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Thread: inverted fork help

  1. #1
    Join Date
    Feb 2010
    Location
    oregon
    --
    33

    inverted fork help

    i have seen quite a few 250R's with inverted forks, but i dont understand how to mount them?

    do they fit in stock triple clamps? i wouldnt think so.

    what forks work the best?

    and how much revalveing does it take for them to work right?

    do you have to have triple clamps made for them?

    what axle/brake setup work on them?

    i would love to put some on my bike so if anyone has done the swap some advice would help out a bunch.

  2. #2
    Join Date
    Sep 2008
    Location
    Northwest Indiana
    --
    550
    Any questions: Contact Jason Hall on the site, he is doing my invert set up for my 1985 Tecate right now! I can tell you this, it takes some custom fabricating when it comes to getting this right, and he is the man that can do it! Custom trees will have to be made!

    I used 2006 YZ85 forks for mine. I wanted to use the KTM85SX forks, but I couldnt find any available!
    1985 KXT250 A.K.A. "Doom"/Multiple Engine Combinations/Jason Hall Inverts/HRE Swing Arm, Cal Fab Swing Arm/Jemco Pipe/Buzz Saw Cylinder, Klemm Research Cyinder/PWK Carb/PVL Ignition/Dura Blue Axle/Mosh Custom Seat

  3. #3
    Join Date
    Feb 2010
    Location
    oregon
    --
    33
    sweet! thanx man. really just 85 forks? i would figure at least 250 forks..but i have no idea thats why im asking.

  4. #4
    Join Date
    Oct 2004
    Location
    Maryland
    --
    3,077
    Larger forks do work but the smaller ones from the mini dirt bikes are a bit more proportional and take less work to get installed. HOWEVER both the full sized ones and the smaller ones have trade offs and their own unique issues. Specifically the KTM forks are known even by the dirtbike people to need seals constantly. I've been doing about a set of seals a year on my KTM forks.
    And that's the rest of the story. ~ Paul Harvey

    "Yes its broken, but does that really surprise you?."
    "What happened? What does it look like happened?!?!"

  5. #5
    Join Date
    Oct 2004
    Location
    Ontario, CANADA
    --
    4,538
    I have shortened Cr125 forks on mine, with jason hall tripples and front hub setup.
    He is for sure the man you need to talk to!
    RPFLU member and co-owner.
    Hardtails is all we do.
    #NOLINK
    #MAKEHARDTAILSGREATAGAIN
    #SUSPENDTHIS

  6. #6
    Join Date
    Feb 2010
    Location
    oregon
    --
    33
    i see. why dont the larger forks work? just to bulky? i just put seals in my stock forks tonite and saw that one is bent so im going to replace it soon.

    some of the guys at local shops i have been talking to said that inverted forks dont really help to much and look cool more than anything. is that compelty true?

  7. #7
    Join Date
    Oct 2004
    Location
    Maryland
    --
    3,077
    Quote Originally Posted by chuk85 View Post
    i see. why dont the larger forks work? just to bulky? i just put seals in my stock forks tonite and saw that one is bent so im going to replace it soon.

    some of the guys at local shops i have been talking to said that inverted forks dont really help to much and look cool more than anything. is that compelty true?
    The larger forks work fine, they just require more work to make triple clamps for.

    As far as your guys at local shops, they probably think you're wasting your time with you three wheeler and are indirectly discouraging you against inverts.

    As far as are they "worth it". Inverts vs. Standard forks are night and day different. Standard forks are like pogo sticks, inverts are like bouncing on a cloud.
    And that's the rest of the story. ~ Paul Harvey

    "Yes its broken, but does that really surprise you?."
    "What happened? What does it look like happened?!?!"

  8. #8
    Join Date
    Feb 2010
    Location
    oregon
    --
    33
    ok so i need to find some cr 85 forks?? or yz maybe? ktm?

    what do you do for an axle? and brakes?

  9. #9
    Join Date
    Sep 2008
    Location
    Northwest Indiana
    --
    550
    I used the yz85 forks, brake caliper, rotor, with a 250r wheel and hub! The rest has to fabricated......contact Jason Hall!
    1985 KXT250 A.K.A. "Doom"/Multiple Engine Combinations/Jason Hall Inverts/HRE Swing Arm, Cal Fab Swing Arm/Jemco Pipe/Buzz Saw Cylinder, Klemm Research Cyinder/PWK Carb/PVL Ignition/Dura Blue Axle/Mosh Custom Seat

  10. #10
    Join Date
    Oct 2004
    Location
    Maryland
    --
    3,077
    As bad as this sounds you need to find out how dedicated to the idea you are first. I know I had about $700 wrapped up in my inverted fork setup for my 500 and that was on the cheap side. Remember you need to re-spring the forks because typically they're too soft for a trikes use in stock form. You need the triples along with all the hardware.

