'85 Maxim with an annoying chirp

Okay, I know that Rick suggested that this could be the alternator bearing but I want to throw this out to the group. When I start my bike there is a fairly loud chirp that occurs on the left side of the bike only. It gets faster as you rev the engine so it's tied into it somehow. If you ask me it sounds like it's coming from the carbs, it really doesn't sound like it's originating anywhere near the cylinders or front cover. It's a constant thing that never goes away and is fairly embarrassing while idling at stop lights. She runs super smooth otherwise and accelerates wonderfully and cruises on the highway with no effort whatsoever...I think she's running the best she ever has. Just there is an annoying chirp.

I did remove the alternator cover, which proved a challenge as I had to disconnect the stator wire from behind the rectifer to get it to slide out so I could examine the shaft. Then didn't realize I tore the gasket around the rubber grommet that holds the stator and brush wires. But it all looked great in there....there was some buildup of dust on the copper plate that the brushes rub on but didn't really see any extra rings or anything indicating the shaft was wondering due to bad bearing. I did start the bike with the stator off and it was still chirping but didn't seem any louder than it normally is which you'd think it would be. I wonder if it could be coming from a diaphragm in a carb? Or ummm one of the intake boots? I have no idea...anyone else have this problem?

 

Best thing to do now is find a mechanics stethoscope. Either buy one of find a freind who has one and locate the point of the chirp.

 

"Get's Faster as you rev the Engine" = Rotational noise.

"Sounds like it's coming from the Carbs" ...

Not tied to a "Rolling Bearing" ... audible without being in motion.

Case Bearing
Shaft

There's not too many Bearings or Rotational Parts to blame.
Alternator Bearing
Cam Lobe
Cam Bearing
Scored Valve Bucket

"Chirp" ... Not a Knock?

Insufficient Oiled Cam Bearing
Loose Cam Cap

Cam Chain Tension Causing the Chain to contact a surface other than the guides or bridge.

Remote tracking device installed by the Feds to monitor your whereabouts has become loose and rubbing against something that spins???

 

in lieu of a stethoscope, a piece of hose works fine too. Put on end in your ear, the other on the engine. sugical tubing, clean fuel hosing, etc.

YRMV...

 

Let's hypothetically say it's the alternator bearing...is something easily replaceable or does it take significant engine work to get to it?

Yeah, it's a chirp and not a knock at all. A very loud distinct chirp and very rotational.

 

To get a rotational "Chirp" ... you have to look for something that's Metal on metal.

I would probe the engine while it's running.
I have a fiberglass probe.
4-Feet of fiberglass rod from a Home Depot "Driveway marker"

Cut yourself a probe.
Stick one of those "Blanking Plugs" that blocks-off the Vacuum Sync Port on one end ... sand the other end down to a dull point.

With the engine running ... place the pointed end ON the engine where you need to probe for a strange sound.

Listen to the Rubber-Tipped End.
Actually touch your ear to the rubber tip and listen to the sounds of the engine as its running.

You will be able to Zero-In on the spot that the strange noise is being emitted from ... and, hear the noise as a mechanical sound.

Probing the engine will solve the mystery of exactly where the Chirp is ... possibly -- what it is ... and, then we can figure out what to do about it.

In the mean time ... you should do an Oil Change and examine the Magnet on the Drain Plug.
Replace the Oil with 20/50 Oil and see if the frequency of the Chirp changes with a high viscosity oil lubing the engine.

A "Chirp" ... is usually:
Metal on metal. (Loose Cam Chains chafing Cam covers)
Something that is supposed to be tight ... loose.
Something that is supposed to be lubed under pressure ... Not getting oiled.
A bearing surface too tight.
(A mix-up in assembling bearing caps and one of the caps if too tight around the Journal.)
Aged sealed ball bearings that are scored, pitted or run dry.

I recommend, as a precaution, and to "Rule-out" the Usual Suspect(s) ... you should:

Remove the Valve cover ...
"Test-lift" the Cam Chain off the Center Bridge
Visually inspect each Bucket for its Shim
Examine the arrows on the Cam Bearing Caps
"Sound" ... Tap-upon with a medium-sized drift:
Cam Bearing Caps
Valve Bucket.

For the most part ... sounding machine parts will return a solid noise. Like
tapping a hammer on the flat of a vice.
If anything you sound emits a dull ring ... torque check that assy.

Also ... hand-check the fasteners in the vicinity of the Chirp. That big bolt you see holding two parts together may have suffered a failure and hand-checking will show you it's just sitting there looking pretty and not doing the job.

 

I guess we can rule out tire chirp from bangin' gears! :lol:

 

heh..yeah we can rule that one out. Althought I will say I have a set of Spitfire's on my bike and I am really impressed with how well they grip the corners...makes it really fun to ride!

This morning by chance I started holding my hand down around different areas as I sat on it to see if I could isolate the noise a bit...and the only time it sounded different was around the rear left valve cover area. hmmmm Interesting...I sorta had my sights firmly on the alternator bearing...but it appears it could be somewhere up top in the engine. Will post more as I learn more.

Thanks for your help and suggestions. Rick, I still haven't had time to make that fiberglass tool yet...but I'm thinking it would be handy to have. Is that a solid fiberglass rod?

 

Any kind of rod, dowel or tubing will do the trick. Just an extension to carry the vibes of the engine to your ear without you having to put your ear right on the engine!

I like the fiberglass driveway marker rod. It's a nice addition to your XJ-Toolbox.
The diameter is small. Small enough to ram cleaning patches all the way through the YICS Passage; too.
Won't scratch-up anything.
Great conductor of vibrations.
Non-conductive of electrical current ... so nothing will get shorted out.

Stick a bit of double-sided tape on the end and it's a non-magnetic "Retriever" of small dropped things.
Flexible and strong; too.

 

You can use a long screwdriver, the handle end to your ear, the blade end probe different parts of the engine!

 

Had something similar last year though I described mine as more of a screech which got louder as I rev'd up. I thought it was coming from the left side of the rocker box but it turned out to be one of the boots letting air through.

Faighaigh.

 

Wanted to update you all on my annoying chirp....I've finally gotten it fixed!!! And it cost me less than $100!!! Took it to a buddy's father who enjoys tinkering, he thought it was coming from the engine, but after removing the spark plug from the #1 cylinder the chirp went away...then he traced it back to the manifold between the carbs and the engine. Turns out the O-ring that is built into the boot was corroded to the point that it was allowing air to sneek in causing the chirp. Instead of ordering a new one, he dremel'd out the channel and replaced with a new O-ring...problem fixed!!!

I was so worried it was a bearing or something. Now I have my XJ back...it feels great!!!

 

Congrats! I have a chirping sound on my XJ700X. I wonder if it could be the same problem. Thanks for posting the solution here!

 

mine had this same problem and it was a loose bolt on the carb-to-head boots.
tightened it up and threw some sealer on it just to make sure. worked great.

 

Can just be very hard to isolate the noise to that specific spot. Hope this helps some of you too! Great fix for something that sounds like it could be worse.