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OEM Fork Spring Mod

Concurious

Guest
Guest
Hi Everyone,

I have been lurking on the forum for a few days now and thought I would join prior to buying a bike (hence the username). I love the idea of getting a Concours (c10) and having something to putz with but not break the bank. I am especially drawn to the idea of modifying the stock springs by cutting them, I previously had a Kawasaki ex500 and that was a very popular mod, and I remember trying to convince some folks on adv rider that they could stiffen the suspension in their dual sport if they tended toward street driving by cutting the springs.

What I am curious about, is whether or not anyone has tried to cut the stock springs, and add a cheap cartridge emulator (The Harley knock offs on ebay for 41mm shocks). It looks like they run about $60, and I was thinking that the emulators in conjunction with cutting about 7in out of the springs (creating a spring rate around 1.0kg/mm for a post 94 spring) and a heavier weight oil, would create a pretty aggressive front end setup on the CHEAP. I apologize if the subject has been brought up before (I couldn't find it), and if anyone sees any issues with my idea please comment. I am going to look at a couple bikes this weekend and I am excited to get my hands dirty. I loved my last Kawasaki, but it was also woefully under sprung at the front end.

Please let me know if anyone is using the knock off emulators and if they would recommend them. I will continue reading, and look forward to getting my hands on a new bike this weekend.

Thanks,
Concurious
 
That's embarrassing, sorry I didn't notice that there is a current thread about the same topic. Thank you for providing the link. I have a bike that I am very excited to look at tomorrow, and hopefully I will be riding it home. Can't wait to dig into it, it seems like there is a lot of potential to make this a very capable bike!
 
Order the Sonic 1.1 or 1.2 spring kit  depending on your weight and riding style. Definitely get the inexpensive emulators but you will have to drill holes in the emulsion tubes  :)  That is a good time to replace seals and  slides
 
Connie Rider, I did get the bike! So far I have been enjoying it as is, and will hold off on mods till winter. I will have to read more, for some reason I thought that Steve in Sunny FL recommended cutting 7in, and that allowed him to have an effective spring rate of something like 1.0 or just shy of it. It would not hurt to start with an inch and then cut progressively more as I test it.

Daytona Mike, I am sure the Sonic Springs would be better, but in this case I am looking for good enough. My motorcycle hobby takes a back seat (financially and priority wise) to projects on my house. Anything that I can do for "free" might actually get done, and I have had some success cutting the springs on a Kawasaki ex500 before so I am happy to try again. The emulators seem like icing on the cake, I am going to try cutting the springs first and if that improves the brake dive I might stop there.
 
Concourier, I'm pretty sure that Steve removed 5".
Calculations showed that as max removal without having spring bind.
I used 4" and was able to set my bike up for 35mm spring sag.

NOTE: When cutting, remove the material from the tightly wound end of the spring.

I also used his suggested settings on the emulator.

NOTE: The Emulator does not effect brake dive as as much as cutting the springs.
          The Emulator is primarily for adjusting the ride. {by adjusting the damping}

Ride safe, Ted

PS; Daytona, knows far more than I on suspension.
      I'm a rookie, and just telling you what I tried.
      Whatever he corrects on my thoughts is best...
 
I cut the springs on my C10 in 2003 after seeing my buddy Art put in Sonic 1.2. His springs were still too soft. Physics class in undergrad taught me the linear spring equation that dictates length of spring is directly inversely proportional to resistance. I have since forgotten the equation as that was 1998 and Physics class is not just remembered in principle. But in practice, if you measure the coil diameter, and divite it into the distance travelled, you will find there is enough room for half the original spring, even after subtracting some of the travel for sag setting. In practice you will find there is virtually no need for sag. I also found that the correct oil for this spring was 80w-90, or perhaps 75w-140. I've forgotten which I used on Mike Dionne's bike. Either way, it was still just a tad too thin of an oil. Important note is that you must use emulators if you do this or else your compression damping would be way too hard. The final result is that the spring is capable of bearing the weight of the bike...something that it can not do stock. Obvious question: Which half the spring do you use, soft or hard? Hard end. That's the loosely would end with greater gaps between the coils.

