What fork oil weight are you running with your Race Tech Spring and Emulator combo?
MrBill
Running 0.70kg springs and emulators with Motul 20W oil - feels good. I think the shim stack needs to be tuned for higher rate springs or you'd need to run oil much too thick.
Understand that the emulator mainly controls damping in the compression side of damping. Installation of the Emulator does not change rebound damping, therefore, adjustment of rebound damping is made by changing the oil viscosity. Racetech says it here:
IF I had to choose, I'd see about matching fluid viscosity according to your fork spring's rate used for your weight. if you're a lightweight rider in 140-170 lbs, I'd use stock viscosity fluid. If you're between 170lbs -200lbs, I'd use 15w fluid. Between 200-230, I'd use 20w viscosity. ANd above 230lbs, I'd look for 25w viscosity(if it exists?).
So, viscosity for compression won't matter b/c you can adjust the amount of flow going through the emulator to match compression w/ rebound.
IF I had to choose, I'd see about matching fluid viscosity according to your fork spring's rate used for your weight. if you're a lightweight rider in 140-170 lbs, I'd use stock viscosity fluid. If you're between 170lbs -200lbs, I'd use 15w fluid. Between 200-230, I'd use 20w viscosity. ANd above 230lbs, I'd look for 25w viscosity(if it exists?).
After reviewing some receipts it appears that due to a misunderstanding on the part of my mechanic my forks left the shop with 5wt oil (it took a while for me to figure this out). Initially they put in 15wt, but the preload spacers had to be recut due to not allowing space for the preload adjusters I had installed and the 5wt oil was inadvertently swapped with the 15wt at this time. I ended up going with the Race Tech recommended 170m of 15wt and things are much better. Problem solved.
It's very interesting to learn that SAE fork fluid weights are not consistent across brands. Some peoples 10w is heavier than others 15w, look for cSt@40* charts to help you tune better. In my forks I had BelRay 15w and I found the rebound a touch slow, I'm replacing it with Spectro 15w which is 13% lighter!
http://www.peterverdone.com/wiki/index.php?title=Suspension_Fluid
http://www.peterverdone.com/wiki/index.php?title=Suspension_Fluid
What's more important to me (vs comparing viscosities on someone's chart) is to just stick with one brand, establish a base line off of that, and then move around with the viscosities within that manufacturer's label. I've stayed with Maxima fork & shock fluid over the years, and this has served me very well with my suspension tuning efforts.
Yes, I agree stick with one brand but just because you read "fill it with 15w" don't expect to get the same results that guy did is my point. For example you said "If you're between 170lbs -200lbs, I'd use 15w fluid. Between 200-230, I'd use 20w viscosity. ANd above 230lbs, I'd look for 25w viscosity(if it exists?)" You didn't specify a brand.
I would say looking at the research that Maxima is very predictable and consistent, I had asked for Maxima 15w when I ordered new oil but the shop somehow heard Spectro. I double checked the chart and decided the Spectro will work for me.
Since I wanted a smaller change than going from Belray 15w (53cSt) to Belray 10w (33cSt) finding another brand in the 45cSt range was easier than buying Belray 10 & 15 and doing the math for blending them. Also much easier to replicate.
I would say looking at the research that Maxima is very predictable and consistent, I had asked for Maxima 15w when I ordered new oil but the shop somehow heard Spectro. I double checked the chart and decided the Spectro will work for me.
Since I wanted a smaller change than going from Belray 15w (53cSt) to Belray 10w (33cSt) finding another brand in the 45cSt range was easier than buying Belray 10 & 15 and doing the math for blending them. Also much easier to replicate.
Mr. Bill,
We need more information than a "racetech" Spring..... What is your Spring Rate?
The Honda CBR 250R came with .45kg/mm springs installed from the factory.
I happened to replace mine with Sonic straight springs at .80kg/mm for my riding weight, style of riding and a regular woman who comes in at 60kilos. I'm using maxxium 5wt oil at 135mm's.
A small but noteworthy advisory: There is no API or SAE rating standards for Fork Oils, so unless you have been using the same manufacturer of Oil, we really have no idea of what viscosity index were running. EX. Motorex 10wt is the same as Amsoil 7.5wt.
Tez gave us good info, but as I don't run Motul in my bikes or customers bikes, I cannot comment on his 20wt. Oil but I do understand that hes replaced his springs with stiffer spring rate.
Pro's statement is inaccurate and quoting something like a race tech brochure is a no no. You can control compression and rebound dampening with viscosity and the amount of oil.
Your "call outs" for viscosity weights to rider weights are also wrong. Sorry. Your statements about Spring rates and the importance of Sags and Squat are accurate. If you really want to educate yourselves....... Read more from fork tuning professionals not Race Tech.
Here's a link and video that everyone here can easily understand.
The correct order of tuning any suspension on a motorcycle is:
1. Select the Correct Spring Rate
2. Set Rear Height
3. Measure minimum oil height and weight in Fork Tubes
4. Ensure Pre-Charge pressure is at minimum for rear shock
5. Inspect for Oil Locks and remove or modify (this is for the people who have swapped out their front ends and may have the device still installed and ensure a min. of 5mm’s remains of travel when fully compressed)
6. Verify and Set to new spring rate and Sag the Machine via Pre-load.
7. Slow Speed Dampening – Oil Viscosity Change, sometimes a needle.
8. High Speed Dampening – Valves, shims or stacking.
9. Oil Height – This changes the last 1/5th to 1/6th of travel in the front forks, raise the oil height in 5mm increments to prevent bottoming or almost bottoming.
