Rattle at 3,000-4,000rpm

Hey all. My 82 550 has a nasty rattle at about 3,000-4,000rpm. Above and below this she sounds great. Engine runs strong, but this sound is driving me nuts. Anyone got any ideas. I just tried adjusting the timing chain tension and it didn't help. Also when the bike is cold, or it is raining while I am riding it doesn't make the sound, but once the bike has warmed up and if it's not wet it rattles like mad.

 

I'm not an expert on the 550, but I do know it has a chain drive. When's the last time you cleaned/lubed/adjusted/replaced the chain and sprockets? Checked alignment?

If you replaced the sprockets and chain recently, there may be a shim that needs to be taken off/adjusted for the new sprockets to line up correctly.

I'm not sure though...someone with a duck avatar will be along shortly, he probably knows the most about the 550's.

 

The most unruly harmonics on the 550 come into play around 3800-5000rpms, but if the bike is tuned right were only talking about a little more buzz coming through than otherwise - on my 550 it's barely noticeable.

You need to give some more information for advice. Describe in greater detail what you mean. Is the rattle in your bars, in the frame, coming from down low? Is it changing the way the bike rides, power application? More details and we can figure it out. Also any modifications to your bike? What maintenance have you performed on it? If you haven't done any (besides oil change) or can't be sure anyone else has-it's time.

 

lol tskaz (duck avatar). I don't think hes talking about a little vibration in that RPM range, I think "nasty Rattle" is probably something else. Maybe tskaz suggests or camchain tightening needed, yes....the duck would be the guy on this one....lol

 

ha ha, duck. I been outy for a little bit and soon as I get back you guys still crack me up.
I'm no duck (not by a long shot) but Im thinking primary chain maybe, first question would be of course hows the valve clearences and how smooth is the idle? does the idle lump?

 

If its a nasty rattle, it might be a baffle partially or completely broken loose in the muffler.

 

Very good idea. Depends on the other information about the bike.

My 550 currently has no baffles at all - straight pipes. Before tuning things up, I experienced a decently "nasty buzz", but that was at every RPM.

I agree, more info...

 

Enough with the Duck avatar references already.

Stuff that can cause your symptoms:

-Head pipe loose at head or at collector. At one point I thought my collector box was starting to "break up" internally and it turned out my #2 headpipe was loose at the collector; made one heck of a racket.

-Collector box mounting rubbers deteriorated, collector box rattling against frame/mount, underneath.

-Collector box slightly out of position, allowing chrome "vanity shield" on either side to contact rear peg mounting brackets.

-Muffler loose at collector box (but tight at its mount.)

-Baffle broken loose inside collector box or either muffler.

-"Vanity shield" mounting clamp (welded on, but clamped too, never quite understood that) broken or broken loose.

-Of course check your chain and sprockets, chainguard, etc., as suggested above. Make sure the chainguard isn't loose at the front end.

-And here's one I would have never thought of had it not happened to me: The rubber mounting "cradle" for my safety relay (which is in a METAL can) broke, allowing the relay to hang down and rattle/buzz against the top of the valve cover. Not easily spotted, as it's up under the tank.

The RPM related "buzz range" of the 550s is generally from around 4500~4800 RPM, if it goes away over 4 grand, it sounds like it's something other than just the normal vibratory range.

 

So a little more info. I bought this bike in march with around 45,500 miles on it. I changed the oil within the first 200 miles of getting it, and then 1500 miles later changed it again with full synthetic. I looked on line before and read that it should run 20W50 but i'm starting to think that was the wrong thing to put in.
The carbs need to be taken off and gone through, I have just been using it as my daily driver so I didn't want to take it apart. It had sat for 18 months before I bought it.
I don't know when the valves were adjusted last, but I have adjusted the timing chain, and the drive chain.
The idle isn't smooth. Once you get it above about 1500 it is smooth up until the rattle starts. The rattle is audible and you can feel it in the handle bars. I have tried to listen to it when the bike is parked and it just doesn't quite sound the same, but it sounds more like it's coming from the engine than the exhaust.
Hopefully this helps, if you need anymore info just let me know.
Thanks everyone.

 

Ahhh the mighty DUCK!!! c'mon Fitz, this is great stuff don't be embarrassed.

 

One way to find those rattles is to get a mechanics stethescope from the auto parts store (cheap). It'll have a steel probe on the end instead of the diaphram like the nurses ones do. Touch that probe to things on your bike while reving it up to the noise making RPM and probe around till you find it.
Some folks will stick the handle end of a screwdriver to their ear and touch the metal end to the bike...but it's much easier with a stethescope.
Those little chrome shields on the exhaust pipes (if you have them) are a good source of a nasty vibration. I had the mounting bracket break off of one on me and I thought for sure I had serious internal damage...
On my '82 XJ1100, the headlight mounts rattle a bit at certain RPMs too.