Minimal necessary tools:
Micrometers
ruler
gray pcv pipe
flat washers with large ID to put between spring and pvc
needle nose pliers to remove cotter pin and preload adjuster
deep socket that fits the spring cap
hex bit sockets
air gun
....
 
"In practice you will find there is virtually no need for sag. I also found that the correct oil for this spring was 80w-90, or perhaps 75w-140. "

Could you explain this recommendation please.
 
Clarification question;
You sed; Obvious question: Which half the spring do you use, soft or hard? Hard end. That's the loosely would end with greater gaps between the coils.

I assume you mean to keep the hard {loosely wound coils} and cut your material and discard it,,, from the soft {tightly wound coils}…  In my case. I removed 4" of the tightly wound coils..

Ride safe, Ted
 
I ran emulators and Sonic 1.1's. ( I weight 245lbs)  . I tested a lot of shock oils and ended up running 50W Spectra shock oil. Anything thinner  and my rebound damping  was too excessive. .
That bike to this day with the ZZR rear shock still  handles fantastic ( in conjunction with  the Meanstreak rear rim.)
 
Douglas: Would you please specify your personal weight. Also did you really not need to compensate for sag or did you pre address this issue by your Gray PVC length in your setup?

As well, curious about your oil weights recommended. That is pretty far afield from Racetech emulator recommendations. Not being critical just curious. I have used 50 weight and now use a mix to 37 weight. Would like to understand your oil recommendation. Once I get this below sorted I may go back to heavier oil experiments.

Currently running emulators less than 1 turn, 4 holes in emulator plate instead of one, oil at 37 weight , stock springs cut to use hard widely spaced coils, and I weigh 285. My sag is not yet up to snuff. Will lengthen pipe inserts next go round to correct.

As aside, I removed my fork brace. Found I could not get it to operate without unduly stiffening fork action in practice. This with it working shimmed and checked unloaded without wheel for binding. Then when completely assembled still no binding. However with bike weighted on road brace affects fork action. This determined by its removal and reassembly several times now. I plan to plastigage it torqued properly one tube at a time. Feel there is an issue as yet not understood in the setup. Suspect it to be in the fork tube stanchions themselves setting up some kind of twist between stanchions and fork brace. That binding fork travel with bike is in use. Yes it is a early model fork that requires shimming. I think fork in action is causing pivoting on shim somehow in use.

Ted, if you are reading this you may remember I was concerned sometime back that brace was altering my suspension experiments unduly. It was. I will repeat my early experiments as time allows then go back to figure and resolve brace issue if possible.

Very curious about these outside box oil recommendations above 50 weight. I am planning to set up a test road course to look into it next season. Got a loop not far from my house where can run one weight then run home and change to another.

Ain't retirement grand! Yeah I know need to ride more tinker less.......Do try to mix both though. Thx all for input!
 
Daytona_Mike, can you clarify something?
NOTE: I am not arguing.  I'm in agreement with you.
          Just confused by your wording.

You sed; I tested a lot of shock oils and ended up running 50W Spectra shock oil. Anything thinner and my rebound damping  was too excessive. .

I think that adding; thinner/lighter weight shock oil would allow the shock to move quicker and you decrease damping??
                            thicker/heavier weight shock oil would allow the shock to move more slowly and you increase damping??

In this article from Race Tech they say that there is a hole in the tube that controls rebound damping, and the only way to adjust rebound is by changing oil viscosity. {See Rebound Damping at fig 3-18 and 3-19}
This Race Tech Article should be read/studied by anyone that is interested in adjusting their shock.
  It has a VERY good explanation of how a shock like this works and what the Emulator does.
  NOTE: It does take some study to begin to grasp.


https://www.racetech.com/page/title/Emulators-How%20They%20Work

Ride safe, Ted
 
I do have another question though.
  I don't recall that a C-10 shock has a hole in that area of the Tube.
      Does anyone know if there is a hole or not?
      If no hole, what acts as the {rebound} orifice in a C-10 shock?

