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Offline hummbug

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Tick Tick Boom??
« on: October 28, 2009, 03:42:43 AM »
I have read a few posts on this subject and none of them sound particularly positive so I'm starting to worry slightly...
71 CB500 - 26,000miles
It has developed a ticking (more like a metallic rattle) at about 5500k RPM. It continues at any revs after that too. It's coming from the right side of the top end - but I wouldn't rule out the points cover area either.
The closest thing I can relate the sound to is that of the dry clutch on a Ducati. It's not as nice as that and seems out of place on a bike with a wet clutch but it has the same characteristics. It's difficult to hear whilst riding and it is difficult to hold the bike at high revs whilst in neutral - it seems cruel - to the bike AND the neighbours...

The other thing I noticed a couple of weeks back, after I had topped up the oil (possibly too much) was that oil had blown out of all 4 tappet covers at some point -  I suspect at around 9k RPM one day.   ::)

The two things seemed to come at the same time.

There seems to be no loss of power but I am reticent to take the bike past 5k rpm at the moment in case I am about to own a very heavy push bike.

Help save my bike - it's about to turn summer here!!


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Offline GoatBaSS

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Re: Tick Tick Boom??
« Reply #1 on: October 28, 2009, 05:05:22 AM »
You might want to drain the oil and start over. I am at a loss as I am very tired and not able to think. But I do think to much oil is bad (thus the tappet covers).
First off dont panic...

Double check your points cover. One of my bikes fell over and I dented that cover, rattled worse thatn a can of empty spray paint. Look on the inside for rub marks, check gasket just to rule out....
« Last Edit: October 28, 2009, 05:17:53 AM by GoatBaSS »
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Offline Johnie

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Re: Tick Tick Boom??
« Reply #2 on: October 28, 2009, 05:09:12 AM »
Not sure about the 500, but the 750 had cases of loose valve adjuster nuts hitting the top of the cap.  Might want to check that to at least rule it out.
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Offline KB02

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Re: Tick Tick Boom??
« Reply #3 on: October 28, 2009, 05:16:49 AM »
Quote from: Johnie on October 28, 2009, 05:09:12 AM
Not sure about the 500, but the 750 had cases of loose valve adjuster nuts hitting the top of the cap.  Might want to check that to at least rule it out.

That was my first thought, too. After that I thought about a primary chain tensioner.
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Offline Dirtbag

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Re: Tick Tick Boom??
« Reply #4 on: October 28, 2009, 06:42:34 AM »
I guess cam chain slappy around like a loose meat sammich.
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Offline grumburg

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Re: Tick Tick Boom??
« Reply #5 on: October 28, 2009, 08:00:05 AM »
Cam chain tensioner?  ??? Anything over 20k miles on the original is borrowed time.
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Offline hummbug

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Re: Tick Tick Boom??
« Reply #6 on: October 28, 2009, 04:40:44 PM »
So now I have a project for the weekend!
I will check cam chain tension, remove tappet covers and check gaps....hopefully there is some improvement.
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Offline TwoTired

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Re: Tick Tick Boom??
« Reply #7 on: October 28, 2009, 06:03:11 PM »
Have you checked for cam cover rocker shaft bearing wear?

Have you localized the source of the ticking?

Btw, I have over 40,000 on a cam chain tensioner, and it is still working.  It's still inside the engine, so I can't see just how worn the shoes are.
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline hummbug

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Re: Tick Tick Boom??
« Reply #8 on: October 28, 2009, 10:05:32 PM »
I haven't done either of those TT. I am a bit out of my depth when it comes to the more complicated mechanical processes but I will have a read up in the manual.
Any suggestions for localising a sound within the engine when the only time I hear it is whilst riding?
 I see a man with no helmet riding fast down the road with a long tube against the rocker cover...potential deadly riding situation!!

I might have to blast the neghbours for a few minutes to get a proper listen.
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Offline TwoTired

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Re: Tick Tick Boom??
« Reply #9 on: October 28, 2009, 10:31:11 PM »
If it is only doing the noise while riding and not while revving in your garage, then look toward the drive chain/sprokets.
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline hummbug

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Re: Tick Tick Boom??
« Reply #10 on: October 28, 2009, 11:07:36 PM »
I'm pretty sure it's not that -  I just haven't held the engine above 5500 RPM whilst in neutral.
Tests to come...
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Offline hummbug

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Re: Tick Tick Boom??
« Reply #11 on: October 29, 2009, 12:44:35 AM »
hmmm - could this be it??

I took off the far right side tappet covers - front looks good.
Rear looks like this....

CRAAAAACKK...

« Last Edit: October 29, 2009, 03:21:05 PM by hummbug »
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Offline hummbug

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Re: Tick Tick Boom??
« Reply #12 on: November 05, 2009, 04:19:58 PM »
So...after replacing the cover with a new one it has become apparent that the tappet is hitting the cover at anything over 5500 RPM. Hence the cracked cover and the noise.

Could my gaps be so far out that the tappet hits the cover like this? Or is the problem more likely to be down further?
I did do a quick check of the gap with the gauge I have - it didn't seem out of spec but the guage didn't bend well enough to get a proper feel for it.

