Cam chain tensioner

[FFMan]

Just taking the head off to investigate the low compression and the book suggests i should be able to grab the tip of the tensioner with some pliers to insert the holding wire.

The tip on mine is way too far down to be grabbed - what does this indicate ? I got the cam out without a fight without lifting the tensioner anyway is it ok ?

See blurry pic

 

Edited November 13, 2017 by FFMan

[BOAB]

Cam and/or tensioner are way worn out.  The triangular part should protrude enough to grab it.

[Trailryder42]

That indicates the chain needs to be replaced. As the chain wears and stretches, that wedge is pulled down by spring tension and it acts on a guide that keeps the chain tensioned properly. When it is pulled down that far, it means the chain is stretched/worn beyond what the tensioner can compensate for any longer.

[FFMan]

i did wonder about this, and the fact i could get the cam out a little too easily.

do i just replace the chain, the tensioner itself didn't seem too badly worn when I recommissioned it, or does the lot come as a kit of parts ?

Any recommendations for sources or is this best oem ?

 

[Trailryder42]

6 hours ago, FFMan said:

i did wonder about this, and the fact i could get the cam out a little too easily.

do i just replace the chain, the tensioner itself didn't seem too badly worn when I recommissioned it, or does the lot come as a kit of parts ?

Any recommendations for sources or is this best oem ?

 

OEM is best. What year 250? Can be had alone. $79 from RMATV.

https://www.rockymountainatvmc.com/oem-parts/Honda

[BOAB]

Take a look at the tensioner while you are there, I've seen them crack.

BTW, I use a vice grips on the triangular part, makes it easier to grab and put a pin in.  Otherwise you sort of need 3 hands.

[Oil Baron]

I would replace only the chain first and see how that changes the wedge position.  

You can make a hook with a stiff wire to reach down inside and pull the spring/wedge up.

[gt63]

I'm thinking if you have a low compression issue your cam chain jumped and you have bent valve stems most likely on the intake side, you may have piston damage as well. 

[vicxr400]

definitely needs a new cam chain. with the chain tensioner being it needs a new chain id remove it completely to check the rubber follower for chunks missing from chain slap and as stated age cracks and shrinkage. there are 2 wedges in the top of the tensioner. the long flat spring loaded one connected to the chain follower and the hole for the setting pin at the back and a short spring loaded locking wedge at the front. the locking wedge at the front has to be pushed down to release the wedge at the back so it can come up to get the setting pin in the hole. fully held back ready to be installed with a new chain. the idea of the 2 wedges is a one way lock. only free to move one way once set to assure even consistent pressure on the chain. going by this and your other thread time to rebuild the top end and thoroughly check the bottom end. give that ol girl some lovin so she can love you back for years to come    good luck  let us know how you go.....cheers

[FFMan]

thanks for that. weirdly my tensioner has no hole for a holding wire to be inserted. I guess it isn't genuine or original but then the old girl has some racing history and at some point was well looked after. the plastic runners all look ok but the chain has visible play at each joint.

taking all the bits to the machine shop tomorrow to get an educated opinion on bore and cam train.

i split the case when recommisioning to fix the gear change, the bottom end is sound, those honda cogs looked brand new !

[creeky]

I would put in a new tensioner, I have seen two with broken springs on well used bikes rendering the tensioner ineffective.