Tapered output shafts

[Michael Gilbert]

Hi all, I'm looking for a company that sells pulleys or sprockets for tapered driveshafts. Considering that a high percentage of the engines we use when converting a bike from petrol to diesel are equipped with tapered drive shafts, there seems to be nobody supplying them. The info on the tapers seems incomplete, the Ruggerini sales info says its a 1:5 taper, I don't know if this means one and a half degrees, one degree fifteen minutes or whether its one and a half mm per cm. As I have no way of accurately measuring this I cannot get a pulley or sprocket machined.
Somebody out there must have encountered and overcome this issue. Help !!!!!

[mark_in_manchester]

Wouldn't 1:5 imply 2mm reduction in diameter for 10mm axial travel along the shaft? I think you could measure this with a cheapo digi-vernier (measure over the full length of the taper to minimise errors, and perhaps cover the shaft in permanent marker and scratch index points with a sharp scriber), and get close enough to decide what to ask someone to machine for you. Chances are it will be a sensible 'round' number.

[Michael Gilbert]

I've found out that tapered shafts are only supposed to be used with constant speed applications, such as generators and compressors.
If I machine or have machined a taper on a belt drive pulley which is fairly soft I run the risk of the thing spinning on the taper.
The boss I'm using to mount the sprocket on is the remains of the gear which came with the engine. It is hardened steel and the taper has been precision ground, so I'm getting away with it.
I've decided to abandon the belt drive idea for the time being, as it would involve changing the crankshaft for a keyed parallel one and I CBA to do that.

[mark_in_manchester]

I might mention than MZ TS and ETZ 250s use a taper with no keyway on the (hardened) crank, onto which a mild steel female taper fits in the clutch centre. Contrary to what some detractors might suggest, this is not a constant speed application When they grip they're really hard to get off, but yes they can spin and pick up, which many MZ fans will have experienced - I have.