Honda-SOHC
SOHC.co.uk Forums => The Black Bomber Board => Topic started by: nairb on December 31, 2023, 12:25:58 PM
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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
[attach=1]
and a pic of the bits of metal. A solid ring of sorts
[attach=2]
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
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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
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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.
[attach=1]
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.
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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.
[attach=1]
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.
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I am sure there was a firm making tensioners but not cheap, Ash would know
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Nasty! I hope you're able to find a replacement.
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DK may have one here
https://www.ebay.co.uk/itm/335468025755
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Or this one
https://www.ebay.co.uk/itm/361842087148
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The second one is the name i couldnt remember, aparently used to have decent power reliable racers
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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.
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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.
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Whilst its out new cam chain and new rivet link of course
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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.
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How about this one on fleabay, dont ask for a link, my brain cant fathom those
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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.
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I fixed mine with a kit from Cappelini in Italy
I think you mean this:-
[attach=1]
The problem is that the original has worn the central part of the sprocket flat in one place. And it no longer turns
see pic..
[attach=2]
I have a used one on the way, but a new one is preferred. I think this is going to be a pain in the rear to put back together and get the cam chain threaded thru all those parts.
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I am not familiar with these models at all, but is this what you need? It's from CMSNL in Holland, and I'm assuming it is original kit. Mike.
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I am not familiar with these models at all, but is this what you need? It's from CMSNL in Holland, and I'm assuming it is original kit. Mike.
There are several new ones about. Either in Europe or the USA. Having bought stuff from both these places in the past, I know just how much extra tax gets applied to the price. Its been vat, import duties and the extra postage from the port of entry to the front door. It could add an extra £60+ quid.
I was surprised DSS did not have one. If I wait a few weeks, there might be a new one popup on eebay for less than £200.
Still..... at least the engine dident go bang with a snapped cam chain. I might have had something to moan about then.
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If you look closely at that cmsnl page you cant order it, only put it on a wishlist
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If you look closely at that cmsnl page you cant order it, only put it on a wishlist
OOPS!!! When all else fails, read the instructions.
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I sold my lovely bomber project earlier this year with all of the cam chain stuff NOS.
However, earlier on I got these before I found a NOS one ...needs reassembling but sprocket is really nice.
£20 plus £3.50 post if interested ..less than I paid when I bought. Needs a good clean though.
[attachimg=1][attachimg=2]
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You are going to have no bikes left at this rate Ash😳
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You are going to have no bikes left at this rate Ash😳
You'd be surprised ... still got loads .. but Bomber and CB72 were never going to happen realistically.
Member here has the bomber anyway so still in the 'family'
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The tooth form on that one looks immaculate Ash.
It doesn't appear to have any wear visible at all, a very good example that would essentially offer a virtual NOS part when cleaned.
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The tooth form on that one looks immaculate Ash.
It doesn't appear to have any wear visible at all, a very good example that would essentially offer a virtual NOS part when cleaned.
It may well be a NOS sprocket Nigel...I did swap a few for Capellini's ones....then I got a NOS one ...all back in the dark days of lockdown.
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£20 plus £3.50 post if interested ..less than I paid when I bought. Needs a good clean though.
Yup, pm sent
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If you look closely at that cmsnl page you cant order it, only put it on a wishlist
I dident look to close either...... the £192 quid made me move on quickly. I was expecting something for £50 from dss.
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Dont be daft DSS knows what they are worth
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Just thought I should post a pic of the offending bike. I dident think I would need to pull the engine apart. So there we go. Its not a K0.
[attach=1]
I did actually get the top exhaust from dss. And the bottom one from Germany (I think).
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But it is the more sought after CL, or so i am told
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Just thought I should post a pic of the offending bike. I dident think I would need to pull the engine apart. So there we go. Its not a K0.
(Attachment Link)
I did actually get the top exhaust from dss. And the bottom one from Germany (I think).
