Topic: Best way to adjust cam chain?

[bryanj]

I know its sounds odd but if you turn the engine over using your hand on the kick start you can "feel" when the engine is just about to move, this tightens the front run of the cam chain and puts all the slack in the rear so when you loose the locking mechanism all the slack will disappear AS LONG AS your mechanism is not frozen and not at maximum I.E. cam chain worn out. You have to keep the weight on the kick start to stop the crank rotating backwards and loosening the front run.

I know this sound complicated but believe me it isn't and one person can do it as long as you make sure the locking device(bolt, nut or both) is free to move first

[Keith]

I wouldn't do it. Yes, on a 750, you have to pull the engine to take the head off...

[evinrude7]

I know its sounds odd but if you turn the engine over using your hand on the kick start you can "feel" when the engine is just about to move, this tightens the front run of the cam chain and puts all the slack in the rear so when you loose the locking mechanism all the slack will disappear AS LONG AS your mechanism is not frozen and not at maximum I.E. cam chain worn out. You have to keep the weight on the kick start to stop the crank rotating backwards and loosening the front run.

I know this sound complicated but believe me it isn't and one person can do it as long as you make sure the locking device(bolt, nut or both) is free to move first

Bryan, so loosen the bolt and lock nut first then turn the motor with the kick?

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[bryanj]

No Make sure the bolt and nut can be loosened easily but leave nipped up before turning then its easy to move bolt/nut with one hand whilst other is holding kick start.

Not easy to write English that is understood on both sides of the pond

[rocks]

i'm thinking of giving this "while running adjustment" a shot before i head out for a quick job in the am.  get the bike idling, warm and loosen the lock nut and bolt then just cinch it back up?

edit: if it doesn't quiet down i'll do it the way uk honda mech recommends.

Adjusting it with the engine running won't tighten the chain. If you put a screw driver (I put Allen key)behind the tensioner you will feel the plunger kicking back. If you apply pressure to the plunger you will end up with no noise, but that isn't good either.
The manual suggest to adjusting it when #1 cylinder is at TDC and move the crank 15 degrees. The reason for this is the cam has most of the slack in the back with this position.
Using the kickstart  might or might not do it. It doesn't hurt to try it.
Now, if you adjust the cam time while the engine is running and you chain is too loose you might skip a tooth or two and you end up with bent valves.

The noise could also be you primary chain. Run the engine, put to gear, release the clutch just a bit until you feel the engine is about to roll. If the noise still there then it's the timing chain, if it quiets then it's you primary chain.

[gtmdriver]

Just to add another variable, should the adjustment be done with the engine hot or cold?

I've always set me CB350F cam chain with the engine idling as described in the Honda and Clymer manuals but also with the engine hot.

When it starts up from cold the cam chain is noisy but this disappears as the engine warms up. I am therefore wary of making the adjustment with a cold engine in case it runs too tight once the engine is hot.

[evinrude7]

Just did mine the way Bryan suggested and i warmed the bike up first. Worked well. More quiet but not too quiet.

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[bryanj]

And did you need a mechanically trained spider?

[evinrude7]

And did you need a mechanically trained spider?

no sir.  worked out fine.  the trick was to pre-loosen the lock nut to give room to cinch up the bolt.  thanks.

[markreimer]

Great timing on this thread. I just adjusted my cam chain yesterday as per the manual, 15 degrees past TDC on #1. I loosened the tensioner bolt, didn't hear or feel the tensioner snap into place, then tightened it back down. I suspect my chain was already in the right place and didn't need adjusting.

It still sounded a little bit too noisy to me after, so I tried the 'running' method. As soon as I loosened the bolt holy smokes did it get noisy! It was not at all suitable if I had just tightened it down and called it a day. I can also confirm what was said before, if you put light pressure on the back of the tensioner bar (this is a cb750 by the way) you can feel the tensioner pulsing in and out rapidly. I applied gentle pressure until it sounded like it did earlier and locked it into place. Also I'll note that I rebuild the tensioner last year with new OEM rollers and cleaned the spring mechanism. My tensioner is in good shape with good spring pressure, so I'm not sure how the running method would work. Maybe I have a pretty stretched chain compared to some and it's more difficult to tension?

I think I'll go back and try the kick start method, that makes a lot of sense to me. I know these engines are relatively noisy compared to some, but I'm hoping to get it at least a little more quiet. Though there may be no point, my clutch rattle still makes the bike sound like a cutlery drawer being dumped on the ground 

[Deltarider]

Why Honda in the CB500/550K3 Owner's Manual suggests adjusting the camchain dynamically, remains a mystery to me. P.68 http://www.honda4fun.com/pdf_libretti/500/CB500_550/CB500_550_06.pdf

[PeWe]

Why Honda in the CB500/550K3 Owner's Manual suggests adjusting the camchain dynamically, remains a mystery to me. P.68 http://www.honda4fun.com/pdf_libretti/500/CB500_550/CB500_550_06.pdf

Maybe the Honda Tech guys have done it with a harder spring? Or with a new chain that will not rattle anyway?

[Deltarider]

Maybe the Honda Tech guys have done it with a harder spring? Or with a new chain that will not rattle anyway?

Could be, but the parts involved, were still the same as in the very first CB500...

