02-11-2019, 02:56 PM
With the bike idling in neutral, the crankshaft turns the clutch that rides on the mainshaft. The mainshaft has 1st gear machined into it, and the whole clutch and mainshaft/1st gear are all turning happily at around 665 rpm.
When the clutch lever (and RLET) are pulled in, oil friction between the clutch plates causes the mainshaft to continue to spin. Mainshaft 1st gear (12 tooth) is always meshed with the larger 1st gear (38 tooth) on the countershaft. (constant-mesh gearbox)
Because the rear wheel is not turning, the countershaft also is not turning. Countershaft 1st gear however, is spinning freely at around 210 rpm
When you put it in 1st, gear dogs splined to the stationary countershaft are forced sideways into matching slots on the side of countershaft 1st gear spinning at 210 rpm, locking that free-spinning gear to teh countershaft.
CLUNK!
Suddenly, both 1st gears, both shafts, and the inner clutch hub have to come to an abrupt halt.
That's why the clunk and lurch.
When the clutch lever (and RLET) are pulled in, oil friction between the clutch plates causes the mainshaft to continue to spin. Mainshaft 1st gear (12 tooth) is always meshed with the larger 1st gear (38 tooth) on the countershaft. (constant-mesh gearbox)
Because the rear wheel is not turning, the countershaft also is not turning. Countershaft 1st gear however, is spinning freely at around 210 rpm
When you put it in 1st, gear dogs splined to the stationary countershaft are forced sideways into matching slots on the side of countershaft 1st gear spinning at 210 rpm, locking that free-spinning gear to teh countershaft.
CLUNK!
Suddenly, both 1st gears, both shafts, and the inner clutch hub have to come to an abrupt halt.
That's why the clunk and lurch.