There is a little bit of this bike I don’t like, the back bit. I don’t like the way it sits, the motor is suspended by its mounts under the spine of the frame and then is just turns to blah.. Comfortable sure, but the way it is visually waited makes the bike look sluggish and heavy. If your bike is going to look heavy at least give it a presence, a stance. So I am going to attempt to do that. Exhibit A: The “Just Blah Frame”
It looks ok now, without the battery, airbox, carbs, seat or muffler. These things do not add much weight but they do make the whole thing look solid. I things to be form following function, but I will admit, I like things to look as functional as they are… useful
So I give you:
With the Ducati Hypermotard rear shock that I scored off Ebay.
And this is how I did it. Perhaps not the best way, but the way that worked with little to no damage to the frame it self:
First I took the coils off and the carbs and the rear portions of the wiring harness. Then I took a whiz-wheel (cutting disk) and cut through the upper portion of the frame just after the triangle made by the pipes coming off the spine of the frame, next I cut off the lower portion of the frame where the swing arm pivots are held in place.
If your cutting wheel can not make the distance around the bottom section ( mine couldn’t) Chop off the frame where it is still round, and then slice into the box section-tap with hammer until the slot you cut is wide enough to get to the other side.
The really fun bit is trying to get the top of the rear section of the frame off without damaging the spine. I first cut away at the welds holding the small section of pipe that one of the engine bracket mounding bolts slides through. After that looked relatively free, I went at the top of the welds until I believed I was through. As soon as I thought I was, I took a pry bar (old flat head screwdriver that I could hit with a hammer) and hit it with a hammer into the groove I had just cut; working the welded bit of formed pipe (which turns out to be a couple layers of pipe sandwiched together) away from the frame. I kept this up until I could get at the lower welds from the top with the whiz-wheel.
After, just a few passe with the grinder to smooth things over and a blast of chain lube to keep it from blooming into rust and that bit is over. Next will be the lining up of the shock and then getting my tig welding buddy to come run a couple passes to tighten it all up. Starting with the bottom I cut some 1/4 inch plate to shape, centering it with the proper sized diameter hole. On tacking that into place, lined up the upper mounts. I am using a stacked box design. I cut and ground the plates to line up in a pseudo streamline pattern and then put them into place. I am not going to tack these right away, still have to grind the paint away, but I also want it to be super clean for my buddy to come TIG it all up. His bike is the KTM inbtween the CX500s. Making the plates was time consuming, but setup always is. might as well make it all fit first before you weld it into place…
Cardboard is king. Making the stencils for the plates and lining them up on the bike makes for a better end result. The circles drawn there were for lightening up the mount. But without the tools to flare out the edges of the drilled holes to add strength, I decided to keep the solid steel bars as is to keep them as stiff as possible.
The extra stack is for strength and providing a place to mount the seat and the rear of the gas tank. All that is left on the mount is to set up a place to bolt the tank and the seat. And this is where I cheated a bit. I do not weld particularly well. So I enlisted the help of a welding friend, Brian O’Neill. He popped by, had a look and then said he would be back. We had to get the bike to his shop to use his welding set up and because it was a substantial 50 degrees warmer than in the basement of a barn. So, after manhandling it up the hill and into a pickup truck, we drove it over and manhandled it out of the pickup and into the shop.
The first order of business was to knock off the previously tacked lower brackets and re-prep them. We took a centerline off of a piece of string that we eye-balled from the centerline of the rear tire and the center of the fork crown. After taking the pieces into place for a second time, he laid some beads down to lock the flanges into place. using the bottom as the pivot point, we lined up the top of the shock to the frame and tacked the top brackets into place. Removed the shock and welded them into place (the heat transfer from the brackets to the bolt to the bushing in the shock is rapid and may result in the frying of the bushing). After this we added the top of the brackets where I forgot to bring the top piece where the seat and rear of the tank will bolt down.