Ride safe, Ted
 
Ted,
To answer part of question. There is no rebound damping orifice at the top of damping rods in the two sets I have (87 and 99, I believe) from air assisted C10 forks. As it would be a very small hole compared to compression damping orifices perhaps it is not needed in this circumstance as parts do not seal that travel of oil enough to warrant drilling that orifice. The damping seal is gapped and may be gapped enough as compensation by design suspecting. There by one less hole to drill for Maw Kaw's subcontractor. Refer to fig. 3.8 and you will see how seal ring gap might be the answer. Just a thought.
Oh regards to you and thanks for posting as always!
 
A second to Ted's recommendation on RT Bible and website. I have personally learned a lot from it on suspension works. Their reference has helped me immensely tuning for brake dive, road conditions in my part of world, and my riding weight. It, for me anyway, took rereading to grasp nuances and overlaps in function. They were very nice on phone with tech as well. That even though I identified as a second hand owner of one of their first emulator sets.
 
Thanks Lee.
What you said makes sense to me, and also makes Mikes heavier viscosity Oil seem the best option.

Ride safe, Ted
 
Of note:

I am checking rebound damping by first applying brakes in curve to compress front end then releasing at normal point in apex. Watching fork rise speed as viewed through fairing down forks. This is dynamic and can be done at different speeds. Anyone know a better way, I am all ears?

I check brake dive and rebound similarly on straight.

Also using a loosely closed zip tie for monitoring full suspension compression. Right now am not getting full 5.5 travel range as I believe am carrying to much oil in forks limiting full compression. Will remove some oil 10ml at time to correct and tune this factor.

Got to get sag set properly before returning to above tests. It is a process. But it has its rewards.
 
I am checking rebound damping by first applying brakes in curve to compress front end then releasing at normal point in apex. Watching fork rise speed as viewed through fairing down forks. This is dynamic and can be done at different speeds. Anyone know a better way, I am all ears?

XXX Check your  rebound damping by compressing the front end and observing how fast it comes back up.
You basically want it to rise almost as fast as you take the weight off the bar, without pogo-ing.
Video's on how to do this are on You Tube.
https://www.youtube.com/results?search_query=basic+motorcycle+suspension+setup+
Here is one with adjustable rebound damping.
  {NOTE: A C-10 does not have an adjuster, and the only way to adjust rebound is with oil viscosity}

https://www.youtube.com/watch?v=sz0z5IgVGSg

I check brake dive and rebound similarly on straight.

XX This may work for fine tuning, but you must first set as the damping as the video indicates.

Also using a loosely closed zip tie for monitoring full suspension compression. Right now am not getting full 5.5 travel range as I believe am carrying to much oil in forks limiting full compression. Will remove some oil 10ml at time to correct and tune this factor.

XXX You do NOT want to use all your travel while riding or under hard braking.
          My guess would be that max is about 80%-90%.
      ie; If you use all of your travel in normal circumstances, there is none remaining for sudden shock loading.

Got to get sag set properly before returning to above tests. It is a process. But it has its rewards.

XXX Did you ever find a cap that allows preload adjustment? This would help sag etc setting a lot.
 
Never found a set of adjustable fork caps when looking last for early C10. Will just cut some new spacers accordingly as I plan to be in there soon anyway.

I am not getting even 80% travel so will have to adjust some. I have too much oil in there compared to stock spec. So have some room to maneuver.

Thanks for tips.
 
Hoping many that are more informed on suspension can chip inhere.
I'm guessing.

Know how to do spring/shock modes but not overly knowledgeable on tuning/damping adjustment.

