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CRF100 w/CR85 suspension Hybrid

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Whats involved in putting a CR 85 "Big wheel" swingarm on a CRF100? :D I have spent many hours reading threads and doing searches in this forum. If I missed something, it's not from a lack of trying.

I went to the Hatfield-McCoy trail system (in WV) in June with my ATC 250R. I quickly came to the conclusion that I didn't want my son doing mountain decents with the drum brakes on his CRF 100. The bike is great except for the brakes.

I see where riders have modified the CRF with the CR 80/85 forks. They will add a BBR swingarm and a Works shock. Thats at least $900 in the rear end, and they still have the rear drum brake. Then theres the other group of Mavericks who stuff the 4 stroke engine into the CR chassis.

I saw a complete kit on the web for about $1500. It had everything to graft the CR85 suspension, wheels, and brakes onto the CRF/XR 100. I didn't pay much mind to it then, but that is probably the only example of such a process I've seen. I have the CR forks, swingarm, & disc brake systems.

It can't be rocket surgery, but I haven't really seen many of the rear conversions with the stock CRF frame. Fill me in guys. My boy isn't going to jump too much on purpose, but I'd like for him to have a spiffy ride that actually stops on command. Thanks for your help!

Regards, Thomas

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I haven't seen any stock 100's with the cr swingarm and disc brake set up. Most people do the CR forks and disc brake set up. Most of your stopping power is with the front anyways. Doing the rear you have to also find a spot to mount the master cylinder on the fram, adapt the linkage, etc. Come to think of it, I think there was a guy on here with a road race bike that he did do this mod, so maybe he will see this.

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I haven't seen any stock 100's with the cr swingarm and disc brake set up. Most people do the CR forks and disc brake set up. Most of your stopping power is with the front anyways. Doing the rear you have to also find a spot to mount the master cylinder on the fram, adapt the linkage, etc. Come to think of it, I think there was a guy on here with a road race bike that he did do this mod, so maybe he will see this.

Pretty sure that was a CRF150,,and ya it was a SM bike.

If you can get your hands on a CR85....the real deal is to put the 100 (105, 110, ect ect) motor in the CR85 rolling chassis.

Great suspension, brakes, nice strong 4 stroke motor...Wish the OEM's made one :D

EDIT: Here is the rear disk on the CRF150 I was refering to

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Yeah, the work to adapt a CR swingarm would not be worth it, compared to a simple conversion. Plus, the benefit of the conversion far out weighs anything the 100 would do. With a conversion you get a bigger airbox, which eliminate a lot of jetting issues, disc's front and rear, real suspension and linkage, a frame and swingarm that doesn't flex like rubber, and it is balanced. You just bolt on your stuff and go. Actually, valve the suspension then go.

If you want brakes, get a front disc. You should never really use the rear to stop anyway. It's about 80/20 front to rear. Just get a set of 1995 and under cr80 forks, have them shortened and get a front 19' wheel off a 1996 and up cr80/85. Your bike will work and brake much better with a lot less hassle. get a Works shock too.

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Thanks for the link. For now, I'm planning the design & conversion. This is for my son's 1st trailbike, so I don't want to go nuts just yet. Stuffing a 100 thumper motor into a CR chassis seems like a hassle to me...I haven't tried welding either. I've been buying CR parts one by one. If I had the dough to get the whole sacrificial bike and a TIG Welder, then I might consider it. I have access to a machine shop at work, and 3 metal lathes here in my home shop. Fabricating the spacers and brackets should be the easy part. It would be easier if I had the whole CR85 to use for reference. I guess I'll take my dial caliper and protractor to the Honda shop to get the critical measurements and angles and go from there.

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Why don't just fab the disc brake on to the stock 100 swingarm. That would be a lot easier that the whole swingarm. But let us know how it comes out.

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Banke performance makes a disk conversion for the xr100. If you have the cr80 brake and wheel set up all you need is the brake bracket and wheel spacers.

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I have a pair of 2000 CR 85 Inverted forks. Can they be shortened? How much would that probably cost? I found an article on lowering Sport street bikes, they estimated shortening by a suspension guru to run around $300. I'll have to see how it sits with front and rear mods, before I put a Maltese Cross on the numberplate.

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Yeah cr85 forks (any fork) can be shortend. Just call up a suspension shop.

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Have you considered just buying a used CR80/XR100 conversion bike? Since the 150R came out they run about $2500 +/-, sell your XR100 and you've got your son on a dam good bike for $1500.

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I am debating on selling mine. I have had it several years and have ridden it several times. I ride my big bike most of the time as that is what all my friends have. Here is the most recent picture I have (from last year). Cosmetically it has changed and it has a BBR pipe on it now. It is a DMC frame, LA Sleeve 120 kit, 200x carb and all the goodies seen like wave rotors, CRF450 master cylinder, gold wheels, etc. I am open to offers.

DSCF0002.jpg?t=1178222278

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here is the deal as i know it. I just built two bikes, one is a stock 100, the other a DMC 120 ,cr80 conversion. The DMC bike: $1600 for a ridden twice '02 cr80 $1600 for the DMC kit, $400 for a like new 2002 XR 100 motor (ebay).$1800 for a Engines Only stage II with all the bells and whistles. $40 for a 2002 XR100 fuel tank ( ebay) . New chain and sprockets, top triple clamp and bars, wiring harness, this thing cost about $6000. (it is new, and very sweet!!!)

The XR100: New bike, $2000, BBR frame cradle $190. BBR swing arm $500,then now i think i heard here they are custom orders and run about $800?. Works shock $400. 1995 Cr 80 forks, custom top clamp,custom stem pressed into lower clamp, cone bearings,Later model big front wheel,Race tech cartridge emulators, front brake,and rebuild kit. I cut the springs and made some spacers. The front end i think i'm in about $800. Pipe $100. Motor is stock right now except for air and jetting. All up about $4790.

There is someone on the forum who fabed a cr80 rear end to a stock 100 frame. i forget who but you will find it if you do a search. The best is to check out our own SoCal XRs web site, There were a couple of sweet looking conversions there for $2500 in the classified section. It was great fun building the bikes,and you dont have to take it as far as i did, but there is a little more than meets the eye to any of these mods. Remember a stock 100 has good resale, $6000 conversions are $2500 used and a new CRF150R is about $4200.

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$6000 conversions are $2500 used

Exactly!! If I hadn't already built mine I'd be looking to buy a conversion now. The bikes are fun. Zicazoo, here's a price breakdown on my conversion:

$1100 for a 97CR80, 1600 for the DMC frame/exhaust, $2000 into my old XR120, nother $500 or so in miscellaneous odds/ends, -$500 for selling the CR80 motor, -$250 for selling the old XR100 rolling chassis ... total - ~$4500!!! Used conversions are bargains right now.

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Go with the motor in the CR chassis you will love the benifits. Who wouldn't want a XR with:

11" of suspension travel vs 5"

Disc brakes vs Drum

13.9" of Ground Clearance vs 10"

15lb lighter

MUCH more power

And I just happen to have one for sale...:applause:

XR 115 BIG VALVE motor in a CR80 Expert chassis and done so well by DMC that it looks and performs like Factory Honda did it.

This is a 115 Takegawa big valve superhead big bore kit, performance cam, light fly wheel, modified XR200 carb, new main bearings, high performance oil pump, oil cooler, even a new heavy duty kick start gears all done by John Cartwright ( motor only has about 2hrs on it), susp. by JM Racing, new clutch, new chain & sprockets, fast line brake line. Awesome race or play bike.

Have pictures.

Price, about what an new CFR100 is out the door: $2500 O.B.O.

Phone: 281-569-3321

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