in a motorcycle, what is a camshaft?

Answer 1

The camshaft is a necessary power consuming component of the four-stroke internal combustion engine. It is turned by a gear, chain or belt connected to the crankshaft. The camshaft lobes of an overhead valve (Harley V-Twin) engine push tappets and connecting rods up, which in turn swings the rocker arm that pushes down on the valve stem, opening the valve. The camshaft must be timed so that it opens the intake valve on the downstroke, closes both valves on the power stroke and then opens the exhaust valve on the next upstroke. The power lost in this process is substantial. That is why the valveless two-stroke engine is more efficient. It's poor emissions rating marked it for obsolescence. The overhead cam system in today's modern engines does reduce some the power loss by eliminating the tappet and push rod. The double overhead cam engine, which has 4 cams in the V configuration, is the most powerful because each shaft has a reduced load and is therefor easier to spin.

TD

Answer 2

Camshaft is a shaft with lobes that open and closes the valves in relation to the pistons. It is controlled by a timing belt or chain connecting to the crankshaft. Same as a car.

Answer 3

don't listen to TD, he just wants to confuse you. Camshafts are devices powered by hamster exercise wheels which produce the power necessary to propel the motorcycle. Thus, we have two wheel, four wheel and six wheel bikes. They are coupled to the exhaust manifold as the hamsters produce a lot of gas in the process, this propulsion method also explains the sound produced by most bikes.
EDIT: Annabella, mon cherie amour, why do you side with TD and allow him to confuse the young man asking this question. ? SHAME ON YOU !!!
DO NOT listen to Annabella, she comes from a country which foisted Citroen 2CV on the world (a "car" with bicycle tires and a canvas body.
EDIT2: aw, shucks, Annabella, I am just jealous of TD...
I have a bottle of Dom Perignon 1952 on ice, what do you say ?
EDIT3: OK, Anabella, you must be very French indeed to have a 2CV, I actually like that car very much, it does have a lot of character. I drove it a long time ago (from Paris to Barcelona) and must say only the French would have the cojones to put canvas seats in a car.. c'est magnifique!!!

Answer 4

Same thing it is in a car, only on a smaller scale usually. A rotating part of the engine with lobes on it that in turn pushes a rod that opens and closes the valves as needed.

Intake stroke, fuel air mixture introduced, intake valve open.
Compression stroke. Piston moves up, compressing the air fuel mix. Valves closed.
Power stroke. Spark plug fires, igniting the mixture which pushes the piston down. Valves closed.
Exhaust stroke. Piston move up, exhaust valve opens to let byproducts of the explosion into the exhaust system.

Repeat.

Answer 5

A friend of mine had this problem with a Honda 3 wheel ATV (anyone remember those?) It seems there is no bearing where the cam rides, just the aluminum head and "cam holder" (per Honda microfiche). Most engines are machined to accept replaceable bushings. Which is what my friend did! He took the head and cam holder to a machine shop with some bushing halves that had the right i.d., and they machined the head and holder to accept the o.d. of the bushings, as well as machined a flat on each end to accept the collar on the bushings. BY the way, 1981 (the year AFTER your bike) is when they came out with the 17 digit VIN.

Answer 6

camshafts are an old fashioned way to open the valves mechanically,they are then closed by powerfull springs resulting in considerable parasitic horsepower looses . they will soon be replaced with electrically operated solenoids directly controlled by the engine computer resulting in quieter more efficient & powerfull engines.

Answer 7

In an engine a cam shafts purpose is to open and close valves as is rotates in time with the crank shaft that moves the pistons up and down as it rotates

Answer 8

Here's a video of a camshaft in action. so you'll understand what it does and how it does it.

Answer 9

the cam shaft(s) in any engine actuate the valves by using an eliptical cam against the spring loaded valves.

Answer 10

same as in car or truck engine