Ride safe, Ted
 
OK, setting the wayback machine here. I first heard of cutting the springs from Douglas. It works and it's cheap. I don't remember, 5 or 7", I'm thinking 5". I also think I ended up with about the same setup and Daytona Mike, I had racetech emulators, iirc blue springs, 4 holes in the blowoff plate as a form of high speed damping, and oil did end up being about 35W. Working from an old / faulty shoulder supported computer, so YMMV. Steve
 
Thanks Steve. I have "used" early emulators. Do not know about the springs as there is no blue left to/on them. Wish I knew how to compute spring rates. Seems I never have enough talents to ride the face of this earth with aplomb !
 
If the spring is 0.8 kg cutting it in half doubles it and it becomes a 1.6 kg spring. Just get a hacksaw and a grinding wheel and have at it. One of the biggest problems with damping rods is that the velocity of the oil through the orifice must increase to the second power. As a result a bump that pushes the wheel up twice as fast does not give you twice the impact. It's kind of like doubling your speed your impact force at the time of a crash goes up to the second power. That's why a car crash at 70 miles an hour is far more than twice as severe as a crash at 35 miles per hour. The equation for force is F=MA where A equals acceleration and acceleration is velocity per second^2. It's that squared power that's the issue. This is why you're going to need cartridge emulators. The issue is not the thicker oil per se it's the damping rod design. Damping rod forks are inferior to Cartridges. Cartridges have shim stacks the sequentially open so that the compression damping remains consistent. Cartridge emulator is one valve so at least you get some variation and big bumps don't jar you around. Stiffer springs do not make for a harsh ride. Harsh ride comes from compression damping. You need the springs to support the bike. The marshmallows that are in those tubes from the factory cannot support anything. I don't think the bike should be ridden with stock springs. A fully compressed fork is dangerous and does not absorb bumps. Instead of the bike sitting at an inch and a quarter into its stroke it sits 1 inch from the bottom of the stroke. The bike bottoms out over every bump. And when braking fork is completely bottomed out. There is no suspension action when using the front brake when stock springs are installed. no amount of sag adjustment can ever compensate for having too soft of a spring. Fork spring upgrades are mandatory. I achieved a stiffer spring by cutting them in half. Nobody sold a spring stiff enough to support this bike as far as I knew at the time. Achieve good rebound with an oil that allows the bike to bounce up and then settle one time. nobody's goal for rebound should ever be to make it too slow. Too slow is dangerous as it doesn't put pressure on the tire to stay on the road. I personally never found an oil to too thick for these forks. it always seemed to be too fast no matter how thick of an oil I put in. You'll have to watch some videos from that California guy Dave Moss that does the on the throttle show available on YouTube. He has a great explanation. Max McAllister from traxxion dynamics also has a great explanation. Max is the guy that does the suspension for all of us East coast CCS/WERA and AMA racers. The reason why we use him is because when running stock classes we're not allowed to change out fork tubes. even doing so much as changing a brake lever would move me from super stock to unlimited where I stand no chance of winning with an otherwise stock bike. Changing the internals is considered R&R and keeps us in our racing class. And to answer your earlier question I weigh 200 lb. and you won't need to set any preload when putting the top caps on because the springs will be stiff enough.
 
Thanks for answers and more information Douglas. Will check Moss on YouTube and give it all some more thought and experimentation.
 
Thanks everyone, I'm just reading up on this for the first time, after doing a winter rebuild of my 1995 A9.
I got a quote from a specialist suspension firm here in UK, rebuild forks and fit emulators is about £500  :eek:
That's more than I paid for the bike! Way too much for me, plus I'm quite capable of rebuilding them myself, just never used emulators, only rebuilt forks with standard parts and uprated springs.
 
I fitted my emulators myself. Easy enough to do if you know how to rebuild the forks and use a power drill  :)
The scariest part of the emulator conversion is drilling holes in your existing damper rod.
 
