Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: RBoss on January 15, 2022, 03:04:29 PM
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Hi all,
I'm putting together the top end of my engine rebuild and I am not sure if the way I am putting back my cam shaft on the chain is correct.
I am trying to make the top dead centre of cilinder 1&4 correspond with the cam shaft but I am having trouble lining up the holes of the cam sprocket then. This is the best I am making of it now. What would you say?
Also the cam chain is very tight and it is difficult to fit it on the sprocket, i have to turn the tensioner "loose" in order to be able to fit the chain on the sprocket. Is that normal? (It is a new chain)
I have two situations:
1) either the cutout in the camshaft is not entirely horizontal to the top face of the head while the T-mark is correct
[attach=1]
[attach=2]
2) the cutout is horizontal but the T-mark is not correct
[attach=3]
[attach=4]
Am I doing something wrong?
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Got it! Is was one tooth off... :-X
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Correct it was 1 tooth out and yes they are a swine to fit when chain is new. You do know that you do not use a screwdriver in the adjuster slot dont you
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Correct it was 1 tooth out and yes they are a swine to fit when chain is new. You do know that you do not use a screwdriver in the adjuster slot dont you
I didn't know that, I suppose one should adjust the tensioner just by loosening the bolt and retightening it again and let the spring to its work? I guess I won't be adjusting mine soon as it is a new one?
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If you have a new tensioner blade the sideplates of chain wear two grooves into the rubber till rollers touch so adjust at 500 miles after rebuild same as oil change then every 1500.
DO NOT turn engine with a spanner on the big nut at points, lossen adj nut, put weight on kickstsart until crank is about to turn then whilst holding cranck tighten nut
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Hi everyone.. Hopefully you can help I’m coming to the end of an engine rebuild on my CB500K0. I’m having problems with setting the cam chain tensioner, the engine now has a new cam chain and new tensioner blade.The tensioner spring adjustment mechanism looks good and works fine on the bench, the tensioner spring adjustment works fine when fitted in the engine. The issue occurs when the cam chain is fitted to the sprocket on the camshaft, the engine is set at CYL 1 compression 15 degrees past TDC but the tensioner spring adjustment screw will not turn either way (obviously locking nut loose). It appears that the tensioner remains in the fully backed off state set for fitting the chain to the sprocket, it’s almost as if the new chain is too tight which is holding the tensioner in the fully backed off state. Am I reading this thread correctly that a new chain and tensioner blade will do this and needs some running until adjustment is required?
Many thanks
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New chain and new tensioner can mean little movement, can not repeat too often DO NOT turn that slot in the screw with any tool
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New chain and new tensioner can mean little movement, can not repeat too often DO NOT turn that slot in the screw with any tool
Thanks for the reply.. as per the manual I was expecting the tensioner spring to self adjust automatically from the fully backed off state held for installation. I was concerned when the tensioner spring didn’t self adjust at all when the locking nut was undone. I have only lightly manipulated the adjust screw to have an idea of what the problem could be, but the tensioner remains in the fully backed off state. Unfortunately the service manual doesn’t mention anything about this scenario with new components fitted. If this is normal for new cam chain and tensioner blade is it just a case of backing off the lock nut although the tensioner doesn’t move just retighten the lock nut and run the engine for ‘X’ amount of miles
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If it has been turned or forced, there could be missing teeth, or bent teeth. It is totally automatic. Here is a picture so, if you take the plate off you should see if there is any damage and if it is sliding ok.
[attachimg=1]
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The tensioner mechanism looks good and turns freely and spring adjusts on the bench the same as when it is installed in the engine. The problem only occurs once the chain is fitted to the cam sprocket and camshaft, My worry is if the new cam chain is too short making it too tight
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Maybe you don't need it, but others may have a look at this video shot by René van Maanen of Honda4.nl. It gives an idea how the tensioner works and why it is, you will not see the bolt turn, when you loosen the locknut to let it adjust; it will move just a fraction.
