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Timing Chain Deflection Test


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A friend told me that the timing chain can be checked for wear by doing a deflection test. This deflection test is supposed to give some indication of how much "play" there is in each link and the "play" will indicate how worn the links are. The way I see it the best way to accomplish this test is to collapse the chain into two rows and position it so that the bearing centerlines in each link are pointing up. Holding the chain at one end in this position will cause the other end to "droop". Like a cantilever beam. So here are my questions:

1) Has anyone done this before?

2) Does anyone have new chain that can be tested?

I know, I know - Just buy a new chain, right? The motor I am rebuilding was a factory rebuild and the chain looks pretty good. I would like to reuse it if possible.


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JUST BUY A NEW CHAIN ! because :

there are many ways to measure chain wear

one is to lay the chain straight with a ruler

along its side and pull the chain out straight.

measure the distance from each pin. A worn chain will

show longer gaps in the pin spacing as you go along the length.

or hang the chain with the side plates facing down

not how far - the drop of each end of the chain compared to a

new chain. The New chain will hang straighter - not drop

as much at the ends as the worn chain.

Most of the chain wear takes place at the pin, side plates where pins

meet, and the bushings the pins ride in. It is assumed that any

timing chain, 1-row or 2-row chain has served it's purpose and should be replaced at 100,000 miles.

Sooner or later depending on operating RPM's, condition of oil, over heating history, Nutt Behind The Wheel -

all factor . Camshaft timing retards with chain wear - power drops off.

If you want optimum power from your motor - replace the chain sprockets with the chain



'86 R65 650cc #6128390 22,000m
'64 R27 250cc #383851 18,000m
'11 FORD Transit #T058971 28,000m "Truckette"
'13 500 ABARTH #DT600282 6,666m "TAZIO"

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Guest Anonymous

Chains wear as do the sprockets turning them. Chains also last a long time. If you put a new chain on old sprockets, you introduce new wear patterns and risk the same, if not more, wear than if you left things as they are with the old chain.

If your chain is 30+ years old and seen a life at 8000 rpm chasing Ferrari's, I would be inclined to hang it on the wall, but as you say this is from a rebuilt engine, how recent, what kind of operation, what kind of maintenance are all considerations for keeping the chain and reusing it. I would compare it with a new chain for length and horizontal deflection. As most motorcycle mechanics will tell you there are any number of earmarks for chain wear that are acceptable. If worst comes to worse and your chain is so worn as to prevent decent valve timing, you can always swap the chain after the head is in place by using a master linked chain or by pulling the front timing case cover. My current M10 has used a masterlinked cam and oil pump chain for 36000m and I would expect them to last much longer.

My hunch is to reuse the old chain with the already used crank and cam gears. This is not scientific, and opinions may vary, especially since I have never even examined your chain. I could also advise you to exchange your tires with new ones, for many of the same reasons!

Good luck, but you probably don't need it.

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A chain is built with the same pitch as the sprocket tooth pitch. If the chain has worn it's pitch will increase.

So, just wrap the chain around the cam sprocket and hold it against the sprocket at two points 180 degrees apart with one hand and lift the chain link at half way (90degrees). Whatever it lifts indicates wear. A new on will not lift at all.

A worn chain will tend to ride up on the teeth because of it's increased pitch and run tight. Motor cycle guys know this. It will also wear the sprockets because of the wiping action as the teeth engage the chain and as the chain lifts off the tooth on the return.

Simple stuff!

A radiator shop is a good place to take a leak.


I have no idea what I'm doing but I know I'm really good at it.

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I forgot to mention in my earlier post that the worn chain test I described can be done with the engine assembled, such as when you adjust the valve lash.

A radiator shop is a good place to take a leak.


I have no idea what I'm doing but I know I'm really good at it.

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