Chain tension help!

[UpcomingChris]

So i've tried to adjust my chain because it was too loose, But i've read that it should have 20mm slack, and somewhere else it says 30 - 40mm slack, it's a CG125 - 2000, and i'm unclear of how the slack is calculated, Would 20mm be 20mm from it's original position pushed down?, so 40mm slack from bottom to top, or does it mean 20mm from as high as you can push it, to as low as you can push it, if you understand?, Also should it be done on or off the centre-stand, because it gets alot tighter when you take it off the stand i found out

[Kickstart]

Hi

20mm would be the full amount (ie, from lowest position to highest position). Although that does seem a fairly small amount.

The amount varies between bikes. Mostly there to account for chain tension varying as the suspension compresses. Hence the angle of the swinging arm when unloaded and the distance from the swinging arm to the front sprocket makes a big difference to the amount of slack the chain requires.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[DMCpro]

remember to spin the wheel and keep feeling the chain, adjust it on the tightest point
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Honda CB-1, TS125X
VW Golf Estate

[numpty2]

Anywhere 20-40mm would be fine.
You are looking for the amount you can lift it up, halfway along the bottom length.
If the chain or sprockets are heavily worn, as you turn the wheel you might find a pronounced "tight spot", which is where the chain is tighter. In this case you might find that you have 20mm of movement in the tight spot, and 40mm of movement at the loosest spot.
Put it on the centre stand, as has been said.
Some people rotate the rear wheel in increments and check the tension every 2-3 inches. Some people just push the chain up with a finger, and then slowly rotate the rear wheel. The finger pushy technique does give you a dirty finger.

Too loose, and you might have the chain come off.
Too tight, and you can do serious bearing damage.

If in doubt, too loose is best, but it might be a bit of a jerky ride.

[UpcomingChris]

Thanks,

[numpty2]

This video clip speaks a thousand words:

https://www.youtube.com/watch?v=zB4DsHV8SAQ

One more thing, check the rear brake sensor is still right. If you more the wheel a long way you might find that the brake light is always on or always off.

[BanditMonster...]

A tip for you, if you have rod going to the break caliper losen the nut on the caliper so that can adjust when you are tighting or losening the tensioner.
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Derbi senda 50- Superbyke RMR 125 (chinese Suzuki rm)- Suzuki gs 500- Suzuki Bandit 600.