Swamp Donkey 2.0 The BW200/XR400 Makes the Rockin World Go Round'

Hurco550

Keep er' Between the ditches
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As some of you know, the first iteration of the fat tire swamp donkey built from a krusty tw200 and bw200 parts went to live out its days under the slaving hand of Deviant1 as a Gulf Shores Beach cruiser. If anyone wants to catch up on that build, its here:
http://www.dotheton.com/forum/index.php?topic=75455.0






While the original swamp donkey is where it belongs and with who it belongs with, its absence has left a fat- tire-bike shaped hole in my life. I recently found a deal on a 1986 BW200es close to home for a fair price given the current market on these machines. It was complete and did not appear to be overly abused, coming with a stack of receipts from the original and second owner.







Once I got the bike home and fired up for a test ride, a few trips around the parking lot behind my house coaxed a few issues to rear their ugly head. The top end valve train was making some VERY unsavory noises, and there was so much oil puking out of the air box from the crank breather from blow by that you could track the route that I had taken around the parking lot. Long story short, the motor needs a top end overhaul. That is all fine and well, they are simple motors, parts are easy to find etc. The only caveat is that while riding the tw200, which is the same power plant where it counts as the bw200, is that while its power output was adequate to haul my 260 lb self around, adequate doesn't always equal fun. Sure it pulled me up, around and through the Mid Ohio hare scramble course without missing a beat, but it did so much like a lawn mower would. No frills, just chugging. Just like any good red blooded American, I want more. I need EXCESS.

Enter the Honda XR400R powerplant. This engine has alot going for it, but mostly the 34 H.P. compared to the 15 H.P. of the BW200. The other thing it has going for it is that it fits in the frame of a bw200. I found a this picture on a bw200 facebook page of a guy who put the engine out of a 400ex into a bw200 chassis. The 400ex is a very similar motor to the xr400r, with some differences including electric start vs the kick start only of a XR400. Below is a picture of the 400ex swapped bw200. I like that this picture proves that it fits, but I will not be doing the goofy swingarm stretch or dropping the front end. I still want this machine to be able to eat up the single track.




After deciding the route I wanted to go with an XR400R powerplant, I decided that I'd casually keep an eye out on craigslist and facebook market place for the right donor xr400. The universe had other plans. I was meant to find THE PERFECT donor sooner. That day in fact. While cruising along, I found an xr400r Parts bike. It was the frame, carb, ignition, oil cooler and motor. Perfect for an engine swap, and I don't have to feel bad about pulling apart a complete bike in order to complete my goal. Better yet, the whole xr400 pile was $150, which added to the $450 purchase price of the BW200 only puts me at a net total of $600 into this whole project so far. If I play my cards right, ill have a really wicked machine for under $1k. I have not yet decided how I am going to go about working past the oil in frame issue of the xr400, but there may be a bit of frame grafting going on between the xr400 frame and bw200 frame, but I will keep that up to date in this build thread.

Here is how the xr400r came to me after a 4 hour round trip down by Urbana last night:




So, pull up a chair, and follow along with the next hair brained project out of Hurco's Garage. Like all the rest, progress will likely be fast and slow, then rinse and repeat.
 

SONICJK

Reminds me of...me No, I'm sure of it. I hate him
Niiice.
Why not just swap the 200 forks and swingarm into the 400 frame? Is it that much bigger?
 

Hurco550

Keep er' Between the ditches
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SONIC. said:
Niiice.
Why not just swap the 200 forks and swingarm into the 400 frame? Is it that much bigger?
That may be a possibility. I will not know until I get the bw200 stripped down and get them side by side. I would still have to hack the rear half of the bw frame off and mount it to the xr400 frame to utilize the odd dual rear shock setup of the bw200 swing arm. Another thing is that i still (at least at this point) want to use the bw200 body work. The rear fender and side panels work well together, and they are super wide to accomodate the almost 12" wide rear tire. I found out at Mud Ohio on the first swamp donkey that a wide rear tire is the way to go.

