Topic: Engine noise help. OP updated

[Tretnine]

My engine started making a ticking/clacking sound this morning that increases in volume with RPMs.   It has been running hot and smokey the last few days as the carbs have been out of tune and we've put a couple miles on... maybe a bit more than a hundred. The motor has 11,000 miles on it total. This morning I reset the needle clips and it idles beautifully but now makes noise. Compression is 80s-90s, so lower than I would like but withing 10%. The #3 cylinder doesn't seem to be firing, but it is getting spark. The #3 pipe is cool while running. The #3 cyl seems to have the lowest compression. I tried retesting with wd-40 in the cyl but compression did not increase. I didn't have any true oil at hand. Help!


UPDATE!
This morning I went out and swapped the number 3 pilot jet, but it has had no difference on the noise/performance. I decided to drive it a bit anyway, and on my way to work heard a rattle and clack like something was being bounced around or rattled out of position, but the loud tapping noise disappeared. It sounded low in the case, maybe a piece of the clutch such as a spring? The clutch works quite well, though. What else could be going on? what else could cause the noise?

ALSO!

The motor seems to idle alright but there is cam / primary chain rattle, it probably needs another sync. The #3 cyl still isn't firing correctly, at least in idle, even with the new pilot jet. so that will need to be addressed syncing. I need to get standard heat range plugs in there, since I have D8EAs in there now. Any other ideas why #3 won't fire correctly? I don't know how to check to see if it's firing at all, but sometimes the idle will jump to about 3k and the motor sounds very nice there. Ideas?

[gtyler5]

I am no expert but here is the first steps I would take, pull the carbs make sure the jets are clean in #3 and all the rest too. after that try adjusting your cam chain they can tick and make a lot of noise. with only 11,000 miles you should have plenty of life left in it but anything is possible.

[TwoTired]

When was it's last 3 month/6000 mile tune up?

What does the inside the gas tank look like?

What does the drainage from the carbs look like?

What do the spark plugs look like?

What mods have been made to induction and exhaust?

[Tretnine]

It was tuned up at the beginning of this season, so about 3 days ago. Before that, I did some work on it last year and it ran strong, but before that I have no idea. I bought it cheap off a guy who couldn't get it to run because he didn't know how to clean points contacts. The gas tank looks terrible, (botched por15 job) but I put a different on on there now that looks clean. I had an inline filter on the bike with the the crappy tank. It had a lot of rust in the bowls without the filter, but the bowls are clean with the filter in. Plugs are varied, but I haven't been able to do any fine jetting/tuning in the carbs since this is the first year I've had it and the first I've really used it. Some are grey and some are black ish, but not bad, by what I've seen on other bikes. Stock 4-into-4 pipes and stock everywhere else - points, cam, carb, etc etc.

Also the carbs have been off many times recently, but I haven't pulled them since the noise started. It really sounds like it's resonating off the crankcase, whatever it is.

[TwoTired]

Hard to diagnose a noise without hearing it.

Some info:
The primary chain connected the crankshaft to the trans.  The 550 has no tensioner there. So, with a bit of wear there is slack to be taken up on one side of the chain or the other, depending on relative speed between crank a trans shafts.  If the speeds change the slack side changes.

For this reason it is best to have all the cylinders firing at the same strength, in order for the crank to spin at a consistent speed.  A weak cylinder will change the crank speed and make the chain "whip" as the slack moves from top to bottom and back.

Also with the crank's speed changes, is gear train "clack" in the trans as the gear tooth contact changes from front side to back side of the gear teeth.  When all these bits are under a load is when the parts are the quietest.

One thing to minimized primary chain noise and gear train "clack" at idle is to be sure the cylinders are all firing evenly.  On a good engine with all bit working, this is achieved by a vacuum carb sync.

Carb vacuum sync is preceded by a complete tune up,  Valve adjust, cam chain adjust, Spark plugs cleaned or renewed and gaped, points cleaned/renewed gaped an timed, and the air filter cleaned as new or renewed.

If you still have a cold head pipe after the above is addressed, and the compression is similar to other working cylinders, then spark is verified to the cold cylinder.  After that, it is a carb issue feeding improper mixture to the cold cylinder, possibly due to a pilot jet blockage.

[fmctm1sw]

My engine started making a ticking/clacking sound this morning that increases in volume with RPMs. 