Aside from this the bike is running well.
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Offline w1sa

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Re: Tick Tick Boom??
« Reply #13 on: November 05, 2009, 04:52:00 PM »
The valve seat might be suffering some slight recession after 26000miles. This allows the valve to seat deeper in the head and therefore raises the valve stem closer to the cover.
The overtensioning of the cover to try and compensate for worn seals might also contribute to the problem.
You may be able to alleviate/eliminate the immediate problem by removing the tappet adjust screw and file/grind some of the slotted end.
Obviously you run the risk of reducing the slot/depth/strength by too much removal of material.

Edit: Some wear in the rocker arm/shaft joint and even the arm's slipper end could compound the problem
« Last Edit: November 05, 2009, 05:05:39 PM by w1sa »
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Offline jhasewhite

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Re: Tick Tick Boom??
« Reply #14 on: November 05, 2009, 05:28:38 PM »
Could the tappet cover crack from simple overtightening? Two of mine are cracked and I think its just a torque issue from the previous owner.  Or is it???  maybe you just figured out that horrible ticking noise!!!???


1976 cb750f about 32 thou miles.
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Offline TwoTired

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Re: Tick Tick Boom??
« Reply #15 on: November 05, 2009, 05:40:14 PM »
I don't see why the 500s wouldn't have the same problems with cam covers that the early 550s had.
See..
http://forums.sohc4.net/index.php?topic=20408.msg212239#msg212239
« Last Edit: November 05, 2009, 09:53:38 PM by TwoTired »
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Lloyd... (SOHC4 #11 Original Mail List)
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Offline w1sa

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Re: Tick Tick Boom??
« Reply #16 on: November 05, 2009, 06:09:04 PM »
Quote from: TwoTired on November 05, 2009, 05:40:14 PM
I don't see why the 500s wouldhave the same problems with cam covers that the early 550s had.
See..
http://forums.sohc4.net/index.php?topic=20408.msg212239#msg212239
I wasn't thinking of the shaft's (end) mounting so much as the working tolerances in the arm sleeve/shaft etc. They can develop wider and out of round shape. They still function well, but the uneven wear occuring at the pivot/load point in the sleeve, still means that the arm itself progressively sits higher (as minor a measurement, as that might be)
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Offline hummbug

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Re: Tick Tick Boom??
« Reply #17 on: November 05, 2009, 07:39:17 PM »
It's not an overtightening issue - I have put a new cover on and the noise remains.
As for the rocker cover - as TT states, if it's not one of the 550 covers then it's unlikely to be that particular problem.

Valve seats huh?....sounds serious. As I said earlier - I'm wet behind the ears when it comes to the more complex mechanical issues but I'm willing to have a crack at it with the guidance of the forum...


What would be my best course of action from here?
Ignore the noise? Make a new inspection cover with a higher clearance? Tear down and rebuild? Ride under 5500RPM ALL the time?

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Offline TwoTired

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Re: Tick Tick Boom??
« Reply #18 on: November 05, 2009, 09:58:12 PM »
I mistyped my response above and have corrected it.

The rocker arm shafts are not pined down in the early 500/550 rocker covers and the steel shafts may turn in the soft aluminum cover causing oblong wear patterns.  The forces push the entire shaft higher in the cover where the rockers eventually hit the inspection covers.

Better revisit the link I posted and determine if that problem has occurred on your engine.
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline hummbug

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Re: Tick Tick Boom??
« Reply #19 on: November 06, 2009, 01:25:14 AM »
I pulled the covers off and both shafts on both sides were snug and there are no gaps. Oil came out of the little holes though - not much...

I ran the engine to 6500RPM  with the inspection cover unscrewed to give more clearance - no difference.
I adjusted cam chain (as per manual) - no difference. I would like to try this again though, not sure there was any adjustment going on when I did this...
Loosened and re-tightened all the header pipe nuts - no difference.

Next step is to do full oil change and see what I find.

I may also pull the horn off to make sure it's not something loose inside there!!! When I put my head toward the front of the tank to have a listen to the rattle it seems to be coming from that area. I still think it's something to do with the tappets...
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Offline TwoTired

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Re: Tick Tick Boom??
« Reply #20 on: November 06, 2009, 09:23:03 AM »
As means to localize the noise, get yourself some aquarium tubing, 2-3 ft long.  Rest one end in your ear canal, you use the other end to probe for noise.  At what point is it the loudest?
This is a poor man's mechanics stethoscope.
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline hummbug

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Re: Tick Tick Boom??
« Reply #21 on: November 11, 2009, 12:54:23 AM »
Alright, so here is where I reveal myself to be a total nuffy...

I did a full tappet adjustment (my first ever) and took the bike for a test run. Rattle still there. Damnit!!
Got about half a mile from home and it dawned on me...as I looked down to my right hand it was there clear as day! The brake lever was rattling around like an old tin of coins when I hit 6000 RPM.

There is a sense of relief but also of regret that I have now truly revealed myself as the biggest knob on a Honda... :-[

Thanks for all the suggestions and it was good that I went through the process of the tappet adjustment. Now I just need to work out how to do it better. I followed the manual to a T and found that I wasn't getting movment in the tappets as uniformly as it suggested.

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