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ALBANY VINTAGE & CLASSIC MOTORCYCLE CLUB

Colin WhiteProlonging the Life of Your Chain

By Colin White

THE final drive chain of your motorcycle seems a pretty simple and straightforward method of transmitting power to the rear wheel of your bike. It is however, a very efficient and economical means of propulsion. The design in fact is a piece of engineering genius.
Getting the maximum life for the money is important. The humble chain has been developed to take the awesome power that modern bikes are producing and a strong O-ring chain can cost you a packet. They are in a situation that exposes them to water, heat and abrasive material. These conditions often take their toll.
The two most important areas of maintenance are LUBRICATION and ADJUSTMENT.

Link diagramFIGURE 1. shows a sectional view of the components of the roller chain. The centre pin is the area most likely to be short on lubrication during the life of the chain. This is normally because lube is not directed onto the side plate allowing it to penetrate fully.

FIGURE 2. describes the reason that so many chains are not adjusted correctly. The final drive sprocket on most chain drive bikes is in front of the swinging arm pivot therefore scribing two different arcs. If not given enough slack or play in the unladen position the chain will be far too tight in the laden position when the sprocket centres and swinging arm pivot are lined up. A roller chain needs to be free of tension on the bottom run when being driven. This allows the lube to replace itself in the centre pin area ready for the next pull on the top run. If the tension is always there the lube just gets squeezed out.
Chain and swinging arm diagramCheck the adjustment when the rider, or rider and pillion are on the bike and adjust it to a minimum of 15mm of play at the tightest point. When the bike is on the stand it will be more than this. It is better to have the chain a little loose than a little too tight.

An over-tight chain also puts too much load on the final drive or output shaft bearing behind the sprocket.
With the modern "clean" O-ring chains there is a tendency to not lube them at all. They do require some roller to sprocket lubrication.
I have always thought that if you dont see a bit of gunk on the back wheel you're not looking after your chain. Shaft drive is the way to go if a squeaky clean bike is your thing.
Finally I would like to correct a typographical error I made in last issues TICKY TAPPETS. The inlet clearance on early Honda 4s is 1/4 of a turn NOT 1/2 a turn as I said. I hope this has not caused any inconvenience.

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