Did you make sure one of your tappet adjusters didn't come loose and fall off?  Been there done that...  and I was still able to fish it out throught the tappet cover!

[Tretnine]

It's not idling terribly well, but when it is idling the noise isn't audible. The decibels of the noise increase linearly with the speed of the motor. It's also not an idle rattle or clack like you get with a chain, it's definitely a tap, louder than a tap, but speed and volume both increase with RPMs. RIP?

[kslrr]

TT, could this noise be caused by #3 tappets being too tight and a valve not closing completely?

[crazypj]

 If locknuts are not MIA, sounds like valve clearance was done on overlap.
 3 days after service, probably forgot to tighten locknuts on adjusters and one fell off

[Tretnine]

If locknuts are not MIA, sounds like valve clearance was done on overlap.
 3 days after service, probably forgot to tighten locknuts on adjusters and one fell off

Explain please. I'm having problems on #3 and I went back in there to readjust 3 and 4 because it sounds like the sound is coming off the right side when seated... and everything looked fine. What's overlap, precious? Is that when you've got tappet lift when you're set to "T" from another cyl at TDC?

[TwoTired]

TT, could this noise be caused by #3 tappets being too tight and a valve not closing completely?

Is it spitting back into the carb intake?

RE: the overlap question:
A 4 stoke engine sees the piston come to Top Dead Center (TDC) twice during the four strokes.  Once is between the intake and compression stokes and the other in between the exhaust and intake strokes.  Both the valves for a cylinder are on the cam lobes (overlap) between the intake and exhaust stroke TDC, and is the improper point to adjust valve tappets. If adjusted at this point the valve will be too loose and may well result in excessive noise and lock nuts coming loose in the valve train.


I believe you need to localize the source of the noise.  One technique is to use a mechanics stethoscope to listen where it is the loudest.
A poor man's stethoscope can be made fro about 2-3 ft of aquarium tubing, where one end in placed in the ear canal and the other end is used to "probe" the noise source.

At the moment, I'm wondering if you have an exhaust header leak.  These often get louder with RPM.

[Tretnine]

I tried to check the tappet clearances again, but can't find my feeler gauge. The locking nuts are there anyway. I took a video of the noise for your viewing pleasure.

[kslrr]

That is NOT a decent idle.  It's not running on 4 cylinders, it's back firing, it's mis-firing, etc.

[TwoTired]

I think #3 carb has a non-functioning pilot circuit.

Pipe gets hot when revved, exhaust is cool at idle.

I could be wrong.

[Tretnine]

a non functioning pilot circuit doesn't explain (to me at least) the loud clacking noise.  What would cause that? Thanks.

[KB02]

I was thinking exhaust leak at first until TT pointed out that #3 wasn't firing. Could be both combined to form a single noise.

[kslrr]

The clacking is due to what TT indicated before.  Since it's not running smoothly (i.e. on 4 balanced cylinders) the primary chain, cam chain, clutch, etc. are bouncing around.  My CB's have sounded no different when running on less than 4 cylinders.  Get the carbs cleaned, setup and balanced and then move on to other issues.

[Tretnine]

I still have doubts, but I'll give this a shot. I can steal a set of carbs off my other bike and put it on this bike while I'm working and see what happens. Maybe that'll do it. If anyone else has any thoughts I'm exploring all avenues.
 

If the pilot circuit isn't working on the #3 carb, I'll have to pull the slow jet, I suppose. Any tips on how to get that thing out of there? They're always stuck fast.

[Spanner 1]

I'm +1 with TT. #3 pipe is hot only 'cos you revved the motor, but at idle #3 is not running. If you have a short, stubby philips screwdriver you could drop the #3 bowl ( drain it first) and pull the slow jet out with a small pliers. Not that easy, but can be done if only 1 carb needs attention.
Or if you haven't had the pleasure of removing your carbs and cleaning 'em, maybe now's the time!

P.S.... one other possibility is a bad plug-cap which won't pass voltage at low rpm.... swap-out 3 with 2 and see if any different......

[Tretnine]

I just put in a new pilot jet. That had no effect. But, while I was out there with my piece of hose trying to figure out where the noise was coming from I heard something clack and rattle around out of rhythm... and then the noise stopped. SO, there must be something floating around in the crank case or somewhere... maybe?