Author Topic: Cam shaft tensioner and guide replacement  (Read 1391 times)

Offline SeanFD

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Cam shaft tensioner and guide replacement
« on: October 12, 2020, 06:24:49 PM »
I have been trying to replace the camshaft Today adn it has been a frustrating exercise; now I need some advice!

I struggled to get the chain onto the sprocket having fed the shaft through both and lined up the marks on the sprocket with the case. After several futile attempts, I resorted to reading the Haynes a bit more closely and discovered that the last pieces of the puzzle were the tensioner and guide. Mine were already in place so I took them out.

Happiness and joy, the chain went on a treat. Now to put back the bits. The tensioner went in fairly easily and will, I hope allow the retainer to tighten down fully The guide is anther thing altogether. I cannot get it to slide down fully.

It was fully seated before I removed it, but now it sits about 1cm high and no amount of pushing, tapping or manipulating the bottom end with a rod will make it go further.

Is there a trick to this? Any thoughts or suggestions appreciated.
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Offline Nurse Julie

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Re: Cam shaft tensioner and guide replacement
« Reply #1 on: October 12, 2020, 07:11:27 PM »
It will go in but it will need a very hefty push as long as its in the correct place with the foot of the guide going in the bucket thingy and the tentioner backed off. It may already be in the bucket thingy, can you get the guide to flex enough to do the top bolts done up?
« Last Edit: October 12, 2020, 07:14:00 PM by Nurse Julie »
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Offline SeanFD

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Re: Cam shaft tensioner and guide replacement
« Reply #2 on: October 12, 2020, 07:27:03 PM »
It’s the other one Julie, the one at the front without the top cap.

The cap is not yet bolted down. It sits up a little, but I think will seat properly when I tighten it up.
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Offline Nurse Julie

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Re: Cam shaft tensioner and guide replacement
« Reply #3 on: October 12, 2020, 07:36:42 PM »
It’s the other one Julie, the one at the front without the top cap.

The cap is not yet bolted down. It sits up a little, but I think will seat properly when I tighten it up.
Ah, yes, of course, silly me  ::) ::) ::)
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Offline SeanFD

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Re: Cam shaft tensioner and guide replacement
« Reply #4 on: October 12, 2020, 07:56:34 PM »
So no silly ideas?  :D
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Offline Nurse Julie

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Re: Cam shaft tensioner and guide replacement
« Reply #5 on: October 12, 2020, 08:04:19 PM »
So no silly ideas?  :D
No ideas at all, silly or otherwise other than persevering 😕😕😕
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Online TrickyMicky

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Re: Cam shaft tensioner and guide replacement
« Reply #6 on: October 13, 2020, 08:14:20 AM »
Y'know, it must be nearly 3 million years ago when I had the head and barrels off my 400, but I seem to remember that on re-assembly, you fitted the chain to the sprocket, observing the timing marks on it, then fed the camshaft through the centre hole and bolted it into its correct location. I certainly remember doing this on my 750 which if I remember had "ears" in it so that the camshaft would pass through the centre hole. Hope I haven't lost the plot completely and dreamt all this up!
     Regards, Mike, from the Twilight Home for the terminally bewildered.

Offline SeanFD

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Re: Cam shaft tensioner and guide replacement
« Reply #7 on: October 13, 2020, 09:09:19 AM »
Haynes says to feed the shaft through both chain and sprocket, line things up and then put the chain on and finally put the guide/tensioner in. I got all teh way to the very last step; now the guide slipper won’t slip.

Maybe your way would have been better as then I could have left in the guide and tensioner. Out to try again shortly.

They say it’s short-term memory goes first  ;) You are correct; the 750 sprocket does have “ears”
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Offline Bryanj

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Re: Cam shaft tensioner and guide replacement
« Reply #8 on: October 13, 2020, 09:49:05 AM »
Its a long time since i did a 400 but the 500 front guide goes inside the chain loop not ouside and if you fit it wrong the chain dont fit

Offline SeanFD

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Re: Cam shaft tensioner and guide replacement
« Reply #9 on: October 13, 2020, 04:36:22 PM »
On the 400 it goes outside Bryan... I hope!

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CB750 K2 - Ridden from Belfast(SA)-2-Belfast(NI)!
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CB400F Supersport - Rusty - not any more!

Offline Bryanj

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Re: Cam shaft tensioner and guide replacement
« Reply #10 on: October 13, 2020, 04:53:02 PM »
Like i said its been a long time, just trying to throw ideas.
On the G5 with same horseshoe idea we used to use a long screwdriver to push the horseshoe down with clamp bolt loose then nip up bolt whilst holding at fully down

Offline SeanFD

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Re: Cam shaft tensioner and guide replacement
« Reply #11 on: October 13, 2020, 05:10:46 PM »
If you check out this vide at about 4:00, you can see how it’s meant to go:

https://www.youtube.com/watch?v=YACuV9E3f7w

Mine looks like this after much gentle persuasion:

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When I set the cover on it’s like this:

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I’m just hoping that when I put in the rubber and tighten it down it’ll be OK. 😬 🤞
CB750 K2 - Ridden from Belfast(SA)-2-Belfast(NI)!
CB750 K1 - The less, said the better!
CB450 K1 - A work in progress.
CB400F Supersport - Rusty - not any more!

Offline Nurse Julie

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Re: Cam shaft tensioner and guide replacement
« Reply #12 on: October 13, 2020, 05:14:48 PM »
Sitting flush like how he shows in that vid is how mine sat.
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Offline Nurse Julie

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Re: Cam shaft tensioner and guide replacement
« Reply #13 on: October 13, 2020, 05:41:31 PM »
Here's a photo of mine, it's just sitting proud by a couple of mm actually in this pic but I know it sat flush with a gentle pressure

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Offline SeanFD

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Re: Cam shaft tensioner and guide replacement
« Reply #14 on: October 13, 2020, 10:33:43 PM »
Well I “tapped” it in and it is firmly seated. I can see the bottom end so it is in the right place, so the proof of the pudding ...

Now I just need to get the cover on, which brings me to my nest question: does anyone have a good diagram showing the length and position of all 27 bolts in the cylinder head cover; reading teh parts fiche is difficult, to say the least.
CB750 K2 - Ridden from Belfast(SA)-2-Belfast(NI)!
CB750 K1 - The less, said the better!
CB450 K1 - A work in progress.
CB400F Supersport - Rusty - not any more!

 

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