xr400 forked 230 after long test

[bajatrailrider]

After many hours testing 230 with xr4 forks with mods and 1990 xr250r shock with mods. V my cr85 forked fox shocked bike. who is the winner sad to say the xr4 forked bike better over the rocks than my cr85 forks. How is it everywhere else  every bit as good as my bike. No surprise as xr4 forks hard to beat. 

[mx4god]

Does the difference in weight make much difference in handling? I know fork weight numbers are on this forum somewhere, but I'm guessing the cr85 forks are a good couple pounds lighter. Just curious, as I like lightweight parts if they function well. Thanks for posting.

[bajatrailrider]

46 minutes ago, mx4god said:

Does the difference in weight make much difference in handling? I know fork weight numbers are on this forum somewhere, but I'm guessing the cr85 forks are a good couple pounds lighter. Just curious, as I like lightweight parts if they function well. Thanks for posting.

The diff in weight zero diff. When I shorten  travel on xr4 fork. I did not shorten enough. So fork little longer bike has more rake.   By accident. Bike works better then mine.   I'm pissed off 

 

 

 

 

 

 

I

[mx4god]

Ha, it seems the improvements are endless... I don't recall seeing a xr400 fork valving thread from you, or at least recently. Did you send them to your suspension guy in Cali, or just do it yourself?

[bajatrailrider]

2 minutes ago, mx4god said:

Ha, it seems the improvements are endless... I don't recall seeing a xr400 fork valving thread from you, or at least recently. Did you send them to your suspension guy in Cali, or just do it yourself?

I did a full write up with pictures.  When    it comes to xrr fork I do all.mods and valving.   

 

[ricky racer]

xr400r forks are 43mm right? I've thought about going to these over my xr600r forks for the rebound adjuster. I think they have them lol.

[PT564]

 xr4 forked bike better over the rocks than my cr85 forks. How is it everywhere else  every bit as good as my bike. No surprise as xr4 forks hard to beat. 

 Like this

 

I think this is a setup issue with the CR85/150R fork. the big hint is "rocks". Those be sharp edged hits.... You should be able to get the CR85 fork to work as well.

What is your valving setup on both forks? And spring rates/ preload. 

[bajatrailrider]

Its no set up issue the best any usd fork wont match rsu fork over rocks and be as plush. not to complain my Cr85 fork great but xr4 cant be beat for plush

[bajatrailrider]

6 hours ago, ricky racer said:

xr400r forks are 43mm right? I've thought about going to these over my xr600r forks for the rebound adjuster. I think they have them lol.

Yes 43mm   they are 11in travel but if you push them down in clamps. you should be able to get them up like your xr6 forks are your late cartridge forks.

[ricky racer]

12 minutes ago, bajatrailrider said:

Yes 43mm   they are 11in travel but if you push them down in clamps. you should be able to get them up like your xr6 forks are your late cartridge forks.

Yes they are 1996  cartridge forks but no rebound adjuster 

[PT564]

I disagree...currently. But I could change my mind.. LOL.

I was trying to get that CR85 fork apart for my project build but the F**&* thing needs a cartridge too holder to get it apart. The darn cartridge kept spinning and wouldn't allow me to pull the nut off that holds the base valve. And I didn't have a tool handy to hold it... UGHH! Pain in the ass. 

So, I know that 43 mm XR400 fork well. I had one.  Jim Lindemann, who use to work for Bob Fox many a moon ago, who started  LE suspension who I'm pretty sure Steve Helbo worked for (after my time dealing with Jim). Jim passed away sometime ago.  I used to go into his shop back in 1989-92 and had him work on some stuff with me there. It was a long time ago.... but, Jim had a good setup for this fork.. I don't have those notes anymore... but from memory you left only  4-5 of the shims in the compression base valve, 6 mm of preload (VERY important - more makes it harsher on sharp stuff), and I believe a 43KG spring. I forget the oil height but I used 7 wt oil as I recall....... Now, Jim did Kurt Wilcox's suspension when Kurt raced the National Hare Scrambles series. Kurt was buddies with Scott Summers and Scott would stay with Kurt sometimes when he was in N. Cal. A few days before a Hollister Hills National Hare Scrambles Kurt and Scott were out riding and Scott tried Kurt's bike. The fork worked better on it..Better then the setup on Scott's race bike.  So Scott actually swapped his fork out for Kurt's that weekend and raced the National on Kurt's fork. That setup is basiclly what's above.