Mind you, the vid does NOT show how to do the adjustment, it only demonstrates what goes on. To adjust, either do it by the book or like Bryan has posted before. I do NOT recommend adjusting with a running engine like Honda's Owner's Manual CB500K3-CB550K3 suggests.
https://www.youtube.com/watch?v=8qJc6e5pa8M
Courtesy Renë van Maanen - Honda4.nl
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The tensioner mechanism looks good and turns freely and spring adjusts on the bench the same as when it is installed in the engine. The problem only occurs once the chain is fitted to the cam sprocket and camshaft, My worry is if the new cam chain is too short making it too tight
A new chain is tight, if it was one link too short you would never get it on. Come to think of it, i had a new cam chain out of the box once which was a 88 link box but, i did get it on but it turned out to be a 86 link.
Is your front cam blade in the correct way. The can should be between the blade and the inside of the barrels .
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Tensioner blade, guide and chain all fitted and routed as per the manual. Just spoken to Honda- classics (always helpful) they advised that with new components fitted (chain and blade) that the tensioner usually ends up in the tightest state (backed off) adjustment of the tensioner is just designed to allow for wear in the chain, blade and guide. Will be checking tensioner adjustment again after 500 miles.
Thanks for everyone’s help
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I don't have much of an opinion on the design of the CB500/550 tensioner, but the quality they came in, is outright flimsy. It's the part I hate most. Have a look at the pic in reply #8 and you'll understand how little it takes to derail things. Hopefully an aftermarket one is better.
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The gearing to the screw head (that you must not turn) is very coarse so the entire rotation of the screw between fully retracted and extended to the point your chain is knackered is probably only about 60 deg CCW. 1/6 of a turn.
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Honda didn't offer much help as far as the do's and don't's. In Holland in those years Honda dealer mecs were invited once a year at Honda The Netherlands for instruction. No doubt they have had additional instruction on how to treat the camchain tensioner. For us, amateurs, Honda left a puzzle. Honda never made clear whether adjustment was best done with the engine cold or warm. Also the instruction varies. Compare p.48 of the Owner's Manual CB500K1 https://www.honda4fun.com/dwnload/Owners-Manual/CB500-K1-Owners-Manual.pdf,
p.12/13 of the Shop Manual Honda CB500-550, http://manuals.sohc4.net/cb500/service_manual/HSM500550_1.pdf
p.68 in the CB550K3 Owner's Manual https://www.honda4fun.com/dwnload/Owners-Manual/CB500K-CB550K-Owners-Manual.pdf and
p.3-7 in the manual for the CB650 https://cosky0.tripod.com/imagelib/sitebuilder/misc/show_image.html?linkedwidth=actual&linkpath=https://cosky0.tripod.com/sitebuildercontent/sitebuilderpictures/page03-07-cam-chain.jpg&target=tlx_new.
Four different methods...
Oh... and I do have an opinion on the design. It's poor. I've never managed to do more than 45.000-50.000 km with one.
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I'm on the same camchain tensioner from new, blades been replaced more than a few times along with the damper rubbers at either end. It's done around 147000 miles at present and it will be refitted once the engine comes apart this summer. It's a matter of how you use it IMO. Do it right and it seems to last forever. I do seem to recall replacing the spring once but that might be the K reg bike not the L reg.
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Well... I certainly can learn from you. IMO the whole thing lacks robustness and a mistake is just too easy to happen. If even the mere replacement of the locknut by a new one, is a risky affair... I sure hope there will be an aftermarket one that's more robust. Pro mecs have also struggled with it. Honda The Netherlands gave them extra instruction, but left us amateurs the puzzle of four different methods.
I suppose the method in the CB650 manual is best. What would be best: engine warm or cold?
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Dont matter just do it the right way and dont force the sxcrew and there is no problem, only problem with nut is if s~mebody has forced the screw and splayef the end open which is again bad operation by an idiot owner and nothing to do with Honda
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Thanks for the compliment, but mecs here were of a different opinion. They also told me the 5000km interval of adjusting the tensioner (as in the maintenance scedule) is a joke. It needs to be done much more frequently. In my 100.000 km experience at least every 1500km. They also strongly advised not to do it the way described in the K3 Owner's Manual. Two of the mecs had a CB500 themselves.
