Motorcycles have two chains, one a drive chain which basically connects the output shaft of the gearbox to the rear wheel using sprockets. This drive chain transfers engine power from gears to rear wheel thereby putting the bike in motion.
There’s another chain inside the engine which connects the crankshaft to the rocker arms. It is also referred to as timing chain as it synchronizes the timing of the opening of inlet and exhaust valves during engine strokes.
A loose or a tight chain and worn out sprockets not only affects the power transmission but it can also lead to chain snapping i.e. breaking of the chain.
Chain maintenance at a high level involves
1. Cleaning the chain of dirt and old grease
2. Lubing the chain so that friction between chain and sprockets are not high
3. Adjusting the slackness or the play of the chain such that it’s within the manufacturer recommended limit
Lets first see what happens when the chain is loose
1. Creates unusual jarring noises when the chain runs over the sprockets
2. Chances of chain jumping out of the sprocket are high
3. Clanging movement of chain along with noise whenever the throttle is opened
4. Losing rollers on the inside of a chain
5. Quick wear of the O-rings (Bikes like Bajaj Dominar have O-rings, circular rubber rings between the side metal links)
What happens when the chain is too tight
1. Very high wear and tear of the sprockets and chain.
2. Chances of breaking the chain are very high, which may result in loss of rider and other parts as well
3. Reduced suspension travel length due to the high amount of tension in the chain
4. Power loss due to higher friction (though the amount is negligible)
5. Losing control over the motorcycle around the corners
6. Handling of the motorcycle is spoiled to a great extent
How to clean the chain
Motorcyclists, particularly grease monkeys are confused as to what sort of spray or liquid to use for cleaning the chain.
This video beautifully demonstrates different materials and their effectiveness in cleaning the chain.
How to lube the chain
Chain clean is not as frequent activity as lubing the chain. With lots of solutions in the market and their cryptic ingredients, it often becomes confusing to choose the most effective one.
I recommend to go through this video and look at the demonstration of different solutions available and their effectiveness.
How to adjust the chain slackness
It looks little confusing in the beginning to determine the right amount of slackness but once we know the fact good enough, adjusting the chain slackness is not that difficult.
Before moving on with adjusting the chains we should understand why does chain develops slackness and what can go wrong if we do not correct it.
Both chains (timing chain and drive chain) develop slackness. Why?
Its because chains are made of multiple small pieces connected with the help of links. Continuous running creates a gap between these and stretches the chain a bit, we call this enlargening of the chain, as slackness.
What’s the process to correct it?
Slackness of the timing chain is adjusted with the help of tensioner. The tensioner is a small mechanism fitted on the engine itself. Watch this video understand how it works.
Since it involves some complexity, I would recommend consulting a mechanic in case you feel your engine is making sound and a probable cause is timing chain slackness.
Adjusting the wheel chain is easier than the timing chain.
Adjusting the slack can be broken into two parts. 1. Identifying if there is slackness. 2. Fixing the slack.
Chain slack can be checked by placing a finger under the lower section of the hanging chain and observing the distance between the rest position and when its pushed to the top. Generally, the distance is considered okay between 1 cm to 1.5 cm but not more and less than that.
To fix the slackness, there’s a bolt in the rear wheel axel which needs to tighten. Over time this bolt will reach its limit, in that case, a couple of links are removed from the chain to reduce the chain length and installed again.
Here is a video showing how to adjust chain slackness.
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