Mythos
Registered
Proper chain tension is so vague as described in the SM. You search threads here and see comments like"always tighten on the sidestand", "I always use a rear stand," "a rear stand will make you over-tighten the chain," "better to tighten loose than tight," ... Many people seem to have different way of measuring proper chain tension and it seems to be okay. Sooner or later we find out what is right for us. In the end there seems to be definite do's and don'ts but the in between is left a little obscure.
I did a little test tonight and took notes. Thought some of you might be interested in reading the figures. This was done on my 08 Hayabusa with about 6000 miles on it. This was only the second time in the bike's life I felt the chain might need adjusting so I'm not sure I have it down perfectly yet.
The chain looked a little loose to me. Shifting is good except that it can be difficult to get the bike to downshift at very low speed. Sometimes necessary to partially release clutch lever to get it to go into gear or sometimes need to roll the bike forward at a standstill to get the shifter to click down.
These are the measurements I took for chain slack before, during and after the chain adustment I did. Bare in mind, I am using hand pressure to determine tension and this is pretty subjective and not totally consistent. I was very careful though, checking and rechecking.
Bike on sidestand, measurement taken where the chain happened to be positioned, no particular tight spot or loose spot in the chain was sought out. It was probably positioned at a tight spot.
Bike up on rear stand, wheel rotated to loosest spot in chain.
Bike on rear stand, wheel same position as last, axle nut loosened up.
Bike on rear stand, chain was not moved from loosest point, axle nut still loose. Chain tensioner bolts turned out (tightening chain) one-sixth of a turn (one flat, ONLY) on each side.
Bike on rear stand, wheel still at loose spot in chain, axle nut torqued, after adjustment mentioned above.
Bike on sidestand, wheel at loose spot in chain, after adjustment.
Bike rolled across floor so chain was positioned at the spot where I first checked chain tension, this is after the chain tension adjustment of 1/6 turn on each adjuster was completed.
My conclusions are these:
1. Measure chain slack with the bike on the sidestand. It is ~3/4" tighter when lifted on a rear stand.
2. Not all bikes may have a tight spot in the chain but if it's like mine, you really want to find it before you make the adjustment. Otherwise, you should probably go for the max 1.2" tension where ever you have the chain positioned.
3. Tightening the axle nut causes a 1/8" increase in chain tension in addition to the adjustment bolts.
4. 1/6 of a turn on the adjuster bolts + tightening the axle nut causes the chain to be a total 1/4" tighter than it was before the adjustment which is usually plenty unless your chain was very loose.
5. There can be a 1/4' difference between the loosest spot in the chain and the tightest spot in the chain.
All thoughts welcome. I have not ridden the bike yet to feel if the shifting has improved or any other changes. Visually, the chain looks to be a good tension to me, drooping a bit but not swooping down from the sprocket and laying excessively low.
I did a little test tonight and took notes. Thought some of you might be interested in reading the figures. This was done on my 08 Hayabusa with about 6000 miles on it. This was only the second time in the bike's life I felt the chain might need adjusting so I'm not sure I have it down perfectly yet.
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The chain looked a little loose to me. Shifting is good except that it can be difficult to get the bike to downshift at very low speed. Sometimes necessary to partially release clutch lever to get it to go into gear or sometimes need to roll the bike forward at a standstill to get the shifter to click down.
These are the measurements I took for chain slack before, during and after the chain adustment I did. Bare in mind, I am using hand pressure to determine tension and this is pretty subjective and not totally consistent. I was very careful though, checking and rechecking.
Bike on sidestand, measurement taken where the chain happened to be positioned, no particular tight spot or loose spot in the chain was sought out. It was probably positioned at a tight spot.
1 1/8”
that would be almost as loose as it should ever be according to the SM's .8"~1.2" spec if you measure the chain slack with the bike on the sidestand. The SM seems to be suggesting the chain tension be measured with the bike on a "jack", not the sidestand. Bike up on rear stand, wheel rotated to loosest spot in chain.
1 3/4”- 1 7/8”
Bike on rear stand, wheel same position as last, axle nut loosened up.
1 3/4” about the same as with the axle nut tight.
Bike on rear stand, chain was not moved from loosest point, axle nut still loose. Chain tensioner bolts turned out (tightening chain) one-sixth of a turn (one flat, ONLY) on each side.
1 5/8” the chain has been made 1/8" tighter than the last measurement with just 1/6 turn of adjusters on both sides.
Bike on rear stand, wheel still at loose spot in chain, axle nut torqued, after adjustment mentioned above.
1 1/2” The chain is about 1/4 inch tighter now that the axle nut has been tightened as it was when the first measurement on the rear stand was taken.
Bike on sidestand, wheel at loose spot in chain, after adjustment.
1 1/8” just a hair tighter than the loosest specced tension.
Bike rolled across floor so chain was positioned at the spot where I first checked chain tension, this is after the chain tension adjustment of 1/6 turn on each adjuster was completed.
7/8”This is just a hair looser than .8 inch which is the max tension that the drive chain should be set at /Service Manual spec.
My conclusions are these:
1. Measure chain slack with the bike on the sidestand. It is ~3/4" tighter when lifted on a rear stand.
2. Not all bikes may have a tight spot in the chain but if it's like mine, you really want to find it before you make the adjustment. Otherwise, you should probably go for the max 1.2" tension where ever you have the chain positioned.
3. Tightening the axle nut causes a 1/8" increase in chain tension in addition to the adjustment bolts.
4. 1/6 of a turn on the adjuster bolts + tightening the axle nut causes the chain to be a total 1/4" tighter than it was before the adjustment which is usually plenty unless your chain was very loose.
5. There can be a 1/4' difference between the loosest spot in the chain and the tightest spot in the chain.
All thoughts welcome. I have not ridden the bike yet to feel if the shifting has improved or any other changes. Visually, the chain looks to be a good tension to me, drooping a bit but not swooping down from the sprocket and laying excessively low.