Now, back to these CR85/150 forks. Let me get inside them and see that is there. I suspect they can be made to be plush. It will be a combination of light to no midvalve valving, the right spring rate and preload, and the right oil height. But, hey, I got to get in there and mess with the thing to see what it looks like. )

 

[mx4god]

Yep, I believe Chuck posted some pictures a while back for a cheap CR85 cartridge holder tool using 3/4 square tubing and filing an angle on 2 edges to get it to slide in and hold it. I started taking mine apart and haven't had time to touch them since getting that tool...

I don't know if you searched through this forum already, PT564, but BTR has several threads on all the mods he's done over time to get the CR80/85 forks plush. It involves drilling larger holes in the base valve, removing 7 of 11 shims, as well as removing 2 of 4 shims in the mid-valve (adding a spacer shim in its place). .40kg springs, 2.5wt fork oil and he has adjusted the fork oil level over time. He's done back-to-back tests with other forks and has said it's night and day difference after the mods.

[PT564]

I haven't looked through the other threads on that fork... But I want to get it apart and look at the design and stacks that are in there. I suspect a MV problem that can be resolved. 

That XR400 fork is a open cartridge fork with no MV.  Thus it moves pretty freely without the hydo lock issue on sharp edges.  These MV's cause more problems then they solve for 85% of the folks riding them. Let's face it... 85% of these bikes are not put onto a supercross track where they need that "catch" to prevent hard bottoming off a 90-120 foot triple jump. 

[bajatrailrider]

you are 100% right on mv. also you did not see my post on spacer we use on cr85 mv.  without this spacer no mater what you do on cr85 fork it cannot work well off road use. at the end of the day my cr forks have no more possible mods to make. they work great as any usd fork can. I will not discuss or argue about usd v rsu fork over rocks. as I ride for money and get to ride all types bike  weekly. just my exp after over 50 years riding. the best usd fork I ever road yes ok over rocks. the plush factor over rocks  has not been beat by usd forks as of yet.

[MetricMuscle]

1 hour ago, PT564 said:

I haven't looked through the other threads on that fork... But I want to get it apart and look at the design and stacks that are in there. I suspect a MV problem that can be resolved. 

That XR400 fork is a open cartridge fork with no MV.  Thus it moves pretty freely without the hydo lock issue on sharp edges.  These MV's cause more problems then they solve for 85% of the folks riding them. Let's face it... 85% of these bikes are not put onto a supercross track where they need that "catch" to prevent hard bottoming off a 90-120 foot triple jump. 

I was a wonderin' if you might make it a point to try and determine just how much hole area is needed in a mid valve for the possibility of plushness to be attained.  I'm sure as you are inspecting a new unknown mid valve for the first time you are looking for the typical choke points and/or excessive shims etc.  I'd like to try and establish what the minimum hole area is needed for any valve to flow enough oil that there won't be harshness up to a reasonable suspension speed, like we commonly see on rocks or other sharp edged obstacles. 

I've discussed this some on the size and quantity of holes on the OE damper rods and also the RT Cartridge Emulators.  I am also interested in revalving some Bilstein car shocks but I would like to have a better understanding of the limitations of hole size before tackling that job.

[PT564]

bajadude - let's argue! It will be fun. 

Ok, so I got this POS fork apart. WOW... talk about going back in time. I had no idea this stuff didn't go out of production back in the early 90's.

With that said... Here is something I noticed. This MV is going to be VERY restrictive. So, there are a couple of choices. RaceTech makes one for this.. but I'd like to see it. To see it's design. And, if you did buy one, and one of the Base Valve kits they sell, you're into it like $300 bucks.... add springs, and the cost of the fork.. then you're into it 600-700? Toss in a triple clamp to... $150... $850 bucks for a mini bike fork on a CRF230? Plus brake caliper holder. MY GOD!

Ok, so back to the MV. I'm not sure what you guys are talking about with regard to a spacer... can someone post a pic of this spacer? Link?

