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What are the best indicators for early warning of the timing chain going out? ( non-intrusive of course )

45,000 mi on my R100, but what is the average life span of the chain and sprocket

1970 to 80 double roller chains usually last less than 50,000 miles. They hardly ever break, but get very noisy as the chain starts hitting the case. At that point the sprockets, espesialy the crank need to be replaced.

If the chain is done early, say 30 to 35,000 miles, only the chain can be changed with one with a circlip. The job is easy and only takes an afternoon.

Single chains from 81 last a bit longer and wear the sprockets less. They are even easier to change.

Another symptom is double images of the timing marks when using a strobe timing light.

Mine's an '82

No knocking of chain to case yet, no jumping of the timing mark under strobe.
Any other indicators?

Is the expected life any different for the post 81 models?

Garnet wrote:1970 to 80 double roller chains usually last less than 50,000 miles. They hardly ever break, but get very noisy as the chain starts hitting the case. At that point the sprockets, espesialy the crank need to be replaced.

If the chain is done early, say 30 to 35,000 miles, only the chain can be changed with one with a circlip. The job is easy and only takes an afternoon.

Single chains from 81 last a bit longer and wear the sprockets less. They are even easier to change.

The single chains started in 79. The same year as the points-in-a-can.

wirewrkr wrote:
The single chains started in 79. The same year as the points-in-a-can.

That makes sense, maybe it was Mercedes Benz that went single chain in 81.

Anyway Ray, BMW had much better luck with single row chains than MB or Toyota and they last longer than the doubles, probably about 10,000 miles longer.

At 45,000 miles I'd put it on this winter's to do list. The chain is pobably in modest shape and has not worn the sprockets. Simply grind off one link and put on a new chain with a removable link. If you wiat for the chain to flop around enough to show double images or hit the case you wull need to change one or both sprockets which adds a lot of work and expence.

Garnet wrote:

wirewrkr wrote:
The single chains started in 79. The same year as the points-in-a-can.

That makes sense, maybe it was Mercedes Benz that went single chain in 81.

Anyway Ray, BMW had much better luck with single row chains than MB or Toyota and they last longer than the doubles, probably about 10,000 miles longer.

At 45,000 miles I'd put it on this winter's to do list. The chain is pobably in modest shape and has not worn the sprockets. Simply grind off one link and put on a new chain with a removable link. If you wiat for the chain to flop around enough to show double images or hit the case you wull need to change one or both sprockets which adds a lot of work and expence.

The single row chains supposedly outlast the doubles. My theory about this, is that it is not because of the different chain, but that the chain nolonger has to drive the tach gear. The single row crank sprocket does seem to be made of a different temper steel than the double although I'm not sure if that's true with new crank sprockets. On a side note, all cams and cranks will accept either type of sprocket.

I have heard you can run a single chain on the outer of the the dual sprockets. Can somebody confirm that? My built-from-scratch 600cc /5 engine (currently consisting of the housing, the crankshaft and the camshaft) needs a chain when I get to it again in Fall.

Stephen

StephenB wrote:I have heard you can run a single chain on the outer of the the dual sprockets. Can somebody confirm that? My built-from-scratch 600cc /5 engine (currently consisting of the housing, the crankshaft and the camshaft) needs a chain when I get to it again in Fall.

Stephen

I've heard this too. As long as both sprockets are double row. Why couldn't you run single chain on the inner row only?
If that was possible you could get twice the miles out of those expensive sprockets. Run a single chain on one row until it's warn down....then put a chain on the other row the next time.

Having heard the same urban legend, I would imagine it is run on the outer sprocket simply for ease of access. Can't see why the inner sprocket wouldn't be as good.