10. Shock Pre-Charge – Raise in 1 bar increments or 25 psi (depending on your gauge) to prevent cavitation and match Spring Rate to your performance needs.
11. Fine tune rear ride height for corner exit, and fine tune front fork clamp position for corner entry.
12. Re-Sag the Bike.
Yes, I do this and I wrote this for many other Forums........
If you really want to lose your mind........NOTE: OIL WEIGHTS AND OIL COMPANIES ARE NOT CREATED EQUALL!!!!
WHAT DOES THAT MEAN, Exactly???.......(that was for Mark) !!!
When we’re talking about "low Speed Dampening", you cannot go by the advertised weight on the package!!!! Although some adhere to the SAE, and SUS standards, many do not! For Example, Did you know that a Maxima RF 7wt fork oil is actually lighter than a Spectro 5wt? It's true! Or that a Silkalene Pro RS 7.5 is heavier than a Showa 10 wt?
This is where many tuners get in trouble and start to scratch their heads and other parts of their anatomies! All the while their customers are getting really pissed off and literally throwing money at the problem!!
Here is your Viscosity Calculator!
![Image]()
If anyone has any questions, please feel free to PM or respond to this Post! Woot Woot!
Cheers
We need more information than a "racetech" Spring..... What is your Spring Rate?
The Honda CBR 250R came with .45kg/mm springs installed from the factory.
I happened to replace mine with Sonic straight springs at .80kg/mm for my riding weight, style of riding and a regular woman who comes in at 60kilos. I'm using maxxium 5wt oil at 135mm's.
A small but noteworthy advisory: There is no API or SAE rating standards for Fork Oils, so unless you have been using the same manufacturer of Oil, we really have no idea of what viscosity index were running. EX. Motorex 10wt is the same as Amsoil 7.5wt.
Tez gave us good info, but as I don't run Motul in my bikes or customers bikes, I cannot comment on his 20wt. Oil but I do understand that hes replaced his springs with stiffer spring rate.
Pro's statement is inaccurate and quoting something like a race tech brochure is a no no. You can control compression and rebound dampening with viscosity and the amount of oil.
Your "call outs" for viscosity weights to rider weights are also wrong. Sorry. Your statements about Spring rates and the importance of Sags and Squat are accurate. If you really want to educate yourselves....... Read more from fork tuning professionals not Race Tech.
Here's a link and video that everyone here can easily understand.
The correct order of tuning any suspension on a motorcycle is:
1. Select the Correct Spring Rate
2. Set Rear Height
3. Measure minimum oil height and weight in Fork Tubes
4. Ensure Pre-Charge pressure is at minimum for rear shock
5. Inspect for Oil Locks and remove or modify (this is for the people who have swapped out their front ends and may have the device still installed and ensure a min. of 5mm’s remains of travel when fully compressed)
6. Verify and Set to new spring rate and Sag the Machine via Pre-load.
7. Slow Speed Dampening – Oil Viscosity Change, sometimes a needle.
8. High Speed Dampening – Valves, shims or stacking.
9. Oil Height – This changes the last 1/5th to 1/6th of travel in the front forks, raise the oil height in 5mm increments to prevent bottoming or almost bottoming.
10. Shock Pre-Charge – Raise in 1 bar increments or 25 psi (depending on your gauge) to prevent cavitation and match Spring Rate to your performance needs.
11. Fine tune rear ride height for corner exit, and fine tune front fork clamp position for corner entry.
12. Re-Sag the Bike.
Yes, I do this and I wrote this for many other Forums........
If you really want to lose your mind........NOTE: OIL WEIGHTS AND OIL COMPANIES ARE NOT CREATED EQUALL!!!!
WHAT DOES THAT MEAN, Exactly???.......(that was for Mark) !!!
When we’re talking about "low Speed Dampening", you cannot go by the advertised weight on the package!!!! Although some adhere to the SAE, and SUS standards, many do not! For Example, Did you know that a Maxima RF 7wt fork oil is actually lighter than a Spectro 5wt? It's true! Or that a Silkalene Pro RS 7.5 is heavier than a Showa 10 wt?
This is where many tuners get in trouble and start to scratch their heads and other parts of their anatomies! All the while their customers are getting really pissed off and literally throwing money at the problem!!
Here is your Viscosity Calculator!
If anyone has any questions, please feel free to PM or respond to this Post! Woot Woot!
Cheers
Bradmeister shall we begin the debate that dampening is not the same as damping? lol
You shared some very good info there, I might bring up one point however. When filling the fork with damping fluid (has the correct spring/sag in place) you only need enough oil to cover the damping internals. You can then raise the oil level in 1/4" increments if you need to make the end stroke "ramp up" under braking. The less air spring effect the better as I understand it. For my race bike the fluid level is 35mm below the factory fill level at 160mm vs. 125mm. I'd assume that factory fill levels are an attempt to increase the range of customer weight on the typically stock soft springs and reduce complaints of bottoming/brake dive.
P.S. my favourite fluid screw up is Spectro Golden light (7.5wt) is heavier than many manufacturers 15wt.
You shared some very good info there, I might bring up one point however. When filling the fork with damping fluid (has the correct spring/sag in place) you only need enough oil to cover the damping internals. You can then raise the oil level in 1/4" increments if you need to make the end stroke "ramp up" under braking. The less air spring effect the better as I understand it. For my race bike the fluid level is 35mm below the factory fill level at 160mm vs. 125mm. I'd assume that factory fill levels are an attempt to increase the range of customer weight on the typically stock soft springs and reduce complaints of bottoming/brake dive.
P.S. my favourite fluid screw up is Spectro Golden light (7.5wt) is heavier than many manufacturers 15wt.
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