What I did see is this collar that the shims float on. That move against the pop off spring in there. See in the picture... I'm pointing at the back of that collar that will bottom out on the shaft once it's "popped" open. Why not cut some of it off?... grind it down till it's flat so it opens further. Has anyone tried this?  This is essencially the same concept that SmartPerformance uses... a pop off valve type of mid valve. Let it open all the way... cut that collar down to let the shims get further from the piston... allow more oil to pass. This is the first simple mod I see. This will certainly help in crease flow for the sharp hits. 

Baja, what do you think? Have you tried this? Note: the collar is not much smaller dia then the ring on the piston. Thus, there is NOT a lot of room for oil to blow past even with this open further. I suspect RaceTech has a smaller diameter compression shim stack to allow for more room between the shims and the cartridge to let oil by inside the cartridge. But, hey, this is a very simple and easy mod. I'll bet you get better compliance over sharp stuff... and port that piston too with a dremel... 

 

 

 

Edited September 20, 2017 by PT564

[PT564]

 

"I was a wonderin' if you might make it a point to try and determine just how much hole area is needed in a mid valve for the possibility of plushness to be attained."

 

I wouldn't bother trying to calculate hole area at this point. What you want to do is increase flow till you get rid of the hydro lock and the fork works the way you want.. you can the back into it and say "ok,,, I opened up this xyz, hole dia is now zxy, cartrige size is now..... then you can come up with a formula so to speak. But let the real world data bring you to that formula first. Then back into the math of it all so you can use it for future reference (but reference only! Never get to hung up on the math... be creative to break now ground and don't worry about all the math of it.  Engineering is great to help explain stuff after the fact, but it's not a great tool at predicting exact results IMO. 

[MetricMuscle]

1 hour ago, PT564 said:

bajadude - let's argue! It will be fun. 

Ok, so I got this POS fork apart. WOW... talk about going back in time. I had no idea this stuff didn't go out of production back in the early 90's.

With that said... Here is something I noticed. This MV is going to be VERY restrictive. So, there are a couple of choices. RaceTech makes one for this.. but I'd like to see it. To see it's design. And, if you did buy one, and one of the Base Valve kits they sell, you're into it like $300 bucks.... add springs, and the cost of the fork.. then you're into it 600-700? Toss in a triple clamp to... $150... $850 bucks for a mini bike fork on a CRF230? Plus brake caliper holder. MY GOD!

Ok, so back to the MV. I'm not sure what you guys are talking about with regard to a spacer... can someone post a pic of this spacer? Link?

What I did see is this collar that the shims float on. That move against the pop off spring in there. See in the picture... I'm pointing at the back of that collar that will bottom out on the shaft once it's "popped" open. Why not cut some of it off?... grind it down till it's flat so it opens further. Has anyone tried this?  This is essencially the same concept that SmartPerformance uses... a pop off valve type of mid valve. Let it open all the way... cut that collar down to let the shims get further from the piston... allow more oil to pass. This is the first simple mod I see. This will certainly help in crease flow for the sharp hits. 

Baja, what do you think? Have you tried this? Note: the collar is not much smaller dia then the ring on the piston. Thus, there is NOT a lot of room for oil to blow past even with this open further. I suspect RaceTech has a smaller diameter compression shim stack to allow for more room between the shims and the cartridge to let oil by inside the cartridge. But, hey, this is a very simple and easy mod. I'll bet you get better compliance over sharp stuff... and port that piston too with a dremel... 

 

 

 

 

I suppose you will figure out the other quirks to the Showa 37mm USD mini fork eventually, I just thought I'd give you a head start.  As far as I have seen here at Thumper Talk, no one running this fork has RactTech mid valves, only base valves.  The base valves are lots more common on eBay and other online vendors, the mid valves are not.  The mid valves not only come with the valve body and shims but also a new "holder", or stem or post which is 6mm OD.  This is because the OE arrangement uses a 7mm stem, valve body and shims, which don't look to be nearly as common as 6mm.  The rest I covered before in another post.

 

On ‎9‎/‎15‎/‎2017 at 6:38 AM, MetricMuscle said:

Are you familiar with the CR85 fork?  It has a few strange features, strange ol'skool mid valve design with oddball 7mm mid valve post.  The base valve is of the same design but I don't recall if it uses 7mm ID shims too.