If you decide to cut the springs, I suggest maybe 2 or 3 inches at first, then test it. You can cut more off later if you decide it needs to be stiffer, but can't uncut a spring. NOTE: a spacer must be used to make up the difference. If you cut 3 inches from the spring, you should add a 3 inch spacer (many folks use thick wall PVC pipe as spacers). More than about 4-5 inches would concern me (possible coil binding if you cut too much). Instead of cutting the springs, I went with new springs (Race Tech 1.0 fork springs). I weigh 190 and almost never carry anything other than myself. If I did a lot of 2 up riding, I'd go with 1.1 or 1.2 springs. I decided not to do the fork emulators, although I heard they're nice. I used 15w Maxima fork oil. This setup noticeably improved the handling of my bike. Maybe emulators and/or thicker oil would be even better, but I'm perfectly happy with my current setup.

[I didn't realize this was an old thread until after I posted.]
 
Hi again: Quick question for you guys.
I've cut 3" from the tightly coiled end, made 3" spacers, now whats the best order for re-building?  :eek:
Spacer first, then tight coiled end, or any other way? Not sure it makes any difference but its always best to ask!  :beerchug:
 
Spacers go on top and there should be a washer to go the  on bottom of the spacer between the top of the spring and the bottom of the  spacer.  When you cut the springs you want  to remove the soft part of the spring which is the tightly wound part leaving the stiffer part of the spring - the coarsely wound part.. which you did  already state-- so yes.. your good. I assumed cutting 3 inches from the tightly coiled  part would remove all of the soft part of the spring.  How much is left over?  Myself I did the Sonic 1.2 spring kit with Emulators and 50w fork oil.  Your not doing the  Gold Emulators?  I saw cheap clones  on ebay. I am told they work well.




 
Daytona_Mike said:
  Myself I did the Sonic 1.2 spring kit with Emulators and 50w fork oil.  Your not doing the  Gold Emulators?  I saw cheap clones  on ebay. I am told they work well.

Daytona_Mike, how much to you weigh with the above combination? Also how much 50w did you use? Thanks!
 
Lee said:
Daytona_Mike said:
  Myself I did the Sonic 1.2 spring kit with Emulators and 50w fork oil.  Your not doing the  Gold Emulators?  I saw cheap clones  on ebay. I am told they work well.

Daytona_Mike, how much to you weigh with the above combination? Also how much 50w did you use? Thanks!
i weight 235 lbs and I am considered to be an aggressive rider but that is other peoples opinion... not mine.  I tested from 15W  on up AND working with my good friend Douglas (you see his  original post above) . We kept sending videos of  our rebound and we could not get our  bikes to dampen the rebound enough until we both went that thick. We used the recommended amount  of fork oil specified in the
service manual. Please note--you must have Emulators with the extra holes drilled in the emulsion tubes to be able use fork oil that thick.    To this day I still run 1.2's with Gold Emulators (extra holes drilled in the emulators) and 50W fork oil.. The bike handles fantastic. I have the ZZR 1200 shock on the rear. My C10 with this setup handled better than my new  C14. I did not ride my C14 for
over a year- it was not until I installed Ohlins and AK20's on the C14  did I start riding it and stopped riding my C10 although I did take my C10 across the State of Florida and back recently.. My C10 still rocks..love that bike.
 
Thanks for the updates, I've made the spacers from solid HDPE 30mm rod, and ground the cut end of the spring flat, so the 2 parts sit level. I weigh about 175 lbs and am using 20W fork oil.
I was going to add emulators but they are really expensive here in the UK! I can buy the cheap copies from the US for about £86 with import costs added: The same firm also ships them from their Italian base, but the price is double, albeit without the import duty....aka a simple rip-off  :eek:
 
Thanks Daytona Mike! Everyone when posting your fork mods, your weight is critical to others copying your efforts would think. It helps in keeping apples to apples in fork mod comparisons.

