Question about motorcycle clutch.

In the above picture, I don’t see how the clutch is disengaging the input shaft from the output shaft, because the primary drive still connects the engine to the input shaft which is constantly meshed with the output shaft. Does the gear of the primary drive on the input shaft spin freely or something and the clutch just locks it to the shaft?

It’s not obvious from that drawing, but what is happening is roughly as follows: The output from the engine (the green belt) is driving only one set of the clutch disks (say, the grey ones.) The other set of disks (the white ones) are connected to the tranny. Normaly, the spring on the end keeps all of the plates pressed together, and power flows from the engine to the transmission. When you pull the clutch lever, you take tension off of the spring and the plates simply slip past each other. IIRC one side of the clutch uses plates that are toothed in the center, causing them to spin with a shaft, and the other set of plates (every other one) has teeth on the OUTSIDE that lock onto a cylinder with slots cut into it. The cylinder and shaft then pass power when the plates are pressed together. I can never remember which side is attached to the engine and which to the tranny, though.

The clutch disengages the engine from the input shaft, not the input shaft from the output shaft. The input shaft is disengaged from the output shaft by the engagement dogs, which are fixed to the output shaft. The final gears “float” if they aren’t engaged by a dog (which is to say they remain engaged by the drive gears, but spin freely around the output shaft).

So does the gear on the input shaft that is connected via the belt to the engine spin independently of the input shaft when the clutch is disengaged?

I wouldn’t normally bump but I know that someone can help me with this.

It depends on the engine. On most of the bikes that I’m familiar with (IIRC), the “gear on the input shaft” is actually on the clutch basket, the outside shell of the clutch. The clutch hub, the inner part of the clutch, is attached to the input shaft.

So is that picture inaccurate? Because as it appears, there is a complete connection from engine to output shaft whether or not the clutch is engaged. At least it appears that way. The only way it could work is if the “gear” on the input shaft that spins the belt from the engine spun freely and somehow the clutch locked it to the input shaft.

The driven primary sprocket could be attached to the clutch by way of a sleeve that goes around the input shaft. That sort of setup would look like the giagram, but I suspect that it would be an unnecessarily complicated setup, would cost more to manufacture and wouldn’t be as strong.

giagram = diagram

Nothing useful to add here…

Just thought it was interesting that when I clicked on the link you provided, my company firewall blocked it – the reason was “Sex”.

The concepts of motorcycle clutch internals and nekkid chicks don’t sound like they go together, unless the pages also have lots of biker babes baring their boobs.

I guess I’ll just have to go there from home to see!

Well there is a guy oiling up a girl’s gearbox and working the input shaft pretty hard.
She’s got two shafts inside her already and a dog is trying to work it’s way into a hole too.