[Shutterbug]

Today I changed my engine oil and differential oil , and I think I may have overfilled the differential. Is this harmful? By the way, I added synthetic oil to the diff.

 

[Retro Rich]

Did you fill it through the "check plug" on the side of the differential? If you did with it sitting on the sidestand, any extra/overfill would/should have come right back out at you. Just pull the check plug on the side, if there's only a "dribble" coming out when you pull the plug and it's not pouring out you should be fine.

Synthetic=good; nothing wrong there.

 

[Shutterbug]

Retro,
I was holding the bike vertically off the stand and had the wife fill it. When I did it on the side stand, it seemed like more oil came out than went in. Should I drain the excess, or just leave it alone?

 

[syhman]

drain it
...it should be flush with the lower edge of the oil filler hole

 

[Retro Rich]

Yep, what shyman said. Pull the filler/check plug on the side, with it on the sidestand. It's designed to check while the bike is on the sidestand, and should be level with the bottom of this hole. If you've got too much, it will run back out and get itself at the bottom of the filler hole. If you're filling from the filler hole and more is coming out than you're putting in, you're just getting it in too fast or hitting something to obstruct it while you're filling. Just take your time and be patient. You can use a small section of hose attached to your bottle to get it to "fill" back in farther in the differential and get a better angle as well.

 

[Green Ghost]

Yep

Get it out of there, If it's to full it could suck the top right out of the piston. Better too low than too high, GG