I believe the theory is correct, that the tensioner grabs a new tooth when the chain/engine is cold....then overtensions the chain when things warm up.  It doesn't take a new tooth every time the engine cools down - but evidently it gets a new tooth too often.

We are not the only bike that has tensioner issues - and a lot of the sport bikes have aftermarket manual tensioners that can replace the automatic tensioner.  I am tempted to just take the spring out of my tensioner - but leave the pawl in place to prevent the tensioner from collapsing (or putting a very weak spring in the tensioner).  This would in effect convert the stock tensioner into a manual one.

norm92de wrote on 05/09/16 at 12:10:17:

Bending the rear is a thought, but I don't think it will offer much relieve.
It is pretty stiff and the my main concern with bending it is popping off the plastic guide.

A manual adjustment taken up every service would be nice.

I have friend who races and they manually adjust their chain every race. On a Kawasaki I believe.

I left the spring out thinking that when the motor heats up the chain expands ,the tensioner moves out but when it cools it did not move back which stressed the chain. Some have rotated their motors when working on their bikes without the tensioner in place and not had the chain jump a single tooth on the timing gears. how much tension do we need? When I redid the plunger I ground three small flats on it to prevent any hydraulic lock up, the bike runs strong ,gurgles on decell ,never,backfires,and rarely poofs on shutoff (150 main jet may be a little rich but this protection . I haven't got the new anti kickback starter gear its a 95)

I think you guys are on to something, the whole locking ratchet isn't very good design once you study on it
Actually a simple change to a pawless, spring-loaded tensioner could be a good solution
note that automotive serpentine belt tensioners use simple spring tension

Art Webb wrote on 05/10/16 at 07:15:45:


The belts with spring tension are all driving things like water pumps, power steering pumps, air conditioners....things that don't kick back.  Every cam chain or cam belt tensioner I have ever seen is either manually adjusted and locked in place - or is self adjusting and has something to resist instantaneous movement.....either a pawl, one way rod/ball clutch, or anoil/piston device that tensions and also restricts fast movements if the chain is loaded in the wrong direction.

The problem that I see with no pawl....is the valve spring will attempt to push the cam forward at low rpm, and it could result in some weird vibrations of the cam chain.  When the valves are opening and closing the exhaust valve opens first and requires a strong force in the cam chain, then as the exhaust valve closes the valve spring will push on the rocker arm and cam lobe and push the cam chain forward causing slack in the cam chain, and then just before the exhaust valve closes the intake valve begins to open and it will require a strong force in the cam chain - then as the intake valve closes the valve spring will again try to push the cam chain forward and could result in some slack.  When the chain tensioner locks the movement of the chain...the different loading conditions will not cause the chain to jump around.

I believe that there must be a reason that "all" engines have a cam chain or cam belt tensioner that restricts the movement "backwards".  Some are sophisticated enough to allow excess tension to be released slowly as the engine warms up....the Porsche tensioners have springs that set the tension, and a hydraulic piston that restricts fast movements.  Originally these tensioners worked fine - but on occasion the hydraulic part would wear out and the chain would rattle....so later on an improved version was developed that was pressure fed through a small supply line and the tensioner got a fresh supply of engine oil.  Below is a photo of the early Porsche tensioners, and the spring is inside, and the tensioner is filled with oil, and there is piston that will allow the tensioner to move slowly in/out, and for installation you put the tensioner in a vice and compress the shaft slowly - then install it before the piston extends.

dave,can we get Porsche to design  our tensioners ,spring/hydraulic piston would be perfect !!!!!