S40 Timing Chain

[roydm]

Hi,
Does anyone know how many miles I can rack up on a Suzuki S40 before changing the timing chain?
Are there other parts e.g. tensioner that I should change at the same time?
I have the workshop manual but it doesn't indicate above.
Thanks
Roy

 

[BrianPetersen]

Normally, there is no specified interval on changing timing chains. They are supposed to be a "lifetime" part.

Concern yourself with it when there is evidence of a problem: rattly noise, tension not being applied, etc. At that time, a proper inspection and diagnosis will reveal what needs to be replaced.

It is possible that the service manual gives a tolerance for the 20-link (or similar) length of the chain, in which case, inspection is possible.

It is also possible that by the time the chain or tensioner ever gives trouble, the cost of properly diagnosing and repairing it may be worth more than what the vehicle is worth at the time.

 

[roydm]

Thanks Brian,
Yesterday I found the tolerance measurement you suggested. It showed the chain on the bench but I think I can measure it in-situ just scaling up from the 21 links.
Regards
Roy

 

[EzGoingKev]

Are you asking because it is making noise?

 

[roydm]

No, the milage is approaching 50,000 km, I just thought it might be time.
My Klymer manual shows how to measure the stretch but doesn't indicate when would be a good time.
Regards

Roy

 

[EzGoingKev]

From what I have seen, chain tensioner issues are more common than chain issues.

A bike with a bad tensioner can cause a chain issue if run long enough.

A bad cam chain tensioner will cause the cam chain to make noise.

The GSX-R engines have had cam chain issues for a long time.

The 96-99 models would have the individual plates fail. The pieces would then tear apart the rubber dampers. This would result in one of two methods of engine failure. Either the chain would fail and take the engine out OR the rubber pieces would get sucked up into the oil pump pick up and starve the engine for oil. It was common procedure to remove the chain damper at the top of the cam caps to inspect it for abnormal wear.

In 2000 Suzuki then went to an oil pressurized cam chain tensioner. This made things more reliable, but it still had issues. This tensioner had a spring loaded pawl that engaged teeth on the telescoping shaft that would prevent the tensioner from backing off. The teeth would strip out. Hollow roll pins were used and they would shear under the pressure. The fix for that was to use the 1000cc model's tensioner on all engines as that one used solid pins. Also, the upper chain damper's mounting ears would snap off and jam the chain up. This occurred on racing engines and it is my belief that it was caused by the poor tolerances used by a US manufacturer of adjustable cam sprocket/hub assemblies.

The newest generation seem to be well sorted but I always throw a fresh chain in when rebuilding.