No matter how I reoriented the engine and torque converter, something ended up bumping into the frame somewhere: the flywheel, the cylinder head, the starter motor. At one point, I was willing to lose the electric start if that would have allow things to go into the frame, but ultimately that wasn't a magic bullet.
So, after a bit of measuring and a long time staring at the frame and trying to think things through, I bit the bullet and whacked the down tubes off. With that done, I could prop the engine up on wooden blocks to figure out where it had to go, in order to figure out where the frame could go.
The engine was inclined at 10.9° forward, nicely within the normally accepted 0° – 15° "safe" range for a GX clone/Pedator engine. As the bike sits, the lower frame tubes of the SST frame are –9.1° from level. The forward seat tube is 36.05°, and the top of the cylinder head is "eyeball close" to parallel. The GX/clone engines have the cylinder inclined 25° from horizontal, so my numbers all check out:
So, my next step is to make an engine mount with an included angle of 20°, and get everything bolted up with the torque converter sprocket properly aligned.
After that, I will have to figure out how to configure replacement frame tubes. For this, I'll be using the Ridgid #368 bender (3/4" OD x 3.75" radius) that I bought to modify Bultakenstein's frame. I got a cheap score on a few 3-foot remnants of 0.75 OD, .065 wall, unspecified "carbon steel" tubing. The existing frame tubes are 7/8" OD x 0.95" wall, so these are thinner and the smaller OD will be a visible mis-match, but so be it. For what a different mandrel bender would cost, I am super okay sticking with the OD that matches my tool. Even the tools for this project are whatever I have lying around. And even though my bender is rated for up to .120 wall, the 0.65 will be just fine for this application (and as a bonus, super easy to bend!).
Yeah, I came to the same conclusion. I just ordered some lengths of .109 wall 1026 DOM off EBay. I figure, I'm only going to modify this frame once. If I'm going to go through the effort, there's no reason to use flimsy mystery metal.
I had to take a break from the workshop for the usual homeowner tasks, a couple of family gatherings, plus some travel. I'm the guy behind the annual Smackdab Summer Solstice Run, and my wife and I did the ride on our Can-Am Spyders again this year.
Last night I was finally able to get back to The Bride's fame mods. My Ridgid ratchet bender coped with the thicker .109 wall tubing just fine. Trying to judge the springback was a bit of a wild guess. I had taken the time to throw some math at the problem, and I was pleased that I was able to replicate my pattern pretty accurately.
It will need to be trimmed to fit, obviously.
I only had time to get the first one bent. I'll give the other side a go sometime in the next week or two.
So, I have both of the downtubes bent to fit.
But how do I go about inserting a slug into both ends of the tube simultaneously?
In the past, I have typically left a sizable gap between the tubes I was joining. That way, I could insert an extra-long slug into one tube, slide it partially into the other, and weld the slug separately to each tube. Unfortunately, that ends up with a skinnier section in the middle that looks pretty cobbly. Since I already have two different tube diameters here, I really didn't want to do that this time.
So, there may be more straightforward ways to do it, but here's what I came up with:
First, I turned a couple of slugs that are the ID of the frame tubing on one side, and the smaller ID of my new tube on the other. Note that one of them has a little lip or collar in the middle, and one does not.
I bored a big hole in the bottom of the one without the retaining collar and silver soldered a length of 16 ga. automotive wire to it.
I drilled a small hole in the bend of the new tube, and threaded the wire through it. I also drilled a hole at the very end to create a notch for the wire.
On the bike, I fitted the slug and tube to the bottom frame tube first. The lip keeps the slug centered at the junction point.
At the other end, I slid the slug fully into the downtube, moved the tube into position, and then pulled on the wire. The difference in inside diameters prevents the slug from coming too far, and my little alignment marks show when it is fully seated. Gravity will help it stay in position until it gets welded.
And now it's locked in place and ready for welding. After I do the same operation on the other side, I will drill a couple of additional holes in the frame tubes and plug-weld each of the slugs through the holes on both sides of the joint.
Below, you can see my little, blue, 85-amp Clarke spoolgun welder on the right. I have a big bottle of 100% argon hooked up to it, which is great for welding aluminum and MIG brazing, but no bueno for MIG welding steel. Under it on my welding cart (hidden by the trash can) there's also a H-F Titanium 125 gassless flux-core welder. I'm undecided whether to: A) try my hand at silcon-bronze MIG brazing around the diameter of the joints; B) flux-core weld the whole thing with the Titanium 125; C) spend the money for a bottle of 25/75 MIG gas; or, D) take the whole thing to my friendly neighborhood welding shop.
It’s a snug enough fit and the inside of the original frame is fairly rough in spots. It wouldn’t have just fallen into position without a bit of persuasion. I had to give the wire a couple of healthy tugs to get it fully seated.
I like it. It is an interesting mix of stuff. But I would think that the angle of the engine will lead to oil starvation as well as a lot of oil soaking the cylinder to the point that the rings wont be able to control it. I dont think the rod will last long enough for the rings/cylinder to be much of a concern though. Just my thoughts.
A bit of chamfering, and it looks factory! Not having had much technical training in life, I so enjoy owning a lathe. Even though I'm doing super-basic stuff here, I still can't help but feel a sense of wonder that I can form and shape metal parts. Not only can I do it by myself, I can do it pretty damn accurately.
I've never heard of silicon bronze MIG brazing, but i keep some silicon bronze filler wire on hand for TIG brazing.
If it were me, i would spring for the MIG shielding gas, but you said your welder is only 85 amps. Can you attach a bottle to your 125 amp machine?
Also i like the way you made those plugs and soldered the wire, cool idea.
I used my HF Titanium 125 to tack in my frame tubes this morning before work. It was my first time striking an arc with the thing and, for FCAW, it works surprisingly well. It'll never make a real welder out of me [If you gotta grind down your welds, you're a "grinder," not a "welder"], but for simple plug welding and a couple of tacks, it was easy-peasy-cheddar-cheesy. I'll eventually take it to my local welding guy to get finished correctly, but that can wait for now; I have the tank mounts and rear suspension to do, and those will require additional welding. In the meantime, it's on to fabricating the engine mount.
Not a great deal of progress, but managing to give this a bit of attention whenever I get a spare moment. I'm currently using scrap to mock up the engine mount and determine the precise dimensions needed. I picked up some metal plate stock and ordered a bending brake attachment for my hydraulic shop press; I hope to have the design finalized by the time it arrives.