Those numbers match up with what my Haynes manual states.

Make sure that you have the oil levels balanced (equal) in both legs. I use a large (25cc) syringe (a used one from the local vets!), and some tubing taped to a screwdriver, with the end at 108mm from the base of the handle, so I can then over fill slightly, then stick the screwdriver into the fork leg, and suck the oil back to the correct level (make sure that you have worked the fork legs up and down a few times first, to clear any air bubbles). Make sure you have the springs out first.

Enjoy the markedly improved performance of your suspension with fresh oil in!

 

the 750ss 91 gives 80mm and 457cc. i'd not go that high. but if it has std springs then it might need a fairly high oil level.

 

Yes if the springs are progressive wound they are stock so you need the high oil level unless you are still in grade school weight. the 108mm level sounds right and I believe that is spring out measurement.

If you are going this far and have progressive springs treat yourself to some springs (straight rate) for your weight and then you can lower the oil level and have a better handling/comfortable ride.
Oil weight will be 7.5 IIRc keep in mind the compression valve is restrictive so if you lighten the oil weight to make it softer on compression you give up rebound as well.

 

Am I supposed to measure the level with the spring spacer tubes in the forks, just the springs removed? Or do I measure with the empty forks, then drop in the springs, preload spacers, and spring tubes?

 

in the showa the preload tube goes on top of the spring - spring is first in once oil level is set.

 

fork oil spec...

no spring and no preload spacer tube in fork when measuring oil surface to top of fork tube. 90mm / 3.54inches

page from Ducati workshop manual 94-95-96

Fred

 

the 90mm/390cc is for the marzocchi 40mm.

oil height is a bit arbitrary as in what it effects is the air spring in the last 1/3 or so of the fork travel. with the std crap springs they use it to bring some high progression into the legs, but the rate rise toward the end is massive, you really need heavier springs and lower oil level. there was a bulletin for the early m900 - same 41mm non adj showa as early 750ss and the 94 900cr - that raised the spec to 60mm or so from memory. seems nuts to me.

to set the level, remove the fork caps and retainers to allow the bits to come out. then tip them upside down and everything that falls out needs to be out for the oil level setting. ohlins are the only forks that will specify spring in, and they'll let you know that on the specs sheet. every else i've ever come across is "nothing removable inside" for oil level.

 

Thanks a lot everyone.

I installed racetech valves and new seals, so I'll go to 140mm as per their recommendation, with springs and preload spacers out of the fork.

Speaking of racetech - below is what I found inside the dampers when I took them apart. Was that a stock showa compression valve, or some earlier version of a racetech gold valve maybe?

 

looks like it, but eric will know.

i "test" forks by bouncing on them after i've assembled them - end on floor, hands on top and bounce down. if you want to see how much difference the oil height makes, try assembling them with 90, 140 and 190 oil heights and do a bounce test at each.

 

My memory sucks but I don’t recall anything like that in Marzocchi forks so it would be wise to find out for sure. Also, unless you’re a real lightweight you might want to take advantage of having the forks apart to make some longer spacers and try to get sag in the ballpark. If you use up most of the travel just sitting on the bike the result can only be a harsh ride. Adding some preload with a dual rate spring will have the effect of reducing the amount of travel necessary before the rate rises and that’s nice too.

 

These are showas, just the non adjustable ones. I have them sprung and preloaded appropriately for my weight, I just added (replaced?) the racetech valves while I had them off. If that was already a gold valve setup in there, I do wonder if the new valves will improve the fork as much as I hope.. i suppose the shim stack will be at least a bit different, and I will have the correct oil now

 

Hey, I’d be interested in buying the used racetech gold valves from you if you consider selling. I did the racetech linear rate springs plus new fork oil on non adjustable showas in the fall so the gold valves are next for me. Let me know, cheers


Sent from my iPhone using Tapatalk

 

I may be speaking out of turn here,Lelebebbel, (assuming jimc2 got the bike sorted), but the RaceTech Gold valves have few wear items, imho the springs at this point along with fresh oil are the only significant changes you make,... I've seen 440cc for the stock progressive OEM springs, but I'm a 200lb guy down the road and Race tech recommended the air gap (oil height rather than stating a CC measurement). As others said, that is measured with everything out that falls out once you take off the cap and invert it on the no-external adjustment Showa forks. Haynes manuals are confusing on this point, in my opinion.