Honda never really changed/improved much in the cam chain tensioning arrangement.... Even for the 500T. The main problem is that one end of the exhaust camshaft can get poor oil supply at start-up and the associated cam lobe is often pitted. The key is to warm up the engine up fully at start up ...but yours is a USA bike so possibly never happened. If you think that idler is hard to source ...try getting the one with one sprocket and two rubber rollers... now that isa hen's teeth item with rollers that are not badly worn or rock hard. I took me 8 years to find a NOS one for reasonable money.
Cappellini do sell a cam cover modified to improve oil feed to the exhaust cam I believe.
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I remember you chasing a source of that camshaft Ash.
It was of course part of the "Dutch" thread in topic too.
That really made me think, and alter my fundamental approach in looking at failure of this type across different engines.
There's currently something of an epidemic in car engines that moved to "reliable" cam chains as opposed to toothed belt that gives a lot of failures to examine.
This honda problem just looks like oil supply, particularly the initial phase of running after just starting. I do think synthetic oils can offer a better outcome as well ....the Dutch thread more or less proving that, in my view. Hadid go the wrong way on viscosity though as he ultimately chased oil pressure as absolute and not the "replenishment" rate at bearing sites.
Low incidence of oil replacement is fundamental ... that now being seen with long gap in modern cars from silly service intervals. They also struggle with guide failure, often plastic in entirety, and fracture being common. But immediate supply of oil to components is of very high value, low viscosity usually helping that rather than "stalling " oil flow durometer pump by the pressure relief valve opening when cold ... effectively causing nil supply to reach extremities through that initial period.
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So, is there a particular reason these things fail. Is it a poor design or an oil way that gets blocked.
[attach=1]
This engine has had regular mineral oil changes and not revved too hard. Its done only? 12.5k miles.
I am surprised it failed. I am not looking forward to getting the cam-chain back on with all the timings correct.
Nairb
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Do you have more detail in photos of tge failed parts ? I looked at your original image early in thread, but couldn't see everything of interest in detail.
Did the centre bearing stay intact, and what does the spigot surface (that the r9llers run) on look like ? Is the bearing free and not gummed with sticky oil ?
Its a pretty harsh life in cam chains and their support guides etc, but that may shed some more light on it from detailed images.
Are you changing the chain, has it got obvious signs of length extending through wear ?
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Do you have more detail in photos of tge failed parts ? I looked at your original image early in thread, but couldn't see everything of interest in detail.
Did the centre bearing stay intact, and what does the spigot surface (that the r9llers run) on look like ? Is the bearing free and not gummed with sticky oil ?
Its a pretty harsh life in cam chains and their support guides etc, but that may shed some more light on it from detailed images.
Are you changing the chain, has it got obvious signs of length extending through wear ?
My experience (I had several used examples of that idler assembly) is that the needle roller bearing (same bearing as used on CB750/CB250/350K cam chain tensioners) fairs pretty well ... its the teeth on the sprocket that seem to get knadgered quite badly. Also the cogged rubber roller on the cam chain tensioner gets pretty hard and chewed up too.
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Interesting Ash, about the teeth. They usually wear generally if given a chain pitch out of ideal tolerance. Suggesting that the culprit us primarily of cam chain lubrication.
It would be interesting to see the original chain on this one, wrapped around one of the sprockets, then the opposite side from the two ends pulled up to assess for wear.
The design of these looks to be marginal in that later designs (750 as example) move to more curved guide rails, ultimately this mitigates chain "twang" which can be significant contribution in cam drive arrangements. Reducing noise too.
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Do you have more detail in photos of the failed parts ?
Here are 3 more pics. Nothing rotates or turns. It all seems seized up.
[attach=1]
no 2
[attach=2]
and finally
[attach=3]
Still not replaced the wheel yet.... Do I drill or unscrew the centre part.
It gives the impression of lubrication failure. But all the other wheels seem fine.
I have cleaned out the centrifugal oil filter. It was not too bad. Maybe I will simply re-build the top end. I think it was factory finished and not been apart.
I did mean to add that a brand new did chain will be fitted. I have not checked the old one. At 12.k miles on the engine, I think it should still be service-able..... But I should check
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[attachimg=1]