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dt 250 sidehack build

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Well here it is,

Back in june Myself and a freind of mine, saw this picture

WittmanSergisJump_FH002web.jpg

well We decided that would be fun, knowing that somthing of that level would be impossible on our limited budget we decided to build one out of an older dirtbike just to goof around on. A few day later i was browsing craiglist for a decent bike to use as a base. We origonaly were trying to shoot for a big bore 4 stroke, possibly a two stoke. but i couldnt find any that were reasonable price wise. or at least reasonable for our budget. I eventually found an ad for a yamaha enduro, that was all the ad said. i called the guy and this is what he had.

246421_1983854726862_1558058754_2076189_4906278_n.jpg

Not a bad buy for 200 bucks. Soon we would begin its radical transformation.

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Are you going to do the leading link suspension? Not a bad start, should have predictable broad power being a dualsport.

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eventually that will be the plan, as soon as we get the rest of it sorted out

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Hey, this is my kind of project! There's another member on here with an old Wasp sidecar.

Make sure to hit the gym lots, even being a monkey is a lot of hard work

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yeah, we were thinking it would be alot of work, but it should be well worth it.

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200 dollars? That seems like a great deal

Well at at a distance it seems like it is. the tires are dry rotted, the silencer was clogged, fouled plugs, the blue is just cheap rattle can as well as all the black on the frame. Oh and it was missing all the parts for the breaks. so in retrospect i don't know if it was really, tried to fire it up today to ride it around and it wouldn't start after sitting for a few months, ohh well.

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I had that same bike in high school,all i remember is how slow it was...

Might want to wait for something with a little more power.

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Well here is some more progress from about a month ago, started tearing down the bike and figuring things out.

photo1.jpg

you cant really see them but weve got the floor marked with al the geometry we need. We figured, from some brief internet reaserch, that it needed to be between 45 and 50 inches wide. So that was our first mark. secondly the supossed ideal toe in for the side car wheel is about 2 degrees. with a lead on the bike rear wheel of about 8-12% of the total wheelbase. So we figured that was around 6-8 inches. Yeah i know real precise:smirk:. So after that was figured out we began bending up the first of our tube.

photo2.jpg

So this piece is going to fit from the top of the steering head down to a few inches in front of foot pegs.

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At this point you can see our innovative suspension design in the works. That is a 1974 xl 350 swing arm and rear wheel. Traditional sidehacks use a single trailing arm and a spindle to mount a 16" or similar wheel to. We figured however since we are not machinist's and don't have the materials to properly make a strong spindle we would just use a swingarm i had laying around and go that route.

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I had that same bike in high school,all i remember is how slow it was...

Might want to wait for something with a little more power.

We figured we would use this motor for a bit and see how it goes, eventually it will be swapped out for either a yz/it 490 or a tt500 motor if it will fit.

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If you had the xl350 it would probably be a better starting point. I see where your going with this. Clever.

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So it continues, i can't seem to locate the pics of us installing our "high tech" suspension, but it wasn't supper difficult we used some premade A&A tabs drilled to the appropriate size for the swing arm bolt. This made it relatively easy, the hardest part was getting the camber right about 1-2 degrees top leaning in, if that makes any sense. I also bent up the main floor hoop. at this point the platform space is about 30"x30" which should make it easy to do aluminum floor down the road. Having the floor done we were now able to build the main shock hoop. we are going to use a 13" from a xl 350 as well. We mounted it close to vertical, sacrificing travel for a much more constant spring rate, this should help keep the handling more predictable. here is a picture as of right now.

photo5.jpg

And yes i do realize it is not good to weld without both a helmet and gloves, I am just taking it in, I am not looking at the pretty blue light.

photo6.jpg

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Looks good so far!!

If you can get your hands on a 75-mx400 or 76 yz 400 motor (same)

it will fit in that frame. Or even a 75 mx 250 (like my bike)Is WAY faster but still the same base mounting design.

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That is a bitchin truck in the background. Looks like you guys keep busy!

Are you going to gut the back wheel of the sprocket and brake, or run a dual brake setup?

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Hey thanks, yeah thats a family freinds jeep my step dads been building,

we'll probably lose the sprocket and the breaks, though it might be cool to have dual breaks then it would make very sharp right corners.

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Well heres the progress thus far, Added a brace for the shock tower this should help give support to the floor as well, it flexed a little to much for comfort.

PA050418.jpg

We then added the bars for the aluminum on the floor, This made it seem a lot more complete. i added a brace from the rear sub frame connecting to the front of the shock tower, this not only served to brace the whole chassis but would provide a spot to mount the handle as well as being able to give the driver enough room to maneuver.

PA110419.jpg

you can see the under engine chassis brace we added to give more strength to theframe

PA110420.jpg

Next step is to build the handle, add more frame gusseting, tabs for the aluminum, and the aluminum its self, paint and reassemble. Hope fully in a couple more weeks it will be done.

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Looking awesome. Is the engine in good working order or are you tearing it down?

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Looking awesome. Is the engine in good working order or are you tearing it down?

The motor is out just so we can weld around the frame in that area, and to make it lighter for rolling around the shop. However this weekend i threw it back in to start it up, and it wont start. don't really no whats wrong, its getting spark and has a wet plug, haven't checked to see if its just residual fuel in in the case or fresh fuel from the carb, so i don't know if its getting fuel or not. Any suggestions?

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