Bits of metal found near inlet valve

[nairb]

Hello, I have owned the bike for over 11 years.  Its done at least 5k miles and has had several oil changes.  I decided to do a general service and check all the usual things.  Its been running ok, but it's winter time so never a better time.

I thought to check the valve clearance on all valves, so off with both the covers.  On the LH inlet side, there were some metal bits around the valve stem.
Pic of the lh inlet valve
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and a pic of the bits of metal.  A solid ring of sorts
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I am wondering if the cam chain tensioner has started to break up.  The cam chain is not as tight as I expected.
Is it possible to remove the lower cam tensioner (below the carbs) without taking the head off.

Has anybody else found bits like these.
Ta
Nairb

[Skoti]

It can seen from your photos that the tappet cover gasket has been scraped off with something very sharp which may have dislodged particles of alloy into the head.

If the particles are alloy and not metal as you state, then remove them and you're probably good to go, if not then it looks like a winter strip down and inspection is required...


Either way, good luck and Happy New Year.

Skoti

 

[nairb]

Well, I have pulled the cam chain tensioner out and expected to see some problem with it.....
For good or bad, it seems to be ok.
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It would be better to find out what's wrong without pulling the engine apart.  It's not been apart before, and I would prefer it to stay that way.

[nairb]

I thought I would post an update.... Other cb/cl450 owners might suffer the same issue.
To recap..... The engine was running OK, but the cam chain was making more noise than before.
So I decided it was time to service the thing.  When draining the oil, several lumps of metal dropped out.  Not good.  Then I found bits of metal around the inlet valves.

So it was obvious that the engine needed to be pulled apart to find the problem.

To take the cylinder head off these engines, the cam chain has to be split.  Oh, great.  Anyway, with that done, all was revealed.
The cam chain guide at the rear of the engine had disintegrated and had let the cam chain run slack.
Here is a pic of the item along with what it should look like.
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The part is no longer available.

So if your Double overhead cam 450 starts to sound a bit noisy ........ it might be best to have a look behind the valve covers. 

[Bryanj]

I am sure there was a firm making tensioners but not cheap, Ash would know

[taysidedragon]

Nasty! I hope you're able to find a replacement.

[K2-K6]

DK may have one here

https://www.ebay.co.uk/itm/335468025755

[K2-K6]

Or this one

https://www.ebay.co.uk/itm/361842087148

[Bryanj]

The second one is the name i couldnt remember, aparently used to have decent power reliable racers

[nairb]

Nasty! I hope you're able to find a replacement.

This is the reason I dont rev the life out of these old engines.  These 50 year old engines have old cam chain tensioners/guides.  I just potter about.  I was lucky.  It dident snap the cam chain or jump a tooth on one of the cam shafts.

[nairb]

DK may have one here

https://www.ebay.co.uk/itm/335468025755

Thanks......... I dident see this one and have purchased it.  The ones from USA will have a huge lump of import duty and extra postage applied.  But it is NEW, which is the preferred option.

You know there is a problem when DSS dont have one.

[Bryanj]

Whilst its out new cam chain and new rivet link of course

[nairb]

Whilst its out new cam chain and new rivet link of course

Oh yes.  But I was surprised to see that the DSS cam chain for this model is a continuous chain and needs to be split first to fit it.  And also buy the new rivet chain link as well.

[Bryanj]

How about this one on fleabay, dont ask for a link, my brain cant fathom those

[AshimotoK0]

I am sure there was a firm making tensioners but not cheap, Ash would know

I fixed mine with a kit from Cappelini in Italy.. they supply new pin and sprocket and the sprocket pushed off the roller and you simply press on the new one ... no heat required. Bernard Saunders used to be their UK supply guy, although I got mine directly from Cappelli as I traded some race valves off a CYB350 with him. I may also have a full assembly that's not too bad.