I weigh in at 285 on a good day. Well modify my forks slightly from Mikes. Already there save for probably too much oil. I was trying to regulate fork compression on braking. Not stop it, just control it better for my weight. Have too much oil right now would think. Going back to stock oil setting and adding 10cc at time as drawing off oil is too much trouble. Thanks again all!
 
Thanks again everyone  :great:
Just started to rebuild my forks, Should I fit the springs with the tight coils at the bottom? I've also made a pair of steel spacers as recommended, then I'm going with 20W oil at standard level:
 

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I use the bottom as the loosely wound coil weight doesn't have to move before the tightly wound coils react, but I don't think the location really matters on the tightly wound coils. (as they compress first, regardless of location).
 
Assuming that the material you removed was from the tightly wound coil area??

Ride safe, Ted
 
Yes, 3" removed from tightly coiled end. As you say it shouldn't really matter as the spring works exactly the same, either way up...I'll put the loose coiled end in first, then the washer and spacer.
I need to get on with rebuilding my bike now, as I always go for a ride on my birthday, which is the third week in March  :eek:
 
Lee said:
Thanks Daytona Mike! Everyone when posting your fork mods, your weight is critical to others copying your efforts would think. It helps in keeping apples to apples in fork mod comparisons.

I weigh in at 285 on a good day. Well modify my forks slightly from Mikes. Already there save for probably too much oil. I was trying to regulate fork compression on braking. Not stop it, just control it better for my weight. Have too much oil right now would think. Going back to stock oil setting and adding 10cc at time as drawing off oil is too much trouble. Thanks again all!

I have a very rough railroad crossing nearby for my testing.  The Emulators will pop open when I hit those railroad  tracks and I can barely  feel them..  The bike when stock was extremely rough.                  If I wack the front brake lever quick  I can pop the Emulator open ( brake dive)  BUT.. if I squeeze slowly at first  the bike will squat then I  will  brake  real hard and the front will not drop at all (Emulator Valve does not pop open) ...no brake dive.... it took me a while to get it like that... well worth the time.
 
Daytona_Mike said:
Lee said:
it took me a while to get it like that... well worth the time.

Thanks for that tid bit too! These forks are tunable am finding certainly.

Did you drill extra holes in pop off plate? Some came with one or two. Have 4 in mine.
 
Another thing!
When I took the forks apart, the springs, with the preload wound completely back, didn't compress at all, I simply removed the cap and it came off very easily. Normally I've had the cap launch skywards when undone!
Now I'm rebuilding the forks, the springs/spacer/packer slug are above the slider top, and its very difficult getting the caps back in  :eek:
Double checked everything, the length is maybe 3mm longer, is it just that the springs 'relax' and expand back?
They were both on the new length of 543.3mm, no collapse at all but I measured them weeks after removal, is this what you guys found? They must have expanded about 30mm since removal.  :truce:
 
Lee said:
Daytona_Mike said:
Lee said:
it took me a while to get it like that... well worth the time.

Thanks for that tid bit too! These forks are tunable am finding certainly.

Did you drill extra holes in pop off plate? Some came with one or two. Have 4 in mine.
Yes.. 4 in mine as well. That improves low speed damping with the thicker shock oil.
 
jacksdad said:
Another thing!
When I took the forks apart, the springs, with the preload wound completely back, didn't compress at all, I simply removed the cap and it came off very easily. Normally I've had the cap launch skywards when undone!
Now I'm rebuilding the forks, the springs/spacer/packer slug are above the slider top, and its very difficult getting the caps back in  :eek:
Double checked everything, the length is maybe 3mm longer, is it just that the springs 'relax' and expand back?
They were both on the new length of 543.3mm, no collapse at all but I measured them weeks after removal, is this what you guys found? They must have expanded about 30mm since removal.  :truce:

Did you disassemble with the wheel on/suspended?
            reassemble with shocks off bike, or no wheel?
  If so, topping spring was partially compressed during disassembly, and not during assembly.

Also, you are now compressing springs with many tightly wound coils "removed". Will be harder to compress...

