Cam chain knock?

[YoungEngineer]

I recently went up a weight in oil. I'm using 20w60 which has made a huge difference to consumption. I'm down to around 150ml per 1000miles. The engine pulls and sounds better then ever. However I have noticed very occasionally a knock when cold almost like how a loose chain would sound.


When the knock happens the rpm drops suddenly like there has been two components contact in the engine.


My question is, could a change in oil weight cause less tension on the cam chain tensioner?


The bike now has 98,000 miles, would it be expected at this mileage to replace the chain?

[The Mighty Gryphon]

The cam chain tensioner works off of engine oil pressure.  By going to a heaver weight oil, you may be preventing it from tensioning the chain adequately before it has reached final viscosity at operating temperature. 

I could see where slack in the chain could cause some minore variation in valve timing.  Probably not enough to cause major mechanical damage, but possible enough to affect the power delivery.  I would guesss that the amount of slack will be related to the amount of change in timing.

[YoungEngineer]

Thank you gryphon. I will keep that in mind. It could be a coincidence that I noticed this after the oil change. Might be unrelated. I will keep investigating.

[YoungEngineer]

I did not change the filter this time as it was done less then 1000miles ago. I'm pretty sure i would have noticed a missing oring.


This issue really is not a cam chain rattle. There is no rattle at all apart from.om the first second on a coldstart but there is sometimes. As in maybe once every 50 miles when at idle a sudden knock. Thinking about it, it really could be anything

[Areshuan]

Hello .   I am having the same issue 7 years later.
What happen to you problem? 

[The Mighty Gryphon]

I just ignored the noise.  It never hurt anything on my bike.  Your mileage may vary.