Suspension setup is an all night argument,... so many variables. Sportbike editors love to write about adjustability, even worse they attempt to shame the rider that cannot roll on 36 different options for tuning - 72 on electronic suspensions. I'm a 25 year customer of Racetech stuff, and in my experience they can pull out of their database set-it-and-forget it spec's for most bikes with their mods. Slap their stuff in, ride, and if you need to - come up with a coherent explanation of what you want different and they will have a solution.

*Edit - I live in a hot climate, and during the worst of the summer months I often have a passenger stuck on my bike and we ride at higher altitudes where it is cooler. So for me, heat, altitude and weight balance are all major factors before you get into how hard you hammer the front brakes. Generally, I like the heavier weight oil 10 from June to October, but switching out the OEM springs for Racetech was 80%+ of the improvement from the beginning and the valves really locked down the rebound into something manageable from the stock setup.I felt I always had control over the compression on the stock valves, but they too often got stuck compressed once heated up. If I dialed in less rebound the compression went to hell. (Or was it the other way around? What I do remember is that one adjustment from zero obliterated the effect from the other)

I am totally satisfied with my Showa non adjustable forks with RaceTech valves and springs to replace the fancy SS/SP forks one of my bike came with. Change the oil twice a year, crank up the rear shock preload 2-3 turns for a passenger, another turn on the rear shock rebound dampning and go riding.

 

Yes that is a race tech gold valve you are swapping, I assume you installed the newer design. Either design works well if set up properly. I would suspect any differences you feel between the two will be down to the shim stack differences chosen. Simply compare the two and you should have an idea on what to expect.

Although some will depend on how the old valves were set up. Years ago we used to send out our forks to have them valved, after dealing with enough unhappy customers we made the choice to figure some things out ourselves. I can tell you the set up we came up with is NOT a normal race tech setup but it worked for our customers.

What I am saying is that suspension is a system and all the parts work together to create the end product. Think of it like cooking there are many recipes for the same dish and though they both may taste good there will be one the user likes more. Oil weight,shim stacks, oil height and preload are all a recipe and you may have just changed the recipe to a Racetech recipe, enjoy it and continue learning what you like and how to change it.

 

Dialig in

Thanks for all the informative response to the original post.
I set the 7.5wt.fork oil level at 108mm and what little riding I got in before the Winter freezing set in confirmed this is a decent (soft) baseline for the non-adjustable Showas.
I am still unsure if the CR forks are a variation on the Showa GD011 without adjustable damping or
more properly the (41mm) GD031 as used on the 750ss. The only reason I care is that the Ducati service book specifies oil levels of 108mm and 80mm respectively.
Now that there's a few recent miles on it, and the low temps here, the seals are weeping.
Not surprised - this bike sat as bits in a basket since at least 2003.
Gonna do new seals this month, and thus the opportunity to fool with level.
My next question is what the typical static sag and rider sag numbers work for this (stock '94 cr)
on both ends. Suspect there's a spring purchase in my future.....Another slippery slope.
Jim

 

they would be the exact forks as used in the 750ss. the cr is a 750 chassis with a 900 engine.

 

Sorry I was confused as to the original post was not where we ended up ..again. Lol.

If you have the original forks then you want the stock oil height and as for oil weight this is where some will change to a different weight to change damping instead of changing valves. If you are trying to keep the bike 100% stock then the 7.5 is what you want. Setting sag with the stock progressive) springs are mostly a waste of time but you could add 10mm and it should not be possible to make them worse.

Checking sag before you take things apart is always the best idea, most of the times the forks had far too much sag as delivered and if you are going inside it makes little sense to keep the one size (doesn't) fit all springs they came with. Because you are trying to add preload to a progressive/dual rate spring you are putting the soft portion of the spring into coil bind and changing the point you switch to a stiffer rate. 10MM added will be close to the max adjustment of the adjustable forks and since they use the same springs there should be little harm in doing so.

 

Putting the lower rate portion into near coil bind and changing the point switching to the higher rate is a good thing, not a bad thing, by the way. Since even the higher rate portion is probably lower than your optimal rate, you’ll gain a little travel and lose a little nose dive.