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Discussion Starter · #1 ·
Hello everyone,

Im in the process of getting my recently acquired '73 CB450 up and going and pulled the front exhaust side cam cover to adjust the valves. There are two rubber seals that are loose on the cam. Can someone give me the skinny on these and if I need them? Do they just have to do with cutting down on top end noise and I can cut them out? Or am I royally screwed? Also found a loose piece of a seal when I pulled the cam tensioner, is this the one that disintegrates and isn't really needed? I hope so. Thanks gents!


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Normally you see those in pieces after all these years. Can't say I've ever seen one intact but not in the groove next to the sprocket, as both of yours are on the exhaust cam. They are for cam chain noise damping and are not mechanically necessary for safe, regular operation
 

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Discussion Starter · #3 ·
Normally you see those in pieces after all these years. Can't say I've ever seen one intact but not in the groove next to the sprocket, as both of yours are on the exhaust cam. They are for cam chain noise damping and are not mechanically necessary for safe, regular operation
That's good to hear. I will end up cutting them out then. Glad there's not a top end rebuild *immediately* in my future! I figured they were for noise dampening and I'm very surprised they just danced around in there all these years untouched.

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I find it amazing these cam chain damper rings have managed to free themselves from under the chain intact.I'd inspect closely that there are no old rings still under the chain and that these have not just been incorrectly fitted by a previous owner.Its fine to just remove them but they usually go brittle and crack under the chain, thats when they disintegrate ,drop to the bottom of crankcase and then there's a risk of them being sucked through the oil filter screen ,blocking oil ways and causing untold engine damage.The small bits you found in other pic on the cam chain tensioner side may well be from disintegrated rings on the inlet side.I'd remove the intake cam cover and do a good inspection on that side also rotating the engine at the same time to do a thorough inspection.These rings are more trouble than they are worth and the engine will run fine without them but for my money I alway strip and do a thorough clean on these engines.Some take the other view & say if it ain't broke then why fix it but having now rebuilt seven bombers I know what that can cost and there's only one way for me.Fingers crossed whichever way you go but I'd certainly do an oil change at the least ,filter what comes out & see if there are any signs there of other bits. Regards Chris.
 

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Discussion Starter · #5 ·
Thanks for the guidance. I've got the bike running pretty decent now but it did sit for a little bit before I acquired it and has a few issues I've mostly got remedied. Right now I'm going through the "adjust every single thing" phase because it needs it. Filter has been cleaned and it's about to be on it's third oil change in a week, and the motor seems to be pretty clean on the inside. Especially after somebody, (ahem, me) left the petcock on and I inadvertently ended up flushing the motor out pretty well, if you know what I mean!

Question on the valve adjustment, the tick marks are pointing away from the plugs as they should. But for the life of me I can't get a .006 gauge all the way under the cam lobe, let alone a .020. am I supposed to be able to slip my feeler gauge ALL the way in between the cam lobe and follower or does it "stop"?


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Cut them and throw them away. They will fall apart and clog up your oil passages sooner or later.
They are there to damper the cam and supposedly make things quieter. Not required.
 

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Question on the valve adjustment, the tick marks are pointing away from the plugs as they should. But for the life of me I can't get a .006 gauge all the way under the cam lobe, let alone a .020. am I supposed to be able to slip my feeler gauge ALL the way in between the cam lobe and follower or does it "stop"?

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Proper gap is .03mm, or .0012", which is a very thin gauge. The smallest in my set is .02mm. Note that the contact point on the cam follower is about 1/2 way to the valve stem, so the actual gap at the valve is about .06mm. I just did mine, and there is a spot where the feeler slips in, and moving the adjuster from that spot can make it stick again. Very tricky, and it really helps to have a third hand to tighten the lock nuts while the adjuster is held in place.
 

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Gap at the tappet/cam (by the book) is 0.0012".
Because the tappet pivot is asymmetrical, this translates to 0.002" at the tip of the valve - that's a more familiar number to us.
Most of us use 0.002" at the tappet/cam.
 

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I'm not sure about the later K series or if Honda by this time had changed the design but it may be worth mentioning here for others that there was a modification done by Honda on the early bombers to the oil pump inlet area to ensure that oil was sucked into the pump across the whole surface area of the oil filter screen.I've had two bombers where there has been a complete hole on the filter screen directly under where the pump non return ball sits.This obviously allowed larger particles/bits to be drawn by the pump leading to more possibility of blocking oil passageways and starving the cams of oil.This is when repairs get expensive so screens are always worthy of a good inspection and the necessary modifications are easy to do .I'll see if I can find the bulletin and post it up here. Regards Chris.
 

