fork oil

[KeithB]

Could someone confirm this is the correct amount of fork oil to use when doing and drain and refill rather than a complete re-build?
1980 XS650 Special
Thanks!

XSSE-XSSK-int spr and cart damper.....................35mm...169ml oil

 

[5twins]

That is the correct stock amount but these forks work better if you use a bit more. I use about 7 ounces per leg.

 

[L_Kilkenny]

If it was me, I'd collapse the forks down and measure from the top to the existing oil level. Then drain and refill to that point with the new oil. Then you can add or remove oil for adjustments.

LK

 

[650Skull]

If it was me, I'd collapse the forks down and measure from the top to the existing oil level. Then drain and refill to that point with the new oil. Then you can add or remove oil for adjustments.

LK

That is assuming no one has put oil in the forks before, and they could have been wrong

 

[5twins]

And that's assuming none has leaked out, and all the old oil was drained before new was added last time, and ....., and ....., and .....
Well, you get the idea. Best to start fresh with new carefully measured oil amounts before taking any measurements.

Accepted practice is to run the oil about 6" from the tops of the tubes, measured with the springs out, forks compressed. The stock amount (just under 6 ounces) will put the level at a rather low 9" to 9 1/2" down. My 7 ounces is a bit of a compromise and places the level about 7" down. Each additional 1/2 ounce of oil will raise the level about an inch.

 

[L_Kilkenny]

And that's assuming none has leaked out, and all the old oil was drained before new was added last time, and ....., and ....., and .....
Well, you get the idea. Best to start fresh with new carefully measured oil amounts before taking any measurements.

Accepted practice is to run the oil about 6" from the tops of the tubes, measured with the springs out, forks compressed. The stock amount (just under 6 ounces) will put the level at a rather low 9" to 9 1/2" down. My 7 ounces is a bit of a compromise and places the level about 7" down. Each additional 1/2 ounce of oil will raise the level about an inch.

All of what you said is absolutely true. But he knows what his forks feel like now whether or not the level is accurate. So returning to what he is currently running is gonna get him in the ball park. As you also stated, going with stock oil level and weight is seldom the right combo. A rider should really get to know his forks and what can be adjusted for his size and style of riding. IME, forks have to be one of the most ignored parts in a bikes set up and maintenance. I'm guilty of that myself.

LK

 

[KeithB]

Some good ideas. As it stands, the forks seem over damped and going over small bumps drives the handlebars hard into my hands. Too harsh for these old bones.
Changed out the rear shocks and springs and the results were good. Still tweaking.
Looking at the front end now.
Thanks for the input

 

[5twins]

Yes, these forks are have too much damping, both compression and rebound. Modding the damper rods or adding emulators will help.

 

[KeithB]

Modding the damper rods or adding emulators will help.

Do you know if any more detailed info is available?

 

[5twins]

Damper rod tweaks are outlined in the old Minton Mods article .....

http://www.650central.com/tech/mintonmods.htm

Unfortunately, the info he gives about the amount and size of the holes on the damper rods doesn't quite match up to what's really there. It's pretty easy to figure out what needs doing, though (enlarge the 4 holes at the bottom, add a 2nd small hole at the top).

 

[KeithB]

Thanks for the info!

 

[Marlin72xs]

Interesting. I'm only 6.5 years too late, but I remember when I replaced my seals, back in ~78, I put in the prescribed amount of 10-30 and found it to be very harsh. I drained it through the side drain holes, then added the prescribed amount, but with transmission fluid. It feels great and I haven't changed it since.
But, by draining the tubes through the side holes, (went to a construction site next to my house and just pumped it out), did that completely drain the tubes?

 

[5twins]

Probably not, a little was most likely still left in the bottom below the side drain, not to mention the coating on everything. That's why an actual check of the oil level gives the most accurate amount reading. You must be sure you have pumped the forks multiple times to displace all the air bubbles and so the oil has settled as low as possible before measuring.

 

[Marlin72xs]

So I may have had the 7oz, (or close to it), that you suggested. I may try 5-30 or even 5-20 next time. Thanks for the 7oz tip.