A screwdriver can be needed to keep the bolt in position while tightening the lock nut. Even the slightest and unnoticed widening of that gap may later - when you have completely forgotten about it - hinder replacement of the nut by a new one. When you then start to wonder, why the nut doesn't come further of, it's already too late and the damage is done. If that can happen, in spite of warnings, I'm sorry, but then the design is poor. Yes, lesson learned, but at what cost...
Never damaged a tensioner yourself, Bryan?
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Ive fixed a few but never damaged one, i found the 3,000 mile service ok if you made surr the front run was tight so all the slack in rear and that was advised by the UK travelling Honda techs, we didnt get annual training
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IMO the design is too close to the racers our models derived from. The CB350F tensioner was even worse. Before models came to the market, they were thoroughly tested ofcourse. But what Honda never was able to test is, how things would be after six months of inactivity. If you try to adjust a CB350F tensioner, after six months of hibernating, well, good luck!
The method you was told, was also the instruction Dutch mecs received from Honda The Netherlands. The public was never informed though. That method is good, be it that the mec I've learned it from, always asked a collegue to assist for a second. Amateurs like myself I'd advice to do it with plugs removed, for a good feel, because the compression could fool you. Or do it as described in the CB650 manual, turning the crank extremely slowly, so you are sure.
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Why are you not supposed to turn the engine with the big nut at the points? I know it's been mentioned before but can't find anything relating as to why not.
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Peter, I've been using that nut to turn the crank for the last 42 years. What you refer to is the usual mass hysteria in the international forum, once one high in the pecking order has warned against it. That will be echoed by the others. Ofcourse you can do it wrongly, but if you use a T-handle like shown below, you can even do it when the engine is red hot.
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The reason why is that with plugs in you can easily break the "ears" off the cam and elongated the hole the locating pin fits in. I have seen both but never done it myself.
With no compression (plugs out) it ought to be safe to use BUT putting that caveat in an explanation people either dont read, dont understand or dont care.
How many owners of cars with broken cam belts have ignored the OR FIVE YEARS bit
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The reason why is that with plugs in you can easily break the "ears" off the cam and elongated the hole the locating pin fits in. I have seen both but never done it myself.
With no compression (plugs out) it ought to be safe to use BUT putting that caveat in an explanation people either dont read, dont understand or dont care.
How many owners of cars with broken cam belts have ignored the OR FIVE YEARS bit
What do you mean by "breaking the ears off the cam" please Bryan?
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There are 2 ears on the advance/retard mechanism Ted, these are so the nut locates properly and allows the nut to turn the mechanism if required, if you force the nut there is a chance these will shear off.
I regularly used to use the nut to turn the crank, hard not to when your watching the points for opening/closing etc but I always removed the plugs first so the effort required was much less.
I ditched the bike one night coming down a steep hill with a 90 degree bend at the bottom, the council had tarmaced over cobble stones and they was an area where they were exposed, I didn't see it in time and being cranked over to the max the bike just went away under me, skipped up a kerb island, through a bus shelter, luckily one of those sheet metal types, scattering the waiting queue who were luckily watching me rag the 500 down the hill (I was young and an idiot), fell off the kerb island into the bus stop and stopped. I was already walking toward it before it stopped, picked the bike up and the points cover was mashed flat, removed that and spotted the advance/retard mechanism was bent to hell and back, removed the bolt, smashed it flattish and reassembled everything whilst bleeding all over the floor, bike started on 2 cylinders but got me home. Second hand mechanism later and good as new, really built these bikes to take punishment. The ears were still ok though so it takes some force to break them off.
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The steel of the ears is much harder than that of the WASHER,SPECIAL (Hondaspeak for that nut, PN:30233-300-000). I've learned about risks turning that nut on the CB750, but the CB500/550, mwah, if you do it with care...
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Its is harder, but they still break off seen quite a few after owner maintainance done wrong.