Pool of oil

I took the left side gearshift cover off of my 750 and am curious about this cavity and hole. I thought it was odd to have a cavity full of oil since the bike has not ran in 2 months so I dried it up with some towels only to find what appears to be a threaded hole at the bottom. Haynes makes note of a "middle gear resevoir" is this what I am looking at?

 

I believe so, it's hard to tell as I've never seen it from that angle.
Common thinking on this is to leave it alone so as not to break it off in the case.

 

That is the dreaded middle gear drain. Like hound said best to leave it alone.

 

That is in fact the middle gear sump drain bolt. They occasionally break off when tampered with and only remove a little less than a cup of oil so most folks don't mess with it.
If you feel so inclined (and have the time to mess with it if the worst happens), you might try to remove it at this point and smear some anti-seize or wrap some teflon tape on that bolt before reassembly for ease of removal later.
Given you have cleaned the cavity out already, I'd leave it be.

 

Thanks guys that explains why it had standing oil in it. I was suprised to see a very small amount of black sludge at the bottom due to the bike only having 10,000 miles but it is 27 years old now.

I have to admit though it is very tempting to take it out and add the teflon tape to prevent any future leak.

 

This is an ongoing (but amicable) disagreement among parties here.
To remove or not to remove. Rick is animatedly against it as a broken bolt there leaves you vulnerable to leaks and it is/can be a huge hassle to remove the offending bolt remains. I'm a by the book fellow (with an occasional fudge here and there) and for the reasons of cleanliness, I feel it is a good idea to remove that oil to avoid the "black stuff" buildup you found. It is not without its risks however so tread gently. If you wish to remove it, a shot of Kroil to soak the bolt would be prudent. That and a gentle heating of the surrounding aluminum should help ease the bolts removal.
That said, I personally have never removed the bolt on my Maxim and when I split its case two years ago, I did not find any buildup in my middle sump so I'm assuming that regular oil changes with quality oil negates this issue. I took the opportunity at that time to remove my bolt, which came out without issue. A smear of anti-seize and it went right back in at factory torque. Just my experience, take it for what you will.
I'm going to assume that ample warning of possible outcomes of this action has been understood and that any effort on the end user's part means that they accept the possible outcomes of this effort. I'm going to let this issue be now. Good luck!

 

:lol: The lawyer in Robert comes out. :lol:

 

OK, speaking entirely from curiousity (550s are chain driven) isn't there SUPPOSED to be oil in there? To lubricate that gear we see in the pic? Or does it just catch oil that is supplied elsewhere to the gears? Last but not least, does Yamaha consider this plug a "maintenance" item, or is it just "there?"

Like I said, just curious.

 

Yup supposed to be oil there for the gear and the manual does say to remove the plug for oil changes. But they also say don't mess with the idle mixture screws

The oil circulates through there but it is a reservoir for the middle gear.

 

+1 Bill ^^^^^

 

Honestly it's probably not worth worrying about because there cant be much more than a couple of ounces of oil in there.

 

About half a cup. It does challenge our sensibilities, to follow the written words or lean on experiences. I'm still leaning on experiences for this one.

 

Yup I don't touch mine. My bike has 42k on it - I had the cover off to replace the shifter seal and sopped out the oil. It was nice and clean.

I figure if it is not causing problems and has broken on others I'm willing to leave it alone.