Chain Measuring Procedure

[Jaybird]

Measureing your chain to see how far it has elongated past original pitch length is very important if you want to keep your chain and sprockets in optimum running order.

There are several methods given to measure a chain and see just what percentage of growth it is at, but I want to offer up this method for those of us who want to know precisely where our chains stand. Although a tape measure will do a much better job than the old "three finger on top of swingarm" , the "pull away from the back sprocket", or the "lay it on the floor andf flex it" methods, I want to offer the following method as the absoulte best way to corretly and accurately see where your chain is at:

Chain Elongation
Chain stretch is calculated as the total amount of elongation caused by wear on the pin and bushing, but not caused by deformation of the link plate. Remaining chain life can be estimated by measuring chain elongation.
This method can be used for any number of links, however the more links used the more accurate the calculation.

*(refer to the graphic provided)
1. The chain should be measured by stretching it slightly.

2. Measure the distance, using a vernier, of the inside (L1) and outside (L2) of rollers at both ends of the measured links, to get measurement (L).

L= L1+L2
        2· 

Chain elongation can then be calculated.

Chain Elongation= Measured Length - Std. Length x 100(%)
                                               Standard Length 

Standard Length = Chain Pitch x Number of Links

 

[WaltCMoto]

Measureing your chain to see how far it has elongated past original pitch length is very important if you want to keep your chain and sprockets in optimum running order.

This makes no sense to me. Lets say my chain is worn-stretched 50% of its useable range. How does this relate to keeping the chain and sprokets in optimum working order. The chain has to be tentioned and lubed properly to maxamize life, no matter where it is within its useable range.
If my owners manual says to measure over 20 links and the useable range is 12" to 12 1/4" , then when it mesures over 12 1/4, its out of spec. Besides, how many people have a 12" or larger veneir.

 

[Jaybird]

Walt,
You will notice I said that this will work with any number of links. Measure only six links if you have a small vernier. (you did pull up the picture, yes?)

It relates to keeping you chains and sprockets in working order because no matter how well you clean/lube/adjust, once your chain has elongated past 1.5% of it's original pitch length, it can and will start to damage the teeth of your sprocket. If you keep an eye on your chain, and know exactly when it reaches 1.5% of it's original length, then you can change it out without any damage having been occured to your sprockets. Hence...both chain and sprockets in optimum running order at all times.

Maintenance practice will dictate how long it takes a chain set to get to the recommended state.

This is by far a more accurate way of measuring your chain than any manual gives. Unless of course you have a tape measure graduated in .001's and an eagle eye.

 

[BRush]

Just so I understand:

“Standard” Length = Chain Pitch x Number of Links

Is there a way to decode the link pitch from the chain size number (i.e. “520”)?

Wouldn’t it be better to use as “standard” the (L1 + L2) / 2 measurement of a brand new chain before it’s seen use?

 

[Jaybird]

All chains that start with a designation of 4..ie. 420, 428, etc...have an exact pitch length of 1/2"
Those that start with 5, 520's etc....have 5/8" pitch.
Those that start with 6, have a 3/4" pitch.

So if you are measuring a 520 chain, to figure standard pitch length you take the number of links you decide to measure and multiply that number times .625 (5/8).
6 links x .625" = 3.75" (standard length for six 520 links)

 

[Danman]

This is the procedure I was given for a cam chain stretch. Execpt that it was 20 links and you measured between the pins on the side of the chain. Once it was past a certain lenght it was toast.

 

[Jaybird]

It would work the same as measuring the rollers, but it is tough getting the ID side of a vernier caliper between the pins to get a good measure. The pins dont stick out far enough.
Actually, using a tape and measuring center-to-center on the pins is sufficient to see where your elongation is. The method I show above is just a bit more accurate. (measuring from side to same side with a tape will get you within say .010~.015 thousandths of dead on...a small tic mark on a machinists rule is about .010 wide)
BTW...this method is from Tsubakimoto, makers of Tsubaki Motorcycle Chains. Largest roller chain mfg. in the world.

 

[JasonWho]

Hey, Jaybird. That is a good tip. Thanks. My Kawasaki KDX 200 service manual mentions the center-to-center pins method and hanging a 20 pound weight on the bottom run of links. Maybe a metal yardstick would work better than a tape measure, but I am sure a tape measure is better than what some of us (including me) have used, which is nothing! :-)

Thanks,
JasonWho

 

[Jaybird]

If you do use a rule or a tape to measure center-to-center, try going from the side of the pin on the first link to the same side of the pin on the last link.
This is much more accurate than trying to eyeball the center of the pin, and accomplishes the same task.