Gearbox oil goes from fresh gold to black after 15 minutes?

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#1
Fresh gearbox oil goes from gold to grey after 15 minutes?

I have a 1998 yz125. I was working on the clutch and I filled my gearbox up with 10w30 SAE motor oil. After about 15 minutes of riding I pulled the clutch cover off for a general inspection and noticed that the oil was already black/grey colored.

Is that normal?

Also, is it safe to spray carb cleaner inside the gear box (while the cover is off) in an effort to clean any sludge that might be inside? Or, will carb cleaner hurt the clutch discs or inner seals in some way?

TIA,
Ryan
 
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Backslayer

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#2
Grey oil, can mean a couple things, most likely its just clutch material, I would put the oil in a clear jar and let it sit, if water is on top then its your pump, run a magnet in the oil and see if you pull any debree out, if nothing its clutch material, not a big worry, as far as the carb cleaner I wouldn't it can dry out your seals.
 

CaptainObvious

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#3
DO NOT SPRAY CARB CLEANER IN THE GEARBOX.

You don't mention if this is a new clutch or not. If this is a new clutch it is normal to see a large amount of particles after such a short period of time. This is due to the plates becoming "friendly" with each other. If it doesn't stop, you may have an assembly problem.

If this is an old clutch, it may be time to replace the friction and pressure plates.
 
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#4
The clutch has a total of about 5 hours on it or so. I replaced it a few weeks ago. Would that be considered new? The clutch discs and plates looked ordinary (no missing clutch material, chunks of metal, etc).

Ryan
 

Backslayer

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#5
you can't tell if any material is gone without a mic, and you shouldn't have nothing to worry about, mine is grey everytime cause its a 125 and I use the clutch hard
 

CaptainObvious

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#6
Is the fluid gray or black?
 
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#7
It is definitely grey. I'm used to thinking about motor oil. I will edit the title.

Backslayer: I was referring to a missing chunk of disc material, not a thousandth or two ;).
 

CaptainObvious

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#8
If it's grey, it's normal.
 
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#10
Aluminum drive plates? My feeling is gray is normal under those circumstances, but steel drive plates do not contaminate oil like alum ones do. Our bikes do not turn oil gray that quickly, and we are heavy clutch users (thanks to "hit you with a stick Gary Bailey"). :whoa:
 
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#11
2-Strokes 4-ever said:
Aluminum drive plates? My feeling is gray is normal under those circumstances, but steel drive plates do not contaminate oil like alum ones do. Our bikes do not turn oil gray that quickly, and we are heavy clutch users (thanks to "hit you with a stick Gary Bailey"). :whoa:
Yep,aluminum,yuck! Never noticed a performance loss going to steels. Never had issues with notches on the hub.