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How to adjust motor­cycle chain slack

Adjust­ing the ten­sion is bit involved, but is some­thing that needs to be done every once in a while or after repla­cing the rear wheel. Con­sult your owner’s manu­al for the exact amount of chain slack you need. I was work­ing on my 2006 Suzuki GZ250 which needs between 5 and 15 mil­li­meters of chain slack. A chain that is too tight can dam­age the sprock­ets or break at the worst pos­sible time. A chain that is too loose might slip off and end your ride.


1. Start by get­ting all the equip­ment you will need


You will need:

- a torque wrench
— a 12mm wrench
— a 17mm wrench
— a 19mm wrench
— a 19mm sock­et
— a hex key (I used a 5mm)
— a tape meas­ure (or some form of meas­ure­ment)

2. First, check your chain slack to see if it needs to be adjus­ted. If the slack is with­in spe­cific­a­tions do not both­er adjust­ing it.



You want to meas­ure the dis­tance from the top of the chain, when it is pushed down lightly, to the top of the chain, when it is pushed up lightly.



Take your meas­ure­ments from about the middle of the chain, halfway between the rear axle and the front sprock­et. Until you get used to visu­ally identi­fy­ing the amount of chain slack your motor­cycle needs, use a tape meas­ure to exactly meas­ure the amount of slack there is. The wear on a motor­cycle chain is going to be uneven. There­fore, the amount of chain slack will be dif­fer­ent on dif­fer­ent sec­tions of the chain. You want to take your meas­ure­ments at the spot where there is the least amount of slack. Turn the wheel and check the slack until you find the spot on the chain that has the least amount.

3. Using your 19mm wrench, loosen the rear axle nut.


This will take a little bit of elbow grease

You do not need to take the nut off. All you need to do is loosen it a couple of turns so the axle is free to move back­wards and for­wards.

4. Turn the chain adjuster nuts using the 12mm wrench to adjust the chain slack. To tight­en, turn the nut clock­wise. To loosen, turn the nut counter-clock­wise. Inside the swingarm is a little met­al block that the axle goes through which pulls the axle back or, when the adjuster nuts are loosened, allows the wheel to be pushed for­ward to cre­ate more chain slack.


Use quarter turns to be safe

Remem­ber, there are two chain adjuster nuts. One on the left and one on the right. They need to be adjus­ted equally in order to make sure the wheel stays in align­ment. Use quarter turns, altern­at­ing between each side in order to help ensure the wheel does not go out of align­ment.

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