So, you think you know how to tighten your chain, do you?

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.

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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.
 
Now that's interesting!! I didn't know that,
I tried that method on my previous CBR and chain slack was the same either on kickstand and on wheel stand.
Is it because CBR is almost 200 lbs lighter and when lifter on stands does not press on swing arm as much??
My Busa is still new, I have only put 300 miles on it.
What is the axle size nut and how much need to be torqued?
 
I always go to the loose side. Some reasons why, as the swingarm pivots through it's arc the chain will get tighter than when you are measuring it, a tight chain will load the suspension and a tight chain will pull on the bearings at each end of it unduly. IMO
 
Krap, now you made me paranoid. When I did a rear sprocket swap, did the 1st chain slack measurement when bike was up on rear stand. Then compared that when bike was on sidestand. Pretty darn close to the .8-1.2 range listed in the manual.
 
Running the chain too tight can cause this:

Loose Bearings closeup.jpg
 
I'm curious how everyone measures the slack. From hanging "naturally" to as far up as you can easily push it, or from as far down as you can easily push it to as far up?
 
After owning a touring bike with a shaft drive for many years the maintenace required on a chain drive bike suprised me ah well the busa is worth it :thumbsup:
 
I tried that method on my previous CBR and chain slack was the same either on kickstand and on wheel stand.
Is it because CBR is almost 200 lbs lighter and when lifter on stands does not press on swing arm as much??

That would be my guess too. Also possibly stiffer suspension.


What is the axle size nut and how much need to be torqued?

36mm socket and torqued to 72.5 ft lbs.

I always go to the loose side. Some reasons why, as the swingarm pivots through it's arc the chain will get tighter than when you are measuring it, a tight chain will load the suspension and a tight chain will pull on the bearings at each end of it unduly. IMO
Same here. I don't have a problem riding with the chain a little loose. It actually gets tighter at high speed from centrifugal force. A chain would have to be pretty loose to actually fall off. I have noticed that proper chain tension makes a difference in gear shift quality and smoothness between on / off throttle. Too loose of a chain will make my ZX-14 miss shifts sometimes and it can get to the point that it feels a little jerky on/off throttle.

Krap, now you made me paranoid. When I did a rear sprocket swap, did the 1st chain slack measurement when bike was up on rear stand. Then compared that when bike was on sidestand. Pretty darn close to the .8-1.2 range listed in the manual. Aw, heck, Kromdome, you know what you're doing. If it the chain slack was in spec as you mentioned, I'm sure it's just fine.

Running the chain too tight can cause this
ugh! better than snapping a chain though. I have actually never heard anyone say that happened to them. They stretch out pretty quick which reduces the duty life and I guess possibly cause bearing damage.
 
I'm curious how everyone measures the slack. From hanging "naturally" to as far up as you can easily push it, or from as far down as you can easily push it to as far up?

I am assuming we are still discussing chains right? :lol:
It's easy on the busa. I lay on the floor and hold a steel ruler with eighth inch increments at the center of the bottom run of the chain. The front screw of the chain guard is a good reference point for right about smack in the middle. Basically you need to pull down and measure, then push up and measure. Add both measurements together and you have your chain slack.

Try to find the tight spot (if there is one) in the chain before you take your measurements. Roll the tire a little at a time and lift up on the top run noting where your hand seems to lift the least. That is very hard to do without lifting the bike on a rear stand but when you find the tight spot, you can take the bike off the rear stand and place it on its sidestand to measure the slack.

If you don't have a rear stand, it probably is fine to do the measuring at three equal distant points on the chain and average them.

Line up any even inch mark on the ruler with the the bottom of the chain. It doesn't matter which mark, 4, 6, 3, anything, just as long as you can see it and know that is where the bottom of the chain is located at rest. Hold the ruler steady and pull down about two pounds of force and note how many eighths / inch the chain traveled. If you want to recheck it, push UP on the chain about two pounds pressure first, line up your even inch mark, pull down as you did before and retake the measurement. Repeat that same process pushing up for the second measurement. You can take both measurements from the bottom edge of the chain or if it's easier to see, you can take one or both from the top edge of the chain. You are not worried about measuring the thickness of the chain, you are measuring how far the chain travels down and then up and adding the two together. You could even use the top run to measure the chain slack but I believe the chain will hit the chain guide on the swingarm before you could press down the two pounds of pressure.

That's the way I do it and if you're going by the .8~1.2 spec, seems to me it should be done with both wheels on the ground and the weight of the bike on the suspension-- or on the sidestand.

If you adjust the chain with the bike on the sidestand, make sure it can't roll forward AT ALL when you tighten the axle nut or the sidestand will fold up and the bike will fall.
 
After owning a touring bike with a shaft drive for many years the maintenace required on a chain drive bike suprised me ah well the busa is worth it :thumbsup:

+1, I don't want to see a busa with shaft drive. It eats a few hp more than a chain and it's heavy. That's not for this kind of bike.
 
