Topic: Did valve adjument, cam chain adjustment, and still getting clanking sound

[daewon774]

I just got a 76 CB550 a few months ago.  It rides great and the motor seems sound.  I heard a slight clanking sound, the type of sound you get from a motor that needs the valves adjusted.  I did the adjustment today along with the cam chain tensioner and it's still there.  Bike has about 8000 miles.  Is this normal for these bikes?

[Untold]

Did you synch the carbs?  That can cause some rattly sounds.  Although I just recently did a full tune-up on mine, and it still makes some noises.  It's the bike showing it's personality.

[crazypj]

If it gets quieter above 3,000 rpm you can pretty much bet it's carb sync (or if it quietens down as your pulling away from standstill)
If carb sync doesn't cure it, there is a possibility of primary chain wear although that's more of a 'thud'

[toytuff]

I had my clutch apart thinking my noise issue was in that area. Everything else to spec. Even held the long screwdriver method all over the motor to my ear.

I think it's the primary chain which from what I have been told is just the nature of the bike.

tt

[daewon774]

Thanks for the replies everyone. 

The sound is very mechanical.  Can the carbs actually sound like that when out of sync?  And what does 'normal' primary chain sound like?  And is it normal and ok?

Ed

[Duke McDukiedook]

What did you set the cam chain adjustment to? The Honda manual or Clymer?
For the 750 the Clymer manual gets it wrong and that resulted in more noise for me the last time I set my adjustment.

[daewon774]

What did you set the cam chain adjustment to? The Honda manual or Clymer?
For the 750 the Clymer manual gets it wrong and that resulted in more noise for me the last time I set my adjustment.

on the CB550 its a self adjusting tensioner.  Basically you get the motor to TDC for cylinder 1, then loosen the bolt for the tensioner.  It will self adjust after that. 

[Untold]

You're actually supposed to be a little past TDC.  15 degrees I believe.  You go past the T mark for 1.4, then line up the little post with the line.  Check the manual again, it explains it with a picture.

[Untold]

Also, sometimes the self adjuster will be stuck, so I give the screw a little 1/8 turn in each direction a couple of times to loosen it up, then let it do it's job.

[Cqyqte]

Thanks for the replies everyone. 

The sound is very mechanical.  Can the carbs actually sound like that when out of sync?  And what does 'normal' primary chain sound like?  And is it normal and ok?

Ed

Its not that the carbs are making the sounds themselves, the fact that one carb is telling cylinders to run at a particular rpm based on fuel supply and the other carb is say to its cylinders, no run at this rpm.  So the crank is being stressed faster/slower because the two carbs, or whatever number are fighting with each other.  So the motor is being shaken and beat up with every revolution of the crank and whatever can rattle or vibrate can and does.

[daewon774]

You're actually supposed to be a little past TDC.  15 degrees I believe.  You go past the T mark for 1.4, then line up the little post with the line.  Check the manual again, it explains it with a picture.

yup, left that detail out.  I did go 15 degrees past TDC.

[daewon774]

Thanks for the replies everyone. 

The sound is very mechanical.  Can the carbs actually sound like that when out of sync?  And what does 'normal' primary chain sound like?  And is it normal and ok?

Ed

Its not that the carbs are making the sounds themselves, the fact that one carb is telling cylinders to run at a particular rpm based on fuel supply and the other carb is say to its cylinders, no run at this rpm.  So the crank is being stressed faster/slower because the two carbs, or whatever number are fighting with each other.  So the motor is being shaken and beat up with every revolution of the crank and whatever can rattle or vibrate can and does.

Hmm... how can I check this?  Is the only way to see if it out of sync to actually do a vacuum sync?

[Duke McDukiedook]

Yeah, you will need a 4 port vacuum tester to see if the carbs are drawing the same amount of vacuum.
There should be someone around you on the site that might be able to help you with that.

[RFogelsong]

If the carbs don't fix it, how old are your plug boots?  Any arcing?