A BV is available from RaceTech and is readily available from many sources.  They also list a mid valve but it looks to be available thru them only, I haven't found one for sale online anywhere else.

I had considered turning the 7mm post down to the much more common 6mm OD and then installing a RaceTech FRGV S02, a 20mm OD mid valve with 6mm hole in it.

I look forward to seeing what you do to your fork.

 

RT goes into some detail in this:  http://racetech.com/download/InstructPDF/IP FRGV 200602w.pdf

 

[Oil Baron]

3 hours ago, PT564 said:

bajadude - let's argue! It will be fun. 

Ok, so I got this POS fork apart. WOW... talk about going back in time. I had no idea this stuff didn't go out of production back in the early 90's.

With that said... Here is something I noticed. This MV is going to be VERY restrictive. So, there are a couple of choices. RaceTech makes one for this.. but I'd like to see it. To see it's design. And, if you did buy one, and one of the Base Valve kits they sell, you're into it like $300 bucks.... add springs, and the cost of the fork.. then you're into it 600-700? Toss in a triple clamp to... $150... $850 bucks for a mini bike fork on a CRF230? Plus brake caliper holder. MY GOD!

Ok, so back to the MV. I'm not sure what you guys are talking about with regard to a spacer... can someone post a pic of this spacer? Link?

What I did see is this collar that the shims float on. That move against the pop off spring in there. See in the picture... I'm pointing at the back of that collar that will bottom out on the shaft once it's "popped" open. Why not cut some of it off?... grind it down till it's flat so it opens further. Has anyone tried this?  This is essencially the same concept that SmartPerformance uses... a pop off valve type of mid valve. Let it open all the way... cut that collar down to let the shims get further from the piston... allow more oil to pass. This is the first simple mod I see. This will certainly help in crease flow for the sharp hits. 

Baja, what do you think? Have you tried this? Note: the collar is not much smaller dia then the ring on the piston. Thus, there is NOT a lot of room for oil to blow past even with this open further. I suspect RaceTech has a smaller diameter compression shim stack to allow for more room between the shims and the cartridge to let oil by inside the cartridge. But, hey, this is a very simple and easy mod. I'll bet you get better compliance over sharp stuff... and port that piston too with a dremel... 

 

 

 

FYI, PT Cruiser, the 150R internals are different than the CR85 internals.

[PT564]

FYI, PT Cruiser, the 150R internals are different than the CR85 internals.

 

Yep- I'm aware of that... I'm just messing with you btw Baja... You kinda deserve it! )

Thanks for the RT PDF. I didn't see that at all... AND, there is a LOT of information there. Let's discuss that.... 

1. Smaller shaft dia as he wants as much room inside cartridge as possible. Room to move oil past shim stacks between cartridge.  Yes, 7mm is not common... but space is a premium in there... so 1 mm smaller is a lot of oil flow around a stack that is 1 mm smaller then the cartridge. 

2. There is a rebound shim stack on that GV... BUT NO compression one. Which would have been easy to add... common. However, it's a check plate. Why?? To flow as much oil as possible.  Look, the guy has been around the block. He's not stupid. He is a marketeer, but also a engineer and a businessman. He's wearing all those hats. 

3. There is a big reason behind no compression stack. That MV, with the cartridge diameter, on the compression side, is too &%$#@!ING small. Too small to flow oil. So he's got a "by pass" or blow off valve in there. So, do the same thing. Let the balls of that MV breath. Let it blow oil past it for the sharp hits.

And, Baja, have you tried this mod I've suggested? I'll bet it yields gains... let's the collar move further back and more oil flow. Keep just the two shims.... Also, does this "spacer" keep that MV open all the time under the 2 shims you're leaving in there? That would make sense. That combined with the ability for this collar to move further back would lessen that sharp edge harshness. 

NOTE: This RaceTech MV gold kit is the same one they sell for both CR85/150R. So even though the 150R has a different midvalve piston/stack, he's still recc'ding the use of a check valve on the compression side due to the oil flow issue. 

 

Edited September 21, 2017 by PT564