So I'm thinking of going up to 15w fork oil with my stock springs. I'm lazy and don't want to take the forks off if I don't really need to. The bike is an 06 with 5k miles on it so I don't think the factory oil is in that of bad shape.

1. Can I just suck some out and put in the same amount of new?
2. Will it hurt anything to mix the weights (10 and 15).

I just want to stiffen them up a little. I'm 210lbs and the stock's are just to soft. So, before I go and get new springs I figured I try heavier oil first. Then, if it still to soft drop new springs in. Still, I don't want to take the front apart if I really don't need to. Am I wrong here?

What is under that little rubber sticker on the side of each fork? Is it a drain hole?

Thanks

You can suck out oil and put new in.
Be sure all weight is off of the front.
Measure your oil level first.
Suck out all you can. Add a cup of new. Bounce up and down gently to mix and suck that out.
Re-fill to same level.

You can change springs that way, too. Hold a rag around it as you pull it out to keep things clean. Normally, spacer would be even with top of fork to an inch above. Screwing in the cap adds about 1.25" of pre-load, which is about the suggested amount.

I changed Suzi's fork springs on the bike. 15 minutes tops.

Heavier oil will slow down the bounce. It will still be soft because of the springs and your weight. Heck, me at 170 and the stock springs were too soft. I'd bottom out. I have 0.85's and 15w. You might need 0.90 and 15w. Sonic has a calculator for the best spring size for your weight and type of bike.

I have to respectfully disagree with adidas, I would drop the fork out and do the oil change with the fork vertical so I get an accurate oil level reading.

heres a nice guide for ya

http://beergarage.com/GSForks.aspx

If you measure the oil when you start and end up with the same oil level, you would be OK.
The important thing would be to measure oil first with the springs in. Since the top of the oil is at an angle, measure at the same point.
I agree that taking them off is best. For ordinary street riding, a 1/4" variation of oil level should make any difference. If you're not able to remove everything (space, time, tools) then it should be OK. Do a proper re-check when possible, like when changing the front tire.

Yea, I know pulling the forks would be best. But like I said I'm lazy. I'm confident I can get the oil level right without doing that. I'm goint to measure it before I suck some out. I'll measure how much I take out. Then I'll put the same back in. I was more worried about mixing.....stock 10w with 15w (might be a tasty cocktail) since I would not be draining the tubes. I can't see how mixing would be bad or damage anything. Because I plan on doing this as a test before new springs I did not want to go through taking the front end apart 2 times.

BTW, I posted earlier I was hearing a clunking sound from the front when hitting small bumps at slow speeds. I still can't find the source of the sound. I was thinking it could be the fork seals sticking. I put a little oil on the sliders and I still have the sound. Gotta be something in the fairing or the springs banging inside the forks. Is there anything else in the forks that could make a clunkity-clunk sound in the forks?

Whats under that rubber sticker thing on the side of each fork? The thingy with the logo on it about 3 inches up from the axle bolt.

I was getting that cluck same as you. Went away when I upgraded the springs to 0.85's and 15w oil.

Oh, the logo is just a logo.

adidas, it has to be the springs or something in there banging. I know it's not bottoming. It does it when I get on the brakes or on the gas.  I guess I find out when I change the springs. If that does not fix it I guess I'll take some yoga classes so I can get my arms up under the fairing because I'm lazy and don't want to take the fairing off either.

Thats my motto......work hard all your life and it will pay of in the end. Being lazy pays of now.

maybe something else. All I know is I would CLUNK when going over the bump to the parking lot at the gym. After changing springs - no more clunk. Maybe it was the OEM springs banging inside the fork - I really don't know. It was a front end fork clunk. I changed the springs without taking the forks off. In fact, I didn't change the oil - just the springs (Lazy - I didn't want to take off the front end.   )