[Untold]

I see you're in Newton. I'm right over in Somerville and I have a carb synch tool.  Not really a fan of loaning out tools, but if you want to bring the bike by (or I can probably come to you), I'd be down to lend a hand.

[daewon774]

I see you're in Newton. I'm right over in Somerville and I have a carb synch tool.  Not really a fan of loaning out tools, but if you want to bring the bike by (or I can probably come to you), I'd be down to lend a hand.

Untold, that would be great.  Next weekend is actually supposed to be kinda warm.  Mind if I swing by?  I'll send you a PM

[Cqyqte]

If you don't have a set of vacuum gauges you can get close by using the ear and tube method.  Take a piece of tubing and place one end at the edge of the mouth of one of the carbs while the motor is idling.  Place the other end of the tubing close to your ear and listen to the hiss.  Now move the end to the other carb to approximately the same spot as you held it on the first carb and again listen to the hiss.  If the two carbs are in relative sync the hiss from either carb will be the same pitch (musical pitch).  If they are different one high the other lower then they are out of sync.    We used to use this method of balancing Stromberg carbs on British cars back in the day!

[lucky]

I just got a 76 CB550 a few months ago.  It rides great and the motor seems sound.  I heard a slight clanking sound, the type of sound you get from a motor that needs the valves adjusted.  I did the adjustment today along with the cam chain tensioner and it's still there.  Bike has about 8000 miles.  Is this normal for these bikes?

Try this:

Check the valves again but.... If the gap is .003  then try to insert a .004 THEN you will know if you got it correct.

Do the same for the .002 intake. Try to insert a .003 thousandths thickness gauge.
The .003 should not fit,then you know it is .002.

[Duanob]

What did you set the cam chain adjustment to? The Honda manual or Clymer?
For the 750 the Clymer manual gets it wrong and that resulted in more noise for me the last time I set my adjustment.

on the CB550 its a self adjusting tensioner.  Basically you get the motor to TDC for cylinder 1, then loosen the bolt for the tensioner.  It will self adjust after that.

you can also force it a little bit too although not too much. Counter-clockwise will tighten the chain. Hold tension on the adjustment screw while you tighten the nut. I use a 90 degree screwdriver for this. I never trusted the self adjuster to self adjust. Something that old is bound to be a bit stiff or gunked up.

[Eddie]

Hey Cqyqte has a cool idea.... maybe, instead of a vac guage, 4 whistles could be used !
would be interesting to hear.. I know.... a bit out there.

[Cqyqte]

If you are tone deaf, download the guitar tuning app for you Iphone and place your phone at the end of the tube instead of your ear the app will tell you the pitch of the hiss and then just match the pitch to that for each carb.  It works, don't believe me try it and be amazed! 

[lucky]

Hey Cqyqte has a cool idea.... maybe, instead of a vac guage, 4 whistles could be used !
would be interesting to hear.. I know.... a bit out there.

Whistles turned backwards? Also trying to hear whistles over engine noises?
Sounds like being in a band.

[Old Scrambler]

Where do you think the expression 'tune-up' came from?

[crazypj]

Thanks for the replies everyone. 

The sound is very mechanical.  Can the carbs actually sound like that when out of sync?  And what does 'normal' primary chain sound like?  And is it normal and ok?

Ed

 Some bikes sound like a failed big end bearing if one carbs is  even a little out and 3 are 'good' (Suzuki GS1000 for one)

[daewon774]

alrighty... so here we go.  I just did a carb sync.  The carbs were perfectly in sync even before I touched it.  My plans?  Go through an entire tune up. 

To be honest, I can't tell if this is the normal sound of a CB550, but is sure as hell doesn't seem right.  I've had V-twin cruisers, and currently have a Ducati 848 in the stable.  The CB550 sounds WAY more noisy then my L-twin. 

Any suggestions on what to look for or check?  I've done valve clearances, cam chain tension, and as of today, a carb sync.

Any ideas, opinions, or comments or more than welcome.  Spit them out!