliding gear, I didnt replace it at the time, but did pay attention to the LS end float, it never jumped out after that.
Last edited by gavin eisler; 10/03/173:57 pm.
71 Devimead A65 750 56 Norbsa 68 Longstroke A65 Cagiva Raptor 650 MZ TS 250 The poster formerly known as Pod