 

That's DEE - YOU - CEE - "uck" :lol:

You can go after all the loose items outside the motor with a bunch of wet rags, then go for a short ride. (be thorough), then if it still rattles, it's inside.

 

That's "Mister Dodgers, Sir." http://www.spaceref.com/news/viewpr.html?pid=11681

Let's talk about the 550s and their inherent "rattle."

The 550 has a "true" primary chain; this is to say the primary chain provides the drive from the motor to the clutch/transmission. This primary chain is a wide, HY-VO chain that is tensioned automatically by an hydraulic tensioner operated by engine oil oil pressure. As a result, it will be loose at low RPM/low oil pressure moments, but should be fine as soon as the RPMs rise.

The chain itself however, is not what rattles.

What rattles is the clutch and transmission if there is any "unevenness" to the pull on the primary chain, especially at idle. Unforunately, one inherent trait of a 4-cylinder that's out of tune is a lump-lump-lump idle. The smoother you can get a 550 to idle, the less the clutch and trans will rattle. At idle, anyway.

Now let's bring oil into the picture. You said you switched to "full synthetic" 20W50. There's nothing wrong with running 20W50; however it needs to be motorcycle oil NOT automotive oil.

If you put car oil in it, the first thing you need to do is change the oil again.

Use motorcycle oil; Castrol 4T is widely available. 20W50 is fine (unless it's really cold out. You don't have a location in your signature.)

Then: Don't make assumptions based on what it "sounds like." Carefully check the items I listed.

Inspect the drive chain, check its tension, ensure it's properly lubricated, and check it for wear. If you don't know how to do that say so and I'll be happy to explain.

It could also be something ridiculous like the clutch coming loose on its shaft; I wouldn't even suggest it had it not happened to me on one of my 550s (silly PO.)

Noises and vibrations can fool you, big time. The range at which you're getting this doesn't correspond with the natural "buzziness" of the 550s, unless yours is HORRIBLY out of tune; I suspect another cause.

This needs to be investigated before something "lets go" on you.

 

Welcome.

If the sound is a true rattle then most of the causes have been
covered.
If more of a buzz-and it can be quite loud- then check
the fins. There should be little rubber "absorbers" placed in
between them.
I've run my bike without them just to feel the diff and it was
very loud and anoying.

As far as oil-the full synthetic is great on the new bikes but can cause trouble for us. Stick wth a good quality oil made for bikes and you'll
be fine. I use castrol 20w50 4T in the summer and 10w40 in winter.

 

At first I was going to suggest that you check the mufflers and the collector box and make sure that everything is tight. It is often the case where something at one of the clamps will quack. Oops, I mean crack. It is also quite possible that a baffle or something can beak. Oops, I mean break.

But, others have already told you to check there, so I'd have to agree with those that are suggesting it may be something inside the engine. Your own comment seems to indicate that you're leaning that way too.

Do check the kickstand, though, and make sure that is not loose.

As you're checking the engine, listen not only for the rattle, but listen close and try to either hear or eliminate the possibility of a metallic wing. Oops, I mean ring. If you hear any hint of metallic ring, that's not good.

Hopefully you can narrow it down more, and give us more detail. Oops, oh wait.....yeah, i meant deTAIL.

We're here on the web (umhmmm, yup....intended) to help you avoid having a costly bill. (.....and another.....)

I'd better stop now before someone throws something at me and I have to
...................DUCK.

Dave Fox

(hmmm........just noticed in all the bikes I have, I have no DUCKati's.

 

Oh ha ha Dave; did you sit up all night thinking those up?

I thought of something else too: I got my '83 550 with a bent clutch basket. The bike had fallen on its right side hard enough for the brake lever to punch through the clutch housing and mash into the clutch basket enough to bend it. The whole clutch assembly was "orbiting" as a result, causing a really pronounced vibration that increased with engine RPM.

Also nearly as obscure as the clutch coming loose, I would think.

 

I read through the whole forum again.........I'm gonna suggest that you go back and look at the exhaust collars at the front of the engine and double check them. See if any of the studs are broken and that you have a loose exhaust pipe. I've had collars get loose numerous times, and it can sound like the whole motor is about to blow up. I would only hear it after the engine got pretty good and warmed up. Tighten the nuts just a smidgen and it would be fine.

Keep letting us know every little thing that you do so that we can eliminate some things and pinpoint others.

dave