Your 02 RK came stock with 10 weight in the forks , and 7 weight in the rear shocks to begin with.
HD fluids
E - 5wt
B - 10wt
SE heavy - 15wt
SE race - 20wt
So using HD fluid, if B in the forks, then would do a 50/50 mix of B and E to come with 7'ish fork weight in the shocks.
If using SEH for the forks, then would do a 50/50 mix of B/SEH to come up with 12'ish for the shocks.




Also remember, your dealing with two different things in regards to fork/shock oil. The weight itself will determine the speed of the dampening that the shock/fork moves for travel and the final total amount will determine the stiffness of bottom of stroke travel. More fluid (within reason and not too much to just blow the shocks/forks up), means less air volume, and air pressure will pump up faster at the bottom of stroke. Hence, progressive springs change the bottom of compression to increase the spring tension there, so add this into the math of final oil amounts to reduce the total amounts in the end (so the front to back is still balanced if you are only running progessive springs on one end of the bike).

 

Interesting, my '02 service manual calls for type E in the front? So on your basis above that's a 5wt, so perhaps the reason my front end feels a littl "pogo"; the thin oil making the dampin react so quickly?

 

I took the stock air shocks off of my 14 ultra limited because the right side was leaking oil and I replaced them with the 13 inch Harley-Davidson premium hand adjustable shocks from a 2018 ultra limited and I couldn't be happier. Smoother better ride overall.

 

Yes, the thinner the oil, the faster is can flow through the ports.

 

Just to add here, on the 12" air shocks, HD (showa) uses 11oz of oil in each.

So on the front forks, your going to use the normal amount of fluid, then as you are changing out the oil in the shocks with the correct weight oil for the weight you used in the front shocks (15 in forks, 12 in shocks is a good mix), start with the 11oz of fluid to start with.
Note, shorter shocks will have slightly less oil in them as a starting point, so messure what you are pulling out of each shock of fluid, to use as your starting base line of the fluid to put back in.

If the rear end seems to squat more than the front end as your going down the road going/over bumps/around corners on bottom of stroke, the pull the air from the back shocks line, push the air line and coupling piece in all the way to remove the air line from the shock, and Home depot has you covered on a syringe that you can use to add another .5oz of fluid into the shock with them still mounted on the bike. Again, to less oil, the more that the shocks will want to bottom out, while the more oil you run in the shocks (do not exceed 12oz), the firmer that the shocks will be on the bottom end of stroke. So since it easy to add more fluid this way, only add 1/4oz at a time, until you have the front and back end handling correctly with each other.



Hence the quick way I can tell if the rear shock amount of fluid is correct, it's to get the bike into a sweeper are speed, and see if the front and rear end seem to be connected/working together, or if the back end is going wild with it compressing too much over the front end in the sweeper instead (feel like you are riding a chopper through the corner with the back end squatting down too much isntead).

And just a note, and if you add too much fluid to get the shocks too stiff at bottom of stroke with too much fluid), you have to pull the shocks off the bike to turn the shocks over to drain that amount out. Also, if your going to be ridding two up most of the time, then dial the amount of shock fluid in for that two up riding. Again, the amount of air that you use in the shocks, is to set ride height/sag alone. If you look in your carb/TB side bag or manual, it will give you the amount of air to add to the front or back, for every 25lbs extra weight over the base line of 150lbs that the springs are set up for with no air added to the system. On mine, is only 1lb of air per 25lbs over the 150lb base line rider weight, but on other bikes is more air per extra 25lbs isntead.

So again, I run 15weight in the forks to oem fill amounts, 12weight in the shocks to 12oz, but bike is set up for two up. If your setting up a bike for one up, then drop the shock fluid down to say 11.25oz to start (for 12" shocks), and you can add a little more fluid at a time if needed to each shock, to get the front and rear ends working together correctly on compression in the end. If your looking for say a softer ride, then stick with the 10W in the forks, 7 weight in the shocks, but do take the time to work with shock fluid amounts, to get the front and back end dialed in together. I can tell you that the 11oz oem is slightly too little to start with (on the 12" shocks), but since it easy to add more fluid as needed, may want to start there on the initial shock re-fluiding to begin with, then add in 1/4oz a a time with test rides, to get the forks and back shocks working together correctly in the end.

 

Ohlins

 

Super detailed post dude, thanks! Next thing on my list once I’ve finished my belt replacement!

 

Get a set of Legend Revos, great ride quality and no need for a shock pump. Keep your OE ones just in case you have to send the Legends in for repair (they have a lifetime warranty) that way you have something to put under the bike.

 

Hey Dano, I just finished rebuilding my front forks (did bushings too) and filled them with 10wt Motul Factory Line...

Going to source some 7wt for the rear and change the fluid out too - will start with the 11oz and work from there; I might get away with 11oz as I am only 74kg (which is about 160lbs in your money)...

Thanks again for the super detailed thread!

 

previous owner might have changed to a heavy oil, too heavy for your riding weight. stock oil is too thin (5w?), 10w works for a light-to-medium rider, 15w works best for fat asses and 2-up / loaded.
never tried 20w, my guess is that would be too much dampening.