Ride safe, Ted
 
Thanks once again Ted! I think everything is going well really, when I removed the fork caps the legs were held in place on the bike, so they were much easier to handle: once I refit them to the bike I'll be able to refit the caps much easier, and of course the springs/spacers are stiffer! Just me stressing too much... :D
 
Daytona_Mike said:
I have a very rough railroad crossing nearby for my testing.  The Emulators will pop open when I hit those railroad  tracks and I can barely  feel them..  The bike when stock was extremely rough.                  If I wack the front brake lever quick  I can pop the Emulator open ( brake dive)  BUT.. if I squeeze slowly at first  the bike will squat then I  will  brake  real hard and the front will not drop at all (Emulator Valve does not pop open) ...no brake dive.... it took me a while to get it like that... well worth the time.

Daytona, what is your turn-in setting on your emulators?
I like what your describing, and may give oil weight a try, but mine are set at 2 turns in {I think}.
  (will check notes)
Assuming I need to set turn-in similar to yours prior to doing oil viscosity.

Ride safe, Ted
 
Lee said:
Thanks Daytona Mike! Everyone when posting your fork mods, your weight is critical to others copying your efforts would think. It helps in keeping apples to apples in fork mod comparisons.

I weigh in at 285 on a good day. Well modify my forks slightly from Mikes. Already there save for probably too much oil. I was trying to regulate fork compression on braking. Not stop it, just control it better for my weight. Have too much oil right now would think. Going back to stock oil setting and adding 10cc at time as drawing off oil is too much trouble. Thanks again all!

\What is your current oil height?

Ride safe, Ted
 
[/quote]

\What is your current oil height?

Ride safe, Ted
[/quote]


37w buy mix of oils now Ted. 

In my last experiments I was increasing oil weights starting from 15w. Went as high as 50w. I had jumped from 30w to 50w skipping 40w. I did not "like" 50w so mixed leftover amounts to make the 37 weight. So for me 40w would have probably been good.

Of note on why I went down from the 50w. The weather was getting colder and felt 50w was very slow to warm up on any ride. Yes it was noticeable. Mixing down to 37w with different leftover oils gave me an acceptable/minimal warm up time on cold days. Yeah it was a subjective observation but noticeable to me.

All oils used where fork oils of same brand save the 50w. It was a branded racing oil with additives "similar" to fork oils.

More than you asked Ted, but perhaps useful to some experimenting with the old C10 fork.

Take care and thanks for all your help in
sorting such out.
 
Have too much oil right now would think. Going back to stock oil setting and adding 10cc at time as drawing off oil is too much trouble.

I asked about oil height. Why do you think you have too much oil?

Ride safe, Ted
 
Ha!

Sorry Ted. Well have to get back to you on that after I look at notes. Guess I need to replace my 15 inch monitor too! Or eyes, or brain..........or all.

Have too much oil over stock spec because I intended it so to experiment with oil volume to control last third of fork travel and brake dive motion. More oil volume less dive. This I read in fork tuning manual. You can tune incrementally. The reason I need to draw off is my fork full travel is restricted. As with all tuning there are compromises and I am too far off.

I have only tried drawn off oil once through dual air valves with a syringe and small brass tube. It was not really workable the way as I was attempting. Best laid plans?! Hence a new plan to refill as stock setting amount and then add oil increments through said dual air valves. My air crossover tube is removed.

I know I am perhaps deeper in to the tuning than some. But have a end result in mind. Will get back to you on oil volume as stands. Sorry for delay and glaring misread!
 
I have a very simple 'tool' to check oil level:
I took a small block of wood, 2" sq and about 1" deep. I had a length of 12mm alloy tube, I drilled a 10mm hole through the centre of the wood, and filed it until the alloy tube was a tight fit. I can now measure the distance of air space required on the tube. Then it's easy to overfill the tube with oil, hold the wood flat on the fork tube, in the centre, draw out the excess oil until just air comes out, done!  :great:
 
connie_rider said:
I asked about oil height. Why do you think you have too much oil?