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Discussion Starter · #11 ·
Thank you guys for the info, in my research I haven't seen the bulletin so that's good to read. Last night after posting I pulled the intake side cam cover as well and would you believe it, half of each of the rubber rings were still on the cam as you guys predicted. I got those out and I'll be pulling the right side cover tonight to inspect the pickup screen. It seems like most of the rubber dampeners got caught in the cam tensioner assembly spring so that's good, but just to be sure (and before I waste another 3 quarts of fresh oil), I'm going to clean the pickup screen and do a thorough inspection. Thankfully the followers and cams look good as the top end was getting good oil flow. As per usual, this is turning into another bad case of "shipwright's disease"

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Discussion Starter · #13 ·
So another snag I've run into. On the right side of the motor I can easily adjust the intake and exhaust valves on the "T" marking on the rotor. I can get them dialed in easily and the feeler gauge can easily slide ALL the way underneath.

But on the left side, rotor on "LT" mark, I can't slide the feeler gauge in more than maybe an 1/8". I've tried turning the cam adjustment screws every which way and it doesn't matter, I can not get them loose enough to slide the feeler gauge ALL the way under. I'm not a dumbass, I promise, I just can't figure out why one side is easy to adjust and the right side won't cooperate. The followers look great, no flat spots or excessive wear as far as I can tell. The rotor is a replacement from another bike, but I didn't figure the markings would differ.

Also, I figured the adjustment would be made with the lobes of the cam pointing directly down at the followers, but they seem to both be in different positions between the intake and exhaust cams, is that correct?


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The rest of those rubber rings will be in the sump under the sump plate and thats fine whilst they stay there.Just changing the oil will not remove ALL of them and its a risk you take by not doing a thorough strip down & inspection. I wouldn't like to guess the odds for possible future oilway/cam problems. I know its a difficult decision for you to take so my recommendation would be for you to thoroughly study the Sticky that was made on this site on- 450/500 Valve adjustment on 31/12/2011 at 2.19pm.its already viewed here over 45,000 times. If you are satisfied you have done everything correctly i.e adjustment on compression stroke etc. and you still cannot get a feeler gauge in then my recommendation would be to do a full strip down so you can do a proper inspection of the cam followers etc .Regards Chris.
 

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^^^yes, my suggestion would be to double-check that you're on compression stroke for the left side. Turn the engine while watching the left intake valve and after it opens, and then closes, the next LT is compression stroke - then try to adjust the left sides valves
 

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Discussion Starter · #16 ·
^^^yes, my suggestion would be to double-check that you're on compression stroke for the left side. Turn the engine while watching the left intake valve and after it opens, and then closes, the next LT is compression stroke - then try to adjust the left sides valves
That was it, it finally makes sense to me. After reading that I went out and realized I haven't been putting it on the compression stroke. But once I did that you can bet I was able to slide the gauge freely through. I appreciate it, in all the 5000 sources I've read on the valve adjustment the importance of being on the compression stroke wasn't stressed enough and knowing when you were *actually* on the compression stroke.

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There's always more to learn with these old hondatwins and the knowledge and helpfulness of the guys/gals on this site is still in my view is second to none.Glad your'e on the way to getting it sorted.:) Regards Chris.
P.S. The 'Stickys' and search box on this site are well worth using - there is lots of information there gathered over the years and with a bit of a search you can find answers to many common problems .
 

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Those o rings are not needed and will only break down after some time and clog your oil passages. Get rid of them.
 

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Now found the bulletin re this:- Hope its readable Regards Chris
Hi Chris .. That Service Bulletin I knew existed but I couldn't find it anywhere, as Photobucket had deleted it on another members post.

I found it a bit hard to read so I typed out the text. We recently had a discussion I started on sohc.co.uk about the 450 oil pump, as we started a 'Black Bomber Board' on there, as a few of us recently started restoring CB450K0/K1's. I posted the SB on there and mentioned that you kindly provided the original, I hope you don't mind.

Later Alloy Body Oil Pump in K0 Bomber

OIL PUMP INSPECTION/MODIFICATION

APPLICATION: Engine No. CB450E-000001 to CB450E-1021156

We have found that some top-end and oil pump failures in CB-450units has been caused by
Foreign matter entering the oil system through damaged oil pump filter screens.

The oil pump intake port is surrounded by four screen-supporting oil guide ribs. These ribs must be separated as in Fig.1. If the ribs are jointed or partially joined, as in Fig.2, the oil flow to the oil intake port becomes highly localized. The localized flow will eventually work-harden, embrittle and break the brass filter screen. Any break in the filter screen allows foreign matter, trapped in the oil, to enter the pump, possibly fouling the check valve and damaging the oil pump.

We recommend the following inspection and subsequent modification if, during routine maintenance, any of the following conditions exist :

1. Cam chain dampers missing or broken.
2. Lubrication or camshaft failure.
3. The right hand crankshaft cover is removed to perform other maintenance.

oil pump mod 450.JPG
 
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