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Discussion Starter #1
I recently picked up a 71 honda CL100, from I guy I work with. The bike looks like hell but was only 40 bucks. I want to build a cafe racer with it and I was thinking of going 2-stroke. I want to get either a cr125 or cr250 dirt bike engine. It will mostly depend on what will fit and what i can find. My questions were is there an immediate problem with this idea, and how does one power a head light with a dirt bike engine.
 

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Hey Benjamin, I was going to do the same thing with my cl175. It,s getting harder to find a good deal on a 2stroke motor, the shifter kart craze has sent the prices through the roof. There are still deals to be had if you look hard enough though. There are a couple of companies that make Baja lighting kits for the popular models like cr's. Cant remember the names right now but wont be hard to find. Wont be a difficult swap, just fabbing up the new motor mounts and making shure your chain line clears the swingarm and the sprockets line up. On some years of some cr motors the drive output is on differant sides of the motor, something to keep in mind. Good luck and keep us posted!!
 

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Ben,
Don't want to discourage you...but I think that swap would be a tremendous pain in the butt. The CL100 has a single downtube frame that ends at the engine, the CR's use a cradle frame...the geometery of the engine space in the frames are totally different.
Only feasible way I could see to do it short of having a machine shop is to get a CR frame and cut out the section of frame that mounts the engine and graft it into the CL frame.
Might be easier to convert a CR125 into a Cafe.

The upside is....if you are going where I think you are going...is one bad ass little 2 stroke 125cc Cafe bike that you could sneak past the authorities using the CL frame numbers for registration and such. With the proper work you could have a 120mph CL100 :).

If I had a ton of spare time and a lot of tools (I do have the tools)...yeah I guess maybe I would give that a try. You'd want to update numerous suspension components on that CL frame to handle the HP and speed of the CR engine.
JohnnyB
 

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im planing on taking my CL125 for a LSR in the fall with the 4 stroke. should go fast enough.
a SL frame would be better. there is on on ebay right now in CT for almost no money.
was the 100 motor running? i where are you? might be interested in the left over 4 stroke parts....

There is the right way, the wrong way and the british way to do anything!
 

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Discussion Starter #5
What is better about the SL frame? I am located in wisconsin, known for its long riding season. I think i am going to keep the old engine for a while atleast. I dont know if it runs it was not a real big concern of mine upon time of purchase.
 

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the SL frame wrapps under the motor. could be easyer to mount the CR motor

There is the right way, the wrong way and the british way to do anything!
 

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another idea...if you want to go two stroke with out a charging system you can always go constant loss electrical just to pass inspection. or look out for a two stroke trail bike which will have a lighting coil on the magneto. whatever the case, you are looking forward to a considerable time investment. if you love the work, it will be fun. if you don't like to problem solve and fab, you'll never get done. Dr. b. knows the deal and has made a few false starts over the years i'd guess. it's how you get better. just a few thoughts.
parks
 

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Discussion Starter #8
Time is not an issue, money always is. I wanted a project with a lot of fab work, and as far as problem solving I am an engineering student so i love that stuff. And i like to weld.

Are the trail bike magnetos interchangeable with other bikes.
 

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so that you avoid interchangeability issues, it's usually easiest to use as much of the wiring as possible from the motor's doner bike, especially handlebar switchgear, and loose the wiring from the bike (frame) you're sticking the new motor into. brake light switches are easy to re-invent and usually neccessary to redo anyway do to the rearset/footpeg mod.s you're in for. mock up engine early on to check for chainline issues (swingarm travel along with right/left alignment as fatguy mentions... really hard to correct after you are too far down the line.
parks
 

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Discussion Starter #10
i was originally looking for an engine but I think know i will look for a salvaged bike so i can get the engine and wireing and use the throttle and brake parts.

The handle bars on alot of the racers i see look like they have been simply inverted, is that true or are some of them custom built.
 

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Benjamin,
I don't know how far you are able to travel, but if you check out e-bay in mtorcycle parts, do a search for parts bikes. I found several 125-250 2 strokes in WI and IL. You might want to consider a Yamaha DT 125 or 175. They have full electrics and would be a good srting point. The later 175s even had monoshock rear suspension that you might be able to adapt. It could all be a good project. I see you are at UW- Plattville, and one of the bikes I saw was in Reedsburg, so not too far away.

Ken

AHRMA 412
Vintage racing - old guys on old bikes
 

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Discussion Starter #12
I like the idea of a mono rear shock, but all the pictures on this forum have dual rear shocks and I like the older look, I plan on upgrading to something newer and stiffer because I doubt the suspension I have was designed for a 180lb guy riding on the rear seat with potentially 4 times the power if I go 250cc.

And as far as traveling to get a bike is not a problem last week I moved around mine and my buddies bikes borrowing my dads truck.

Again thatnks for all the help.
 

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Benjamin,
My first design parameter would be to decide if I was gonna go air or liquid cooled. There are lighting kits available for most modern MXers, www.trailtech.net or Baja Designs. Downsides are; mounting radiators could be a pain, modern two strokes put out enough power that everything on the chassis would have to be upgraded, and of course cost. If you're willing to stay air-cooled look for something like a complete IT or KDX 175 as a donor bike as they have lighting coils and are cheap. http://cgi.ebay.com/ebaymotors/1982...tegoryZ35595QQihZ015QQitemZ250100097095QQrdZ1

04 KDX 200
05 KX 250f- SOLD!
01 GSXR 750
75 GT 550
68 Chevelle
 
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