SOHC.co.uk Forums > CB350/400
Why do we adjust camchain tension
marroinia:
Hi every one!
I finally replaced that camchain today.
The new chain is 63.7mm long when splitted, so was the one I removed...I feel like I spent time and money for nothing. It has been changed not long ago and that probably matches to head gasket change claimed by PO. Better be safe than sorry: the bike has a new camchain again... can't be bad -_-
Anyway, while playing around again with camchain tensionner, something poped up to my mind: I did a ride not long ago, after last time I opened the engine and post here, and deciced to "true" the tension to reduce camchain noise while engine hot, following normal procedure: noise became worst. Today, I noticed that the tension provided by the tensioner blade is stronger that the springs behind the pushrod.
When I screw the tensioner blade upper part [5] all the way down and untight the push rod bolt in front of engine [12]: the chain become loose.
I have to loosen the two screws [19] back around 6mm on the upper part [5] then lock the push rod bolt [12], then tighten the upper part to get proper tension on the chain.
I'm quiet lost here, the horse shoe isn't seized...did my tensioner blade become harder with age? Like it fossilized? Springs are too old with only 25000kms?
Anyone can help me?
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Bryanj:
It was never a good system from new.
There are several things that happen
1 the springs pushing the horseshoe go weak
2 where the clamping bolt tightens on the flat on the rod it makes a little indent and when you loosen the bolt the retighten the end goes back into the indent already there
3 the tensioner plunger gets a little tight in its bore.
My method for tensioning is loosen the clamp bolt, put som weight onto to kickstart so that the engine is just about to turn then whilst holding this tension tighten the clamp bolt.
You can also remove the blanking cap and push on the rod end then tighten bolt but as you need to do that with engine running hands get hot on exhaust
billywingnut:
I tend to agree with your last post Marronia, I fitted a new cam chain and guides when I had the engine down a couple of years back. I noticed the chain was noisier after adjusting when the engine was hot. I have the rocker cover off at the moment and checked the chain for play and was surprised by the amount of play. When undoing parts 19 the tensioner did lift part 5 slightly say 2 mm. I thought perhaps the rubber part 4 might be missing or damaged, but no, it is fine. So like you I intend loosen bolts 19 and increase the tension a little. To be honest it was n't very noisy but I like things to be as good as I can get it.
Orcade-Ian:
Now that’s a strange coincidence,
I’m nearing completion of the ‘Scottish’ 400/4 and needed to get pictures for the agreed value at policy renewal so I didn’t fit everything finally around the cam cover. Now I’ve finished zinc plating all of the cover bolts and other bits I decided to remove the cover for the new gasket, having read this post and thought I would investigate. I had already sorted the horseshoe when I had the thing completely apart and it was as free as a new one. I had NOS springs from years ago, new damper rubbers, new gen tensioner blade and new gen guide, together with a new genuine DS endless chain - everything Honda.
With the cam cover off, I loosened the adjuster and heard the whole thing move under spring tension. HOWEVER, just as Billy and Marroinia report there is still slack in the chain. I must admit, I’ve never checked the system this way before and not had problems. So what’s going on here?
Ian
Bryanj:
Ian, if you still have the cover off try adjusting again with the tension on the crank as i posted and see if the chain is tighter
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