Timing Chain Sprockets

[Bizcocho]

I've read a lot of posts about replacing timing chains. Is it usual to leave the old sprockets? Nobody mentions replacing them for the timing chain, but for the drive chain they are always mentioned and almost everyone seems to change them.

Also, people discuss slapping and rattling. The noise my engine makes seems quite similar to valve noise, but two people have said it sounds like a timing chain. Is there a good way to tell? Is the ultimate diagnosis taking off the valve cover and feeling the tension?

Thanks!

Rich
'80 GS550E

[earlfor]

I've read a lot of posts about replacing timing chains. Is it usual to leave the old sprockets? Nobody mentions replacing them for the timing chain, but for the drive chain they are always mentioned and almost everyone seems to change them.

Also, people discuss slapping and rattling. The noise my engine makes seems quite similar to valve noise, but two people have said it sounds like a timing chain. Is there a good way to tell? Is the ultimate diagnosis taking off the valve cover and feeling the tension?

Thanks!

Rich
'80 GS550E

The timimg chain runs being constantly dipped in an oil bath, so sprocket wear is nearly nonexistent. The timing chain tensioner is automatic and tension is not adjustable. If the tensioner was not working,cam chain slap would be a lot louder than any possible valve ticking. The tolerances in air cooled engines are large in comparision to the newer watercooled stuff. A noticable amount of mechanical noise is normal and necessary. Its when you cant hear your valves that you should be worried. Dont worry about the sounds, you'll get used to the "music".

Earl

[hampshirehog]

Final drive sprockets need replacing as they wear i.e. all the crap picked up on the chain effectively sands them down, very gradually. Your cam sprockets don't wear, as they run in an enclosed, well oiled environment. (Well, ok they will wear but only after a massive mileage).

The cam chain also follows the same pattern - however, it will after time stretch. Cam chains do need, in theory, to be checked for this, though they can last a long, long time. My manual states the service limit as 1/4 inch per foot stretch, which is pretty useless advice as you have to take the chain out to measure this. Far better to look at how much adjustment is left on the tensioner and judge from there.

I've never replaced a 550 cam chain by the way and I've had some massive mileage bikes which have been severely abused by POs. I suspect all that top end noise is good and healthy valve chatter. (If it goes completely quiet up there you need to do something).

[Bizcocho]

Thanks Earl,

Another great insight from GS resources. This forum is great.

Rich

[earlfor]

[quote=hampshirehog;846824

The cam chain also follows the same pattern - however, it will after time stretch. Cam chains do need, in theory, to be checked for this, though they can last a long, long time. My manual states the service limit as 1/4 inch per foot stretch, which is pretty useless advice as you have to take the chain out to measure this.

Far better to look at how much adjustment is left on the tensioner and judge from there
quote


There is no means of adjusting cam chain tension on a stock, automatic cam chain tensioner. It is not possible.

Earl

[hampshirehog]

Earl,
what I mean is if you pull off the automatic tensioner, you'll be able to judge how much adjustment is left (based on how far the plunger is out) = how stretched the chain is. More for piece of mind on a 550 though - bound to be plenty left (and said with a bit of tongue in cheek as the manual advice is so poor).

[earlfor]

[quote=hampshirehog;846847]Earl,
what I mean is if you pull off the automatic tensioner, you'll be able to judge how much adjustment is left (based on how far the plunger is out) = how stretched the chain is. More for piece of mind on a 550 though - bound to be plenty left (and said with a bit of tongue in cheek as the manual advice is so poor).[/quote


That would only be useful if you knew precisely how far out the plunger sat when engaged with a new cam chain and you locked the engaged plunger down on the worn chain, removed it, and were able to compare measurements.

heh heh
earl

[tkent02]

The chain is fine, it's a 550.
Find something else to fix.

[Nessism]

The factory service manual has a spec on cam chain wear: max length of 157.80mm (6.213") measured over 20 pins. 20 pins is roughly the length of the chain from the top of the intake cam to the exhaust cam so you can measure it with the chain in the engine by removing the valve cover. Salty Dan and I measured his 1000G cam chain with 70,000+ miles and it showed no wear at all.

[Nessism]

The chain is fine, it's a 550.
Find something else to fix.

You taking over for Grandpa now that he has moved on?:-?

[Suzuki_Don]

The factory service manual has a spec on cam chain wear: max length of 157.80mm (6.213") measured over 20 pins. 20 pins is roughly the length of the chain from the top of the intake cam to the exhaust cam so you can measure it with the chain in the engine by removing the valve cover. Salty Dan and I measured his 1000G cam chain with 70,000+ miles and it showed no wear at all.

So you saying I wasted my money replacing the camchain while the cases are apart on my 550/650. BTW if you are going to replace a camchain there is no-one around as cheap as Z1 for high performance camchains.
Cheers. Don

[psyguy]

don, mate, you havent been paying attention to the details in the service manual, eh?

just kidding

guilty of the same thing myself, too many bloody details around measurements and inspection of the internals...

So you saying I wasted my money replacing the camchain while the cases are apart on my 550/650. BTW if you are going to replace a camchain there is no-one around as cheap as Z1 for a high performance camchains.
Cheers. Don

[Suzuki_Don]

don, mate, you havent been paying attention to the details in the service manual, eh?

just kidding

guilty of the same thing myself, too many bloody details around measurements and inspection of the internals...

Just reckoned I'd replace it because the bottom end was open.
Cheers Cobber