02 F4i Fork Oil Weight w/ .95 Race Tech Springs

Ok here is the situation:

I have stock fork springs and stock oil which is 10w in my 02 F4i Track Bike

I picked up a set of .95 Race Tech Springs

To my understanding I can leave the stock valving and everything else but I should put heavier oil back in.

What weight oil should I put in and what brand?

Thank you for your time and help.

 

? Stock is something like 7 weight on the F4. You don't want heavy oil in cartridge forks, certainly not heavier than 10 weight. They will be stiff on cold days.

 

I am in the exact same boat. Gonna drop in a pair of .95's and I heard you can go with a little bit heavier oil to help dampen the spring. Stock weight is 10 so would you guys recommend stepping up to a 15W? I know that a revalve would be ideal but I'm only a casual trackday guy right now.

 

15W is too heavy.

 

I have .90 Racetech springs, Ohlins valves and Ohlins R/T oil on all my bikes, they feel great on track, on street they are too soft for it but I only go street riding onece in a while

 

Wait. Something you have valved for the track feels too soft on the street?

 

Maybe am no phasing it right, at the track is a perfect set up, but when I get to ride a bit on street the spring strocke seems to be to short or soft and when I hit a big bump I feel bottoming out the forks.....

At the Racetech site, they ask
Racetrack= softer
Street= next setting stiffer base on your weight, so I choose track b/c I am more there(when possible )

 

Stock is 10w. The stock compression valving will be way too much and the rebound won't be close to enough[remember stock is only .68kg/mm]. I have racetech .85kg/mm springs [street bike too] in my 06 f4i with gold rebound valves. Racetech said to use 5w but I had the suspension guy shim the rebound valves for the 10w. Rebound is set about middle of adjustment but the compression is only 1 1/8 out from full soft, anything more on the street and you're loosing tire contact from bumps.

 

I was looking at the oil viscosity chart and the Maxima 15w is only a little heavier than the Honda/Showa ss8 (10W), which sits pretty high on the chart for a 10w.

With the compression turned all the way out, do you think it's still going to be too much?

Here's the wiki link to the chart -
http://www.pvdwiki.com/index.php?title=Suspension_Fluid

 

You don't want your compression valving turned all the way out.

 

You can't solve valving problems with oil viscosity. The adjusters will only affect low velocity movements. With the stiffer springs and heavier oil, it's likely the front will be overly stiff, especially on high-velocity bumps.

In other words, if you go with a heavier oil to compensate for inadequate rebound valving, and you'll end up with way too much high-speed compression damping. At best, you'll end up ruining tires and at worst, you'll end up with a bike that will have poor front-end feel and may have poor traction.

What kind of problem are you trying to solve?

Spend the money and have a good tuner revalve the front for the heavier springs and your riding habits, or at very least, make one change at a time. Ie: do springs change and fresh oil w/ stock oil height and then test (carefully). Keep in mind that having faster rebound response is not automatically a bad thing.

Take a moment to read this page. Keep in mind that it's generally talking about dirt bike suspension, but the same logic applies to street suspension.



http://www.shimrestackor.com/Code/Sample_Applications/Spring_Change/spring-change.htm

 

I use 125/150 weight cartridge fork oil. Spectro or Maxima brand, although I prefer the Spectro as it is synthetic.

You do not want to go with an oil that is too thin or you lose the low speed adjustment range.

Too thick is too thick, that should not need any explanation.

 

I read through that and now I'm more confused. =(

I am just a novice and wanted to properly setup the bike for my weight and sag and I thought buying the spring would be enough. Then I read about how there won't be enough rebound dampening for the spring. Then I read about using heavier oil to help get more rebound. Then I read about how you should not use oil weight to change dampening. Then I read that I should get another rebound valve. Now I'm reading that I need to modify the shim stack?

AGGHHHHH

All I want is a cheap and effective upgrade to my stock suspension so it can be properly setup for my weight...The only slight problem I was noticing was a bit of brake dive and pushing to the outside on corner exit.

How does this sound - remove one shim from compression side over to rebound side - Use a racetech rebound valve, 7w oil?

 

Looks like some people are saying it's best to tune damping through the shim stack and some say with valving. Looks like just a racetech rebound valve would do the trick but supposedly the shim stack is kind of conservative. I have no idea about this stuff but I'm definitely willing to give it a shot if I even knew where to start with the shims.

 

Okay this is my last go at this. If these don't sound like decent solutions for a slow guy (high speed damping probably won't be as important) then I will just go with race techs recommendations. Keep in mind I want to go with the cheapest solution to get an adequate setup.

1 - Same oil weight = Not enough rebound, too much compression with new spring. Fix = Add shim to rebound low speed shim stack, remove shim from low speed compression side = should affect overall damping (high/low) and just add/remove shims until it feels pretty good with adjustments in the middle range.

2 - Slightly higher oil weight = A little better on the rebound, way too much compression, especially high-speed. Fix = Remove low and high speed shims from compression side and maybe add one on low speed rebound side, remove one from high speed rebound side.

3 - Lower oil weight = Compression good, Rebound way off. Fix = New rebound valve and/or bigger increase on shim stack.

 

Based on your posts you have no idea what you are talking about. I am not trying to be a prick, it is what it is.

The best thing you could do is save up your money and have someone that does suspension work upgrade your forks.

You could also buy Race Tech's new suspension book. There is a lot of good info in it.

 

That.

 

Just to be clear, my recommendation is to have a suspension guy do the forks AND buy the book. Not or buy the book and try it yourself.

 

Buying the book right now.

Agree - I absolutely don't know what I'm doing ...Gotta start somewhere. This is where I have been led, but sending off my forks for $1000 of work and a month of downtime... Fuck that. All I want is the sag setup properly with the right spring weight and the simplest solution to get the damping good enough for a noob.

I don't have a ton of money and I can't send my forks away since this is my transportation as well. Ebay forks = more money.

Is it really such a bad idea to drop in a gold valve rebound kit from race tech along with whatever oil they recommend (which from what I have heard from others will be a lighter oil) or is that not good enough for the race gods of this forum who require top notch ohlins parts?

If I had a dedicated track/race bike that sat around, or a disposable income, or if I did this for a living, then sending off my forks for the mad work sounds like a tits idea and all, but unfortunately this is not the case for us all.

 

I looked back through the thread. Aside from one post where someone commented that they had Ohlins parts in their forks, no one recommended that you put Ohlins parts in your forks. In fact, as far as 20mm kits go, IMO, there are a lot better options out there than the Ohlins parts. So if I was going to recommend a kit, it wouldn't be that one.

And if you had actually consulted someone that does suspension work for a living, you would find that your $1000 estimate is way off. In fact, for what you're asking for, a shop like mine would take care of you for about $300. And turnaround time is usually about a week, if not less. You need your forks opened up and then they need to be cleaned, have the seals changed, the right springs put in, the valving touched by someone that knows what they are doing, and the right fluid put in and set at the right level. The only new parts going in will be the spring (and spacer) and some shims. Pretty cost effective way to get your forks right.

If you consider what a rebound valve kit would cost you (and then consider that you have no idea what you're doing and would most likely have your forks apart for longer than a professional would) and then base everything you do once you're inside the forks off of bits and pieces of posts on different internet forums from people who may or may not know what they are talking about, I'm not seeing the savings.

Good luck.