Voge 300 Rally jumping out of gear: the checks before the gearbox

Owner reports rather than a manufacturer bulletin. A gearbox that jumps out of gear is more often being allowed to than failing, and the checks below cost nothing before the engine is opened.

The symptom

The gearbox is described as not very positive: shifts that do not feel definite, and a tendency to jump out of gear under load. It is most often reported among the lower gears, and when the shift has been made without conviction.

Why a gear jumps out

A gear is held by dogs, raised teeth on one gear that lock into recesses in its neighbour. When a shift is completed, the dogs engage to their full depth and the gear holds. When the shift stops short, they engage only partially, and under a change of load, on or off the throttle, the angled faces push them apart.

Every check below is about whether the shift reaches its full depth.

The clutch free play

The manual specifies 10 to 20 mm of free play at the end of the clutch lever, adjusted at the locknut on the clutch cable and, where the cable's range is insufficient, at the adjusting stud on the right-hand crankcase cover. It adds an instruction that bears directly on this complaint: after the engine is started, where clutch slip or difficulty in changing gear is felt, the adjustment is made again.

A clutch with too much free play does not fully disengage. The gearbox is then being shifted while still partly driven, the dogs meet under load, and the shift completes only part of its travel.

The service chart for the 300 series engine checks the clutch adjustment at every interval, and the friction plates at 5,000 and 15,000 km, which indicates how much the manufacturer expects it to move in service. The chart is set out in what Voge asks for at each service.

The chain

A chain that is too tight or too loose adds shock through the transmission every time the throttle is opened or closed, and that shock is what unseats a partially engaged gear.

The 300 Rally's manuals do not agree on the figure. The English edition asks for 30 to 40 mm in its procedure and prints 20 to 30 mm in its table; the French edition's text asks for 10 to 20 mm while its illustration shows 30 to 40 mm. The measurement is taken with the motorcycle on its side stand, as the manual describes, and the figure in the edition supplied with the motorcycle is the one to apply. The discrepancy and the method are set out in chain slack, adjustment and lubrication.

The gear lever

Neither edition documents an adjustable linkage on this model, so the checks are physical: the lever is examined for a bend after any drop, and for movement on its shaft. A lever that has been knocked upward or has slipped on its splines shortens the stroke a boot can deliver, and a shortened stroke is a partial shift.

The method the manual describes

The manual's gearbox instructions are brief and specific. With the clutch lever held firmly in, the selector is lifted for each upshift and pressed down for each downshift, with the engine speed allowed to fall before each change.

What this gearbox punishes is a half-hearted movement. A short, firm stroke all the way through, with the throttle closed and the clutch fully in, engages the dogs to their full depth.

When it is not adjustment

Where the motorcycle jumps out of one specific gear only, and does so consistently after the clutch, chain and lever have been checked, the cause is internal: worn dog faces or a bent selector fork. That is gearbox work, it does not improve with use, and each jump-out rounds the dogs further.

Related pages

The running-in requirements that protect a new gearbox are in running in a new Voge, and the remaining specification for this motorcycle on the 300 Rally model page.