Question re different types of primary drive and engine rotation direction

[willywombat64]

OK ..apologies if it sounds daft and unimportant but I have an interest in motorcycle mechanics having always done basic servicing and maintenance work on the various machines owned over the last 40 yrs but not much involving engine stripdowns . I like to understand things in depth and was thinking the other day about primary drives and a question popped up in my head that I haven’t been able to find an answer to so if anyone can help it would be appreciated.here we go !

I am aware the crankshaft generally drives the clutch outer either by 1/ a gear or 2/ a chain or belt. In the first case the clutch outer will spin in the opposite direction to the crank and in the second case the same direction .What i want to know is that if most gearboxes just have a mainshaft ( connected to the clutch ) and a countershaft (which eventually drives the front sprocket) it would mean that the rear drive chain would rotate in a different direction depending on the type of primary drive you have . Obviously the final drive chain always wants to be rotating in a direction so that the bike moves forward so how is this achieved with 2 different primary drive types? there is obviously something I don’t understand unless the crankshaft turns in a different direction depending on the type of primary drive or there is an extra gear involved . Hope you understand and sorry if I haven’t explained my question clearly but hopefully someone will understand and put me out of my misery! thanks in advance..Bill.

[bill_qaz]

Because the design of the gearbox defines the rotational direction of the output shaft.
Most have two pairs of gears engaged at any time when in gear so the output rotates in the same direction as the input.

[daveuprite]

Half of us have been riding backwards for years.

[Hugh]

Greetings Bill,

Might this sketch help you?

Direction of rotation.jpg (131.35 KiB) Viewed 3339 times

TTFN

Hugh.

[Hugh]

rotation.jpg (59.85 KiB) Viewed 3332 times

[daveuprite]

rotation.jpg

Beautifully explained.

[willywombat64]

thanks Hugh ..I can see it now ..for some reason I'd been thinking that the gear drive from the crank directly drove the clutch basket but it's the inclusion of an idler gear that makes the clutch basket turn the same way as if it had a chain driven primary drive .

[bill_qaz]

some do drive direct crank to clutch basket, no idler so contra rotation. Picture is Honda CRF 230.

The attachment crf 230 primary drive.jpg is no longer available

So gearbox input shaft is now turning opposite to crankshaft. The input shaft drives the output shaft via whichever gear is selected so now the output shaft is turning the same direction as the crankshaft.

crf 230 primary drive.jpg (72.3 KiB) Viewed 3307 times

[bill_qaz]

crf gearbox.jpg (65.06 KiB) Viewed 3305 times

[chunky butt]

Or a bit more confusing, clutch on the end of the crank, come my g450/ccm 450.......oops, sorry, I'll get me coat