    Jason has things pretty figured out to get you setup. He puts together a nice kit with the hardware, brake rotor adapter, front axle, info on brakes and he'll talk with you to help you figure out exactly what forks to buy. Etc etc. This isn't for the casual person. Be ready to pony up some bucks. Shoot Jason Hall a pm and I'm sure he'll talk it out with you in private. There's alot of thought that goes into these kits.
    And that's the rest of the story. ~ Paul Harvey

    "Yes its broken, but does that really surprise you?."
    "What happened? What does it look like happened?!?!"

  11. #11
    Join Date
    Oct 2007
    Location
    Grosse Tete, LA
    --
    3,440
    BIG FORKS FOR BIG BOYS! lol

    couldn't help myself.

    Damn I'm ready to get my bike back!

  12. #12
    Join Date
    Dec 2007
    Location
    Southwestern NY
    --
    517
    I will be running the KTM85SX forks on my Tri-Z. They are about the PERFECT length, no cutting required. And yes, Jason is building my triples as well. I should have them very soon. I scored my inverts off fleebay for $175!!!
    SAY IT!!!!!
    85 1/2 Tri-Z - The Trail Bike w/Inverts
    85 Tri-Z - The wifes Bike
    85 Tri-Z - The MX/ICE Bike, 310 w/Inverts
    12 Tri-Shee - The Flat Track/TT Bike w/Inverts

    NYTRO - New York Trike Racing Outlaws - COME GIT SOME!

  13. #13
    Join Date
    Mar 2004
    Location
    North Central Ohio!!
    --
    2,712
    Jason and I have spent the last few years refining the invert fork swap kit and if you dig around you will find that most of the swaps out there came from Halls Performance.

    Here are a few tips for you. First, ask yourself what type of riding you mainly do? If your a casual trail rider then the small forks may work out good for you, however while you will gain some smoother travel, you could very well loose some (over-all) and most of the 80cc dirtbike forks are actually smaller diameter than your stock 250R forks. If you tend to trail ride aggresivelly and/ or spend any time on an MX track, then the KTM85SX forks are the best bet. They are larger, stronger and the same length as your stock R forks. This kit is sold complete with every fabricated part you need to bolt up your KTM forks, rotor, caliper, and 250R hub. Now if you ride heavy MX or are a high speed Dune junkie, then 250/450 forks are the way to go. Long travel is the key to a super plush ride. These forks take the most work but reap the most benefits.

    PM Jason or myself for more information.
    2007 YAMAHA YTZ450 went to a great home RIP Sam


  14. #14
    Join Date
    Oct 2002
    Location
    Northeast
    --
    17,460
    I'm certain some day I'll have inverts, but I don't want to fight 100 guys over the KTM forks esp. if they need seals once a year.........

    I'd be much happier with 125 or 250 forks but I have NO CLUE how they get shortened unless I have a set here to play with. If it's a matter of chopping them down and re threading them, I'm sure I can get that done.

    Seems like the KTM forks are being bid on by everyone......

    Did KASEY ever cough up the year and model fork he figured out and was happy with??

    Never ending battle..........................
    All our government does is distract us while they steal from us, misspend our tax $ and ruin our country

  15. #15
    Join Date
    Apr 2008
    Location
    FL
    --
    144
    So I finally figured out the trick to getting the seals into the 85SX KTM forks without killing yourself and the seal...

    Have a hairdryer blowing on the fork tube for 5 minutes prior to dissassembly and re-assembly. ESPECIALLY if you are using the Hyper brand seals and not OEM. The ribs in the Hyper seals grab every little ridge on the way in and almost no amount of ing gets it back together properly.

    Heat up the tube with the hair dryer and it goes together with a minor bump. No torch needed! Makes the fork job take about 1hr total for both forks from start to back on the bike ready to ride finish.

    Also, slip a pair of shock socks on when you do the seals. That extra wiper is another barrier for that one grain of sand to get past before it lodges inside the seal and starts that pesky leak..

    Oh, spring rates.. 0.44kg/m springs for 150lb riders (like myself) or 0.47kg/m springs for heavier ones. Adjust the bottoming resistance with oil level in the fork. Works like a champ! My forks use about 75% of their travel on the woops and the last 25% soaking up the landing on jumps.

    It's almost like cheating compared to the stockers. Best money ever spent on the bike for sure! You can't go wrong with Jason's setup. I've beat on it and it's solid.

    Good luck!
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    -BFC
    '86 250R

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