Thread: Cam Chain Tensioner pushrod Question (c pic)

Here's a Question for you engine experts. Why does my Cam Chain Tensioner push rod have uniquely placed machined holes? (In the parts catalog it doesnt show holes.) Obviously for oil, but exactly why. If they were for lubrication it seems they would be symmetrical in placement. It seems like some kind of hydrualic function ????

The reason I ask: I stupidly put the spring in first upon installing the rod. It took a hanger with a hook to get it out. The spring will need replacing but it may have scratched the sleeve where it sits. It may have but if it did it was barely.
The engine is lifan 107cc. Thanks for any opinions or similars!

Originally Posted by Adam-NLV

Here's a Question for you engine experts. Why does my Cam Chain Tensioner push rod have uniquely placed machined holes?

The tensioner bolt does not only have holes, it also has a check valve (a small spring-loaded steel ball) at its end. What it does is to pump up oil pressure by sucking oil through the holes you mentioned below the rod with cam chain movement until the chain doesn't move significantly anymore. The oil dampens the chain movement.

Thanks mfro, for your explanation. Wow, What an ingenious cam chain tension system! The more I learn about this little bike, the more I dig it.