Using the neck and cradle of the xr400 frame would also simplify the oil in frame issue. Ill have to look at rake angles as well, as the xr400 is a pretty steep 25 deg stock. Not sure what the bigwheel is, but ill find out tonight when i put an angle finder on it.
 

ridesolo

You only bear responsibility for your own actions
Nice. This will be good practice for putting "other brand" single cylinder engines into different brand frames. You never know, that might be a skill you'll need in the future. Keep this up and you're going to become known as "The Transplanterer."
 

SONICJK

Reminds me of...me No, I'm sure of it. I hate him
Sounds good.
Oil in frame could also just be an oil tank as well if there's a decent spot on the BW to put it
 

Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
SONIC. said:
Sounds good.
Oil in frame could also just be an oil tank as well if there's a decent spot on the BW to put it
sure could, and that's an option I'm willing to explore. I also like the idea of using the xr400 for the fact that it makes the oiling system problem even easier, especially with the super cool xr400 oil cooler already incorporated lol

I will take the easiest road, whichever it is.

"give the laziest man the hardest job and he will find the easiest way to do it"
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
It won't work. An XR400r has two exhaust ports, which means it's weird. You can't have two exhaust ports and fat tires on the same bike, unless you use Firestones.
 

Hurco550

Keep er' Between the ditches
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irk miller said:
It won't work. An XR400r has two exhaust ports, which means it's weird. You can't have two exhaust ports and fat tires on the same bike, unless you use Firestones.
That's it, it's all going in the scrap hopper.

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Hurco550

Keep er' Between the ditches
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Ooh I'm gonna do it, then I'm gonna roost irk with it. Mark my words lol

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Popeye SXM

Also used for MX
I'm in. I wish i could get back to my DZR big tyred monster. Did you ride your original swamp monster on hard ground?, I am curious about the handling. Looks like a fun project. I made a custom swing arm as the BW200 is super WIDE. Good luck
 

Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
Popeye SXM said:
I'm in. I wish i could get back to my DZR big tyred monster. Did you ride your original swamp monster on hard ground?, I am curious about the handling. Looks like a fun project. I made a custom swing arm as the BW200 is super WIDE. Good luck
Handles surprisingly well actually. On asphalt the at full clip (about 50mph I'd guess) the fat front tire starts to wander a bit, but it's super stable at slow speeds.

Edit: I would also love to see your swing arm setup. I'm not against using a narrower wheel and tire combo out back, even if it means fabricating a swingarm. Are you still utilizing a jackshaft?

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Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
Per the norm, there has been a bit of a "change of plans".....

I have stared at the xr400 chassis next to the bw200 long enough to come to the conclusion that I will be better off to use the xr400 frame and build it into a fat tire bike vs putting the engine into the outdated chassis of the bw200. I WAS planning on gutting the bw200 to do just that. Even though I'm far from a purist, I cant let myself cut up a fairly solid old complete survivor. I have decided to sell the bw200 complete and use the proceeds to buy the specific parts I need to complete this project.

The (current) plan is to now use a tri z three wheeler front wheel/ hub and rotor. The rim itself is identical to the bw200 (same part #) but the hub is cast alloy instead of welded steel on the bw200 and it is disk brake. (im currently the high bidder on this one on ebay...)

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I plan to mate this to a set of rmz450 usd forks that i've had around for a while. I will make a custom set of triples to offset for the larger front tire and also make them utilize the stock xr400 stem.

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The next project will be to make a swingarm instead of using a bw200 swingarm. Mine will be mildly based on the honda missle swingarm. The missle kit was available back in the day to convert honda atcs (i believe mostly the 250r) into fat tire dirbikes. In this way i can make it narrower than the bw200, and also get rid of the strange cam/ bushing combo to tension the short chain between the engine and jackshaft.
 
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