Looking for front fork spring rate advice

[Zer0]

Hey guys.

I'm in the middle of planning out all of my winter maintenance and upgrades.  I'm currently riding a '02 M620 with roughly 12500miles on her.  I spend about 65% of my time commuting mostly highway to work, 25% riding two-up with my wife, and about 10% aggressively riding backroads/twisties.  I'm planning on rebuilding my forks ad replacing the springs while I'm in there. 

So here's my question.  According to the RaceTech website I should be using a .86kg/mm springrate for street riding or a .91kg/mm for aggressive riding.  If I put in the combined weight of my wife and I, i should be using a 1.06kg/mm spring rate.  I know that I'm supposed to round to the nearest spring rate offered.  Obviously I'm not riding two-up enough to justify 1.0kg/mm springs or even a .95kg/mm.  I'm sure that I would be plenty satisfied with .85kg/mm springs while commuting but I'm worried about the rest of the time.  I'm thinking that I should go with the .9kg/mm springs but am questioning the ride quality during my commute.  I'm use to driving race cars and off road trucks.  A stiff suspension doesn't bother me but I don't want to cause a handling issue.  I admit that I am new to playing with suspension on motorcycles.

Will I regret the heavier spring rate?  What weight fork oil should I use with the new springs? (RaceTech says 10W)

Thanks for your help guys.

--Zero

[ducpainter]

My experience is too stiff a spring rate is better than too soft. That said two up riding puts all the additional weight on the rear and shouldn't add to your front requirement.

I'd go with the .85 front, assuming you weigh in the 180 range with gear and bump up your rear spring at the same time to compensate for the additional weight of two up.

Racetech recommendations for rear springs are known to be wrong. Hopefully Speeddog will be by to make a rec.

[Speeddog]

The usual question, how much do you weigh?

[Zer0]

I weigh in at 200lbs without gear.  I had seen in my research that the .85 springs tend to match up with a 180ish lb rider.  That's why I was surprised that RaceTech recomended the .85s and not the .9s.  Again, thanks for the help. 

[Speeddog]

I weigh in at 200lbs without gear.  I had seen in my research that the .85 springs tend to match up with a 180ish lb rider.  That's why I was surprised that RaceTech recomended the .85s and not the .9s.  Again, thanks for the help. 

At 200 lbs no gear, for springs on the stiff side, I'd go with 0.95 fork springs and an 11.6 kg/mm shock spring.
For the OEM 620 shock, a 7" long spring works well.

You're kinda on the line where I might go with 0.90/11.2 setup, depending on the roads where you're at.
And I'd tend to lean that way due to your commuting duty.

With either setup, it's going to be a huge improvement over the OEM stuff.

What are the roads like where you are?

[cmejia1978]

Office Manual says: if spring equal or less 270mm change it... hope this helps, oh yes make sure you have a fork drive tool prior to changing the oil seals, here is the link to the less-expensive one, this one is for non adjustable forks, like the OEM you and me have...

http://www.ebay.com/itm/NEW-MOTION-PRO-RINGER-FORK-SEAL-DRIVER-ANODIZED-ALUMINUM-43-MM-/150990253947?pt=Apparel_Merchandise&hash=item2327b86f7b&vxp=mtr

...and just remember the more you bounce,  the less grip your tires will have... , ( smoother suspension = less bounce )