question {Belt final drives} - Motorcycle-Journal Forums

cowboyup75146 · 10-22-2007, 09:54 PM

On certian bikes [ harley, customs. etc] there is a belt on the left side coming from the engine going back to the tranny.
Question is,why do some have this? . Why Don't meteric mc's have this?
Why are some built into the eng. [ Yamaha-honda -kawsaki-suzuki]????
Thanks

wookie · 10-22-2007, 10:52 PM

If you are talking about what I think you're talking about, you're referring to the belt that connects from the engine/transmission combo (sorry for the lack of a better term) to the "round thingy" co-axial to the rear wheel.

If that's the case, then that's the driving belt that transfer torque/power from the final output gear of the transmission to the rear wheel "sprocket" (to the gurus, what is the proper terminology).

Some bikes uses belt-drive others uses shaft drive. I think that's what you've observed....

**inspiron** · 10-23-2007, 03:17 AM

I think what you are talking about is the "primary drive" belt, which connects the camshaft and the transmission on the V-twin bikes. On many choppers, this primary drive is a wide (3" - 4" belt), often open and visible.

This mechanism isn't needed on other bikes or is encased in the motor block. Some engines have the camshaft placed front-to-back (BMW's boxer, MotoGuzzi V-twin, etc.) or use gears or a chain to convert the transverse rotation of the camshaft directly to the clutch plates, which are also integrated into the motor (and included in the oil circulation to keep them cool).

Take a look here for some drawings of BMW 1- and 2-cylinder engines to see how it's done.

JmalB · 10-23-2007, 05:39 AM

I think it's a style thing to have it on display like that. /shrug

**Clint** · 10-23-2007, 07:04 AM

That would be the "crankshaft", inspiron, not the camshaft. I'm sure it was a slip of the tongue.

**inspiron** · 10-23-2007, 07:10 AM

Quote:

Originally Posted by RowdyRed94

That would be the "crankshaft", inspiron, not the camshaft. I'm sure it was a slip of the tongue.

Actually, more like a brain fart.

You're right, Rowdy, I meant crankshaft.

I had a bit of translation problem between "Nockenwelle" (camshaft) and "Kurbelwelle" (crankshaft).

10-22-2007, 09:54 PM	#1 (permalink)
cowboyup75146 Seat Tester Joined: Dec 2006 Bike: 06 yamaha roadstar Location: Lancaster, TX Posts: 80	question {Belt final drives} On certian bikes [ harley, customs. etc] there is a belt on the left side coming from the engine going back to the tranny. Question is,why do some have this? . Why Don't meteric mc's have this? Why are some built into the eng. [ Yamaha-honda -kawsaki-suzuki]???? Thanks

10-22-2007, 10:52 PM	#2 (permalink)
wookie U.B's LoveChild Joined: Apr 2005 Bike: '05 SV650S; '05 GSX-R600;'04 749S Location: 20 Miles East of LA Posts: 1,235	If you are talking about what I think you're talking about, you're referring to the belt that connects from the engine/transmission combo (sorry for the lack of a better term) to the "round thingy" co-axial to the rear wheel. If that's the case, then that's the driving belt that transfer torque/power from the final output gear of the transmission to the rear wheel "sprocket" (to the gurus, what is the proper terminology). Some bikes uses belt-drive others uses shaft drive. I think that's what you've observed.... __________________ "Don't wrestle with pigs. You both get dirty and the pigs love it." "Don't argue with idiots. They will drag you down to their level and then beat you with experience." "The Universe is a contest between engineers making things idiot-proof and God making bigger idiots. So far, God is winning by a wide margin."

10-23-2007, 03:17 AM	#3 (permalink)
inspiron Muscle Biker Joined: Jul 2004 Bike: Blue Suzuki GSX 1400 (2003) Location: Canton Basel-Land, Switzerland (47.4493, 7.76536) Posts: 11,947	I think what you are talking about is the "primary drive" belt, which connects the camshaft and the transmission on the V-twin bikes. On many choppers, this primary drive is a wide (3" - 4" belt), often open and visible. This mechanism isn't needed on other bikes or is encased in the motor block. Some engines have the camshaft placed front-to-back (BMW's boxer, MotoGuzzi V-twin, etc.) or use gears or a chain to convert the transverse rotation of the camshaft directly to the clutch plates, which are also integrated into the motor (and included in the oil circulation to keep them cool). Take a look here for some drawings of BMW 1- and 2-cylinder engines to see how it's done. __________________ There is nothing worse than aggressive stupidity. - Johann Wolfgang von Goethe blog: gsx1400

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