Mechanical Grinding Noise

[Conrad]

Hey guys,

I recently replaced my stator in the hopes that it would solve my electrical issues, and thankfully it did!  Unfortunately on my first ride right after this, I noticed a mechanical grinding noise coming from the bottom front of the bike.  It only seemed to happen at lower RPMs, but that could just be that I couldn't hear it over the engine as it got louder.  I've looked around on the forum and from what I've seen, the starter clutch is a likely culprit? If anyone can help me confirm this I would really appreciate it.  I'd rather not start pulling things apart or ordering parts before I'm more certain about what's going on.  Also, I noticed most of the links people provided that had information about starter clutches are all dead/the websites are down.  If anyone has that info saved I would love to see it! 

Thanks!

[fret not]

Well, the simplest way to know for sure is to remove the stator cover and remove the rotor, as the starter clutch is attached to the rotor (flywheel).  There is a recent discussion of this that pretty well covers most of what you need to know.  You will need a puller and a big hammer.  Oh, the title is something like "flywheel removal, now what"

[QBS]

Does the grinding noise change with engine rpm when in neutral?  Does it change with bike speed, regardless of engine rpm?

[jefferson]

Since this noise started right after installing a new stator it is more than likely associated with what was done. It's not always 100%, but a very good possibility. Pull the cover back off and see what you can. The flywheel is magnetic and something could have attached itself to it without you seeing it.

[QBS]

If your engine is the source of the noise you will certainly need to change your oil and definitely the filter before the engine is operated again.  Closely inspect what the filter has collected.  Shiney things there are always a bad sign.    It probably would be a good idea to somehow flush out the engine, it it could be safely done.

[Conrad]

Yeah, I guess I'll start taking it apart this week if the weather stays nice enough.  I didn't notice any change in noise level when in neutral or if I increased the RPM.  Not sure how relevant this might be, but my bike only has ~5,500 miles on it.  However, last summer when my stator was going out I was spending a lot of time cranking the engine, so maybe that could have something to do with it?  Anyway, thanks for the input everyone!  I'll update when I make some progress on the taking-apart bit. 

[QBS]

If you rode the bike without the engine running, would you still hear the noise?  I'm trying to isolate the "grinding" to either the chassis or the engine.

[Rikugun]

Since this noise started right after installing a new stator it is more than likely associated with what was done. It's not always 100%, but a very good possibility. Pull the cover back off and see what you can. The flywheel is magnetic and something could have attached itself to it without you seeing it.

What he said. Maybe it's as simple as the wire guide is rubbing the rotor.

[dingleberry]

I'm wondering if the grinding noise is a consistent pitch or maybe erratic like a concrete mixer as if something is rolling around in there.

[Conrad]

Just finished up finals so I am finally able to figure out the problem.  Started it up and the sound began immediately.  Also started to smell somewhat like electronics burning, so I shut it off.  The sound was consistent and didn't happen if the engine wasn't running.  I just emptied out my oil and I saw some metal flakes :/  I'll start pulling things apart when its done draining in a bit.

[Manmelvin]

I'm wondering if the grinding noise is a consistent pitch or maybe erratic like a concrete mixer as if something is rolling around in there.

When Conrad and I started the bike and heard the noise it sounded much more like a really bad rotational whirring/whining noise than erratic clunking as if something was loose in the crankcase.

[fret not]

We are becoming ever more curious, has the case been removed yet?  What did you find?

Was anything else taken apart when the stator was installed, or was just the case and stator all that was done?

[Manmelvin]

We opened the crankcase and nothing looked abnormal. The oil had some metal shavings in it :( but otherwise nothing out of the ordinary visually. In a few weeks we will be able to take a look at it again and use a puller to remove the permanent magnet flywheel to take a look at the starter clutch. We will probably also check the starter motor since that was about the area the noise was coming from.

[jefferson]

I kind of doubt that the starter motor is the cause of the metal particles in the oil or the sound for that matter. The only way I see metal getting in the oil from the starter would be the gear on the end of the starter. Most likely suspect would be your starter clutch.

[fret not]

What color of metal shavings?  Attracted by a magnet or not?

[Bill]

Are you absolutely sure the sound is not coming from the speedometer cable?  The whirring/erratic nature of the sound was something I have experienced on my Z.  Uncouple cable at the front wheel to check.

[QBS]

Bill, what is the status of your speedo noise situation?

[Bill]

I replaced the speedo/tach cluster and speedo cable with units I bought on ebay. I think whirring was coming from the speedometer itself.  At least for now I'm back to quiet operation.

[QBS]

In all likelyhood the noise you complained about was caused by the speedo head cable input bushing being dry.  Very common in older Japanese speedometers.  Very easy and cheap to repair.  The bushing accepts the speedo cable and does not open into the speedometer interior.  To lube the bushing bearing, remove the cable from the speedo and attempt to force grease into the speedo interior via the bushing cable receptor hole.  Use your finger to very aggressively attempt to push/work grease into the inside of the speedo head.  The more aggressively the better.  However, since the cable receptor hole is closed ended you will fail to get any grease into the interior of the speedo unit.....BUT.......you will end up forcing the grease into the tight space between the cable receptor bushing and  the speedo head casing that it spins within.  That is where the source of the problem resides.  The small amount of grease applied there by the manufacturer drys up and disappears leaving a dry bushing bearing that, if left unserviced, will eventually destroy the speed head.

Your replacement unit should be serviced as described above as soon as possible.  Speedo units maintained in this way will provide decades of trouble free operation.  Quite possibly your original unit would respond very positively to this servicing and be brought back to excellent health..  Experiment on it and see what transpires.  FYI: I have owned and maintained my '83 V since '84.  Current mileage estimated at 88K.

[Conrad]

Are you absolutely sure the sound is not coming from the speedometer cable?  The whirring/erratic nature of the sound was something I have experienced on my Z.  Uncouple cable at the front wheel to check.

Unless it somehow moves while the bike is on the service stand, I'm pretty certain its not the cable.  We have it open right now and are working on getting the flywheel off.

EDIT: Bent the bolts on the puller, will get back to it tomorrow.