Nice write up. Always wondered if I was doing it right. I just measure while on the side stand. Stay in closer to the 1.2 range. Don't torque up hard on the chain while measuring. Just use one finger and give some nice even pressure. Sounds like that is the common and acceptable method. Now I can sleep tonight. :laugh:
 
Sounds like a good method to me and exactly what I have been doing up to this point on my other bike. I just wanted to know what the differences in measurement were by using a rear stand, with the axle nut loose, tight spot, loose spot, etc.

If anyone really wants to know what absolute proper tension is, ratchet some straps across the seat and compress the rear shock to full compression. Look at chain. Should be tight like a rubber band. There should be some slack in the chain all the way up to this point. That would be perfect chain tension for the entire range of the rear suspension but I'm not quite that much of a nit-picker that I'm going to try it. :laugh:
 
Something that I do is loosen the TQ arm for the rear brake caliper. You mention that you see an increase in tightening when torquing the axle nut; in my experience (for what that is worth) the tightening is uneven in that even because the TQ changes the rear wheel alignment ever so slightly. In order to avoid this, I loosen the TQ arm bolt at the caliper and re TQ it, after I have TQ's the axle nut. This may be completely nuts and unnecessary, but it is how I have done ever since the first time I couldn't figure out the irregular wear on the rear sprocket due to mis alignment.
 
I've tightened the chain many times on my other bike and always noticed that the tension in the chain increased after the axle nut was torqued. Someone suggested that it was because the swingarm legs get pulled toether a tiny bit, lengthening the wheel base ever so slightly.

I believe that the axle may get cocked a tiny bit from torquing the axle nut. All the force is on on the right side where the axle nut is. One thing I do to maintain a straight axle is to make sure I am lifting on the wrench when I tighten the axle rather than pushing down. If the axle nut is on the right side and you lift, you're pulling the axle forward in the blocks and pulling teh blocks against the adjuster bolts. Hopefully everything pulls forward nice and tight on both sides.
 
This was posted at cbrxx.com 8 years ago. It's the guideline that I used for almost 70,000 miles with my Blackbird and am currently using on my Hayabusa.

The measurement that Mythos found when the bike is on a rear stand, seems to be about what's mentioned in this old posting.

"First of all, I use a technique that I learned several years ago from a gentleman who knew much more than I when it came to working on your bike ("Pops" Yoshimura). The technique described here works great on the 929 or any other bike that has the same overall swingarm length when measured from the center of the swingarm pivot bolt to the end of the swing arm.

Step 1

Put the bike up on the rear stand and clean the area around the rear axle and chain adjusters. Loosen the rear axle nut until it is loose enough to move the axle in the swingarm slots by moving the rear wheel/tire.

Step 2

From the rear of the bike, grab the rear wheel and pull it back away from the engine. Sight down the chain to make certain the chain is approximately straight.
Loosen the chain adjuster lock nuts.

Step 3

On the chain (left) side of the bike, using one 12 mm open end wrench, turn the chain adjuster bolt (the one toward the rear) counter clockwise until the chain has approximately 1.75" of total slack when moved up and down below the swingarm. This is a rough measurement, as you now go to the other side and make the same approximate number of turns on the right side adjuster.

NOTE: When measuring chain slack, the idea is to measure the chain approximately mid way between the sprockets and measure the total distance when the chain is pushed toward the swingarm and pulled away from the swingarm. Use a link pin as a reference. When getting to your final adjustment, rotate the rear wheel and check the chain at it's loosest and tightest points, as the measured slack will change as the wheel is rotated.

Step 4

Recheck the chain slack and adjust both sides until the chain again has approximately 1.75" of total slack. Now with the "T" edge, measure the chain (left) side from the rear of the swingarm to the adjuster block and then do the same on the right side, adjusting it to match the reading from the left. Measure the chain slack again and adjust as needed until both sides are exactly the same and the chain has roughly 1.75" total slack measured midway below the swingarm.

Step 5

Take the bike off of the stand and have someone sit on the bike and measure the slack again at its tightest and loosest points. Adjust both sides as required, making certain that your final adjustment is identical on both sides when measured with the "T" edge and the chain has no more than 2.0" total slack and no less than 1.6" total slack. Tighten the chain adjuster lock nuts while holding the adjuster bolt with the other wrench. Make certain you don't "readjust" the bolts while tightening.
Place the bike back on the stand and torque the rear axle nut to the factory specified tightness.
 
:clap::clap::clap:

Is a "T" edge one of those nifty alignment tools that go through the axle and have the rods that point forward?
 
I just do it the way the manual says (sidestand) and if it's off I readjust and do it again until it's correct. Just replaced my chain and sprockets after 33000 miles and all were worn evenly.
 
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