[markreimer]

You know, I think I actually have done the dynamic tension method on my first K4 engine with ok results. My engine currently is a donor bottom end with my original top end (cracked an engine case, made a franken-engine using a spare bottom end, meaning it now has a different cam chain). Maybe the condition of the chain plays a big role in whether you can do this with the engine running. Mine sounds nasty if I just loosen off the tensioner while it's running. Actually so does my cb350F, and it only has 6,000km on the engine, most of which I put on last year. It needs gentle pressure on the tensioner as well.

[jakec]

I just tried two methods on my 400, kickstart method, and when I didn't hear any movement, I also tried 15 deg. past 1.4 TDC. In both cases I didn't hear any movement. Although I may just not need any adjustment as the engine sounds fine. I also stuck a screwdriver on the end of the piston and pushed rather hard and didn't feel any movement. So it's either totally fine or already seized, lol. BTW, the maintenance interval on these is insane, at 500 miles that's at least once a month in the summer or every time you go on a long weekend...

I am rather obsessive about the tensioner because I have already have one TTR 400 tensioner become chewed up and seized, and this is with normal maintenance. I'm on my second tensioner replacement now.

[Phoenix]

Last time this came up I got yelled at for suggested the dynamic method.  It ran quietly for years with no problem.  With a warmed up engine,  I had my son run it up to 2500 rpm.  I pushed the rod in with a hex key until it ran quietly.  While holding it in, I tightened up the nut.  Done.  Of course you do this after adjusting all the other aspects.

[BenelliSEI]

The pressure applied by the tensioner is limited (by design) to the pressure generated by the spring. Surely “pushing on it” means the pressure is over spec and you can expect rapid wear on the internal components (tensioner wheel and slides)?

Why not just follow the directions in the Factory Workshop Manual?

[M 750K6]

My tensioner wasn't moving, totally stuck. I removed and polished it, until it moved smoothly on the spring. This may be the reason some of the attempts using the factory service manual method aren't working.

Bryan's kick-start method looks like an easier way, avoiding having to remove the points cover and go to 15 degrees ATDC (I seem to recall, when no.1 is on compression?), but it still requires a freely moving tensioner.

I traced the new gasket onto some gasket paper, so I don't need to wait for a replacement in future. I will check it is still free, probably every other service.

[HondaMan]

I can synopsize the 750's best-way:
1. Remove the #4 intake valve tappet cover.
2. turn the engine over slowly with the kickstarter until this valve just starts to open - you'll see the rocker tip heading down.
3. Release the tensioner's nut and bolt, then press into the hole on the back of the tensioner if you didn't hear it move (they are barely audible when they 'jump' to tension). Then stop applying the pressure, if you're doing it this way.
4. Retighten the lockbolt (gently, it's just holding the rod) and locknut. Put the valve cap back on.

[jakec]

The pressure applied by the tensioner is limited (by design) to the pressure generated by the spring. Surely “pushing on it” means the pressure is over spec and you can expect rapid wear on the internal components (tensioner wheel and slides)?

Why not just follow the directions in the Factory Workshop Manual?

With the keeper bolt loose, the tensioner will move back to the correct spot before tightening the keeper bolt. It's only to test for any movement at all.

[HondaMan]

Why Honda in the CB500/550K3 Owner's Manual suggests adjusting the camchain dynamically, remains a mystery to me. P.68 http://www.honda4fun.com/pdf_libretti/500/CB500_550/CB500_550_06.pdf

I'm with you... 

[38rudge]

No Make sure the bolt and nut can be loosened easily but leave nipped up before turning then its easy to move bolt/nut with one hand whilst other is holding kick start.

Not easy to write English that is understood on both sides of the pond

So doing it this way would imply that you are not concerned with the crank position or any particular firing position and that by just applying tension to the kickstart lever in any crank position will be sufficient to provide the correct camchain tension by releasing and then nipping up the tensioner bolt?

[bryanj]

Correct, all you are doing is ensuring that the crank is pulling the front run tight to allow the tensioner to take up any slack.

On an asside you can tell if the camchain on a 750 is worn out by removing the tensioner assembly, 3 bolts, the with it in your hand loosen the lock bolt and see how far the plunger moves, if not far it needs a new chain. There is a "step" front and back of the rod flat surface to stop overtravell, if you undo the bolt and remove the rod you can frequently see witness marks where the lockbolt has been tightened and the bolt can, and will, find these marks again meaning tension is not correct.
It can be advantageous to carefully dress out these marks

[ofreen]

It can be advantageous to carefully dress out these marks

And I know you know, if there are marks or divots, the bolt is being over-tightened.  Some people apparently think the bolt needs to be reefed on to do its job.  I used to see the same thing with the KLR650 "doohickey".  I always believed the tensioner breakage problem on those was in large part do to over-tightening so much that the admittedly cheaply made part was damaged to the point of breaking.

So doing it this way would imply that you are not concerned with the crank position or any particular firing position and that by just applying tension to the kickstart lever in any crank position will be sufficient to provide the correct camchain tension by releasing and then nipping up the tensioner bolt?

I would also add that while doing this it works best if you are bumping the engine up against compression.

[Deltarider]

I wonder... is there anything against declaring the method in the CB650 shop manual* safe for all CB Four models?
     Loosen the camchain locknut.
     Tighten the camchain locknut while slowly rotating the crankshaft clockwise.
*p.31 in: http://manuals.sohc4.net/cb650/service_manual/SM65079_03.pdf