Ride safe, Ted

Ted still at  a 5.5" oil level and 37w as I was unable to draw off oil incrementally as planned with my apparatus on first try. Fine at that measure for most part but believe it is restricting full compression or I have cut my springs to short and coils are binding. Thinking it is oil amount.  Will pull it apart and re-evaluate in time. Abandoned that part of my experiments till warmer weather.

Working on brake mods now as you know. Then back to fork experiments for the new riding season. Thanks!
 
jacksdad said:
I have a very simple 'tool' to check oil level:
I took a small block of wood, 2" sq and about 1" deep. I had a length of 12mm alloy tube, I drilled a 10mm hole through the centre of the wood, and filed it until the alloy tube was a tight fit. I can now measure the distance of air space required on the tube. Then it's easy to overfill the tube with oil, hold the wood flat on the fork tube, in the centre, draw out the excess oil until just air comes out, done!  :great:

Yes, good one! I was trying to do similar with very small brass tube through dual air caps last riding season. Oil to thick and/or tube to small to get a good draw for what I was intending. Was trying to draw oil without pulling/dissemble of fork caps and springs.

As mentioned will try to add oil incrementally from stock level in same fashion with a syringe this riding season.
 
You can find a Mityvac hand vacuum pump (best in my opinion) at most auto parts stores, I think Harbor Freight, Tractor Supply, and Amazon also has them. You really don't want a mouthful of fork oil. Yuck!
 
I've been using a piece of tubing, and old 1/4" ID seal (sues to set height), a piece of rubber hose, and a Turkey Baster.
Gets the job done..

Lee, I suggest; Go back to an oil level of 6 1/2" from top with forks compressed, and springs out.
Should be relatively EZ to remove air valves and add oil thru those holes if you want to experiment with levels.
Suspect heavier oil and adjust Emulators will do a better job.


Ride safe, Ted
 
That's true...it tastes awful! Pretty bad stuff for us as well. If you use a clear tube its very easy to suck out the small amounts of oil, without drinking any, and this method is next to free of charge.
I have got a vacuum kit, use it for drawing out brake fluid when bleeding brakes, but in the real world, for working on bike forks, its harder to use than a simple length of clear tube.  ;D
 
If you use a vacuum pump, or turkey baster, set level to preferred oil level, stick the tubing in to the fork and suck oil until you get air.
Then move to other fork tube and repeat.  (springs out/forks compressed)


EZ to do and oil height will be perfectly matched in both fork tubes.

Ride safe, Ted
 
1 note on the cheap Turkey baster..
The rubber bulb doesn't seal well to the tube part.
Add a tie wrap and it seals fine.
  {slow, but fine}

Ted
 
connie_rider said:
Lee, I suggest; Go back to an oil level of 6 1/2" from top with forks compressed, and springs out.
Should be relatively EZ to remove air valves and add oil thru those holes if you want to experiment with levels.
Suspect heavier oil and adjust Emulators will do a better job.

That be the plan now. Should have done it that way first. Thanks again.
 
Almost rebuilt the forks now, only mod is 75mm off the tight coiled end of the spring, with a HDPE spacer and steel washer added, on top.
I've added 380ml of 20W oil, its nowhere near the factory level of 171mm, no spring, leg compressed.
The genuine GTR manual says 379ml and 171mm level, leg "extended"...and in the A9 supplement it shows the forks with an air link pipe  :eek:
Should I go with the stated amount of oil, or the level? Not sure, I weigh about 180lb dry weight, any suggestions please!  :great:
 
Do not use liquid volume as it is not as accurate as using oil level.
Set the oil level at 171 mm {Springs out, forks "collapsed"} and be done with it..

Ride safe, Ted
 
Ok thanks, I'll go with oil level: both legs are exactly the same level so I'm sure I measured the correct amount, very strange  ;D
 
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