Because I don't have enough to do, building new frame for my Ducati.

jag767

Over 1,000 Posts
Almost a year ago when I started to build my ducati 160, I scrounged up parts around the shop to make a bike to go with the motor. I never planned on this being it's final form, but since people seemed to like it so much I haven't changed it. Well, that's about to change.

A couple of days ago I pulled the engine for some more aggressive top end work, especially since I have resources available to me I didn't have previously to really get it right. While it's out, I started playing with the build a whole new frame idea again. My goal was to come up with a simple design that I could build without a frame jig, using only a tube roller and hand cutting all my notches. After a little playing around, I've done just that. My plan is to make everything other than the swing arm a single tube, so I can draw it out with the correct angle/radius, and just lay the parts on the drawing to confirm its correct. I've seen some builders to it this way with success.

Best I can tell with 2" .125 wall tubing, using the frame as a stressed member, I'll be good to go. I think the end result will be a bit lighter, but more importantly it will look awesome. I just ordered the tubing, plan is to screw around this weekend. In the mean time I'm open to suggestions, especially on the rear monoshock, front end, and wheels. I'm really trying to keep this lightweight, and I'm digging the idea of a supermotoish style.

Here's a very crude sketch of what my initial idea is.
 

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Looks like a cool project. How will you ensure the headstock is true to the swingarm pivot without a jig?
 
doc_rot said:
Looks like a cool project. How will you ensure the headstock is true to the swingarm pivot without a jig?

It's all gonna be flat since it's a single tube and I'll tack it right to the table. That's the main reason I'm making everything from 2 inch tube.
 
And already I screwed up, er kind of. Ordered 2 inch material for the neck so it would be uniform with the frame, and the neck bearings are a smidge larger than the steel. Luckily I have 2.5in 7075 billet aluminum laying around, so I will undercut the neck to account for the length of the aluminum cups I will add. It'll actually look pretty cool in the end, I'll turn a nice radius onto the outside of the cups, much easier than having to do it to steel anyway. I'll machine it extremely tight and press them in, should work well from what I gather. I need the finished outside length to be 6 7/8".
 
Evolutionary design, it’s what garage builds are all about!

A colleague left the company we worked for designing off highway machines and went to work (at the same site) for Royal Enfield, he’s mad keen on bikes and I really hope working in the volume industry doesn’t beat the love out of him


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Yup, this is evolution all right. Spent a little time on the lathe, but got cut short. Once I get a couple more hours in I'll get some pretty photos on here. At the risk of being ridiculous, I think i'm going to use the overkill spare 998 front end I have, and make the needed parts to run it with a front drum. Ironically, being much larger, it's not much heavier than the little 31mm I was using. I'm hoping it doesn't look silly, definitely going to give the bike an English bulldog-like appearance.
 
Got some lathe time in last night, and figured out exactly how to make the parts of the neck with a little trial and error. Now that the error is out of the way, I will finish up the parts tonight. Should look pretty awesome for a neck.

Since i promised photos, heres the ducati front end im using.
 

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DesmoDog said:
All this for a 160 engine? I had a 160...

Boy, you ain't quite right. ;-)

Lol I really like the little guy. That and I want to build a frame for the sohc cb750 motor I picked up, and this seems like a fair stepping stone.
 
Well this just took a violent left turn. While I do want a different frame for my 160, through a series of semi logical events, I'm going to use my m750 motor for this instead. The short of it is I wound up with different wheels, and at this point all I need is a seat and tank to have an entire second bike. I hate my 750 other than the motor, and have intended to make a frame for that too, and I figured out an awesome design which will still be doable without a jig. It's hard to follow my chicken scratch drawing, but the downtube, backbone, seat post, and radius swinging into it are still a single tube. The 2 radius (what's plural for radius?) Going down between the backbone and downtube will be on each side of the motor for motor mounts. I need to make sure the strength is there, but I think it'll work. I finished making the neck (pictures tomorrow) so next my buddy will take measurements for this and make a model so we can get exact figures to build the frame.
 

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Step 1: Bolt engine into the jig.
Step 2: bend tubes to fit around motor
Step 3: weld in the jig

Did I mention getting a simple frame jig? ;-)

If you were closer to Chicago, I'd lend you mine for a couple of weeks.
 
For a 160 it's not so important but for a fast bike with high stress cornering, maybe a jig's a good idea. Where are you located BTW?
 
I'd say there's a 85% I use the 750 motor, the 15% is in case I get lazy. Im in NY, specifically long island.
 
THat's a bit far to drop in to borrow a jig. Maybe there's a new frame jig in your future. Mine is from Chop Source plus a few lengths of 2x2 and a few other sizes for feet etc. They are a simple basically 2 dimensional jig, but adequate for simple frames or modifications. The hard part is keeping the frame from wondering off to one side or the other, so take your time with that.
 
If you have a steel fabrication table you can always just use some cones and some all thread. That's what I do anyways.

For anything that needs precision, a proper flat table is a must though. I've seen race cars built on tables that were +/- .0025" over 12 feet, it's the right way to do it.
 
Well i stopped fuckin around and ordered a jig. I also picked out wheels. Its a long story but im using kx250f hubs with excel 18x2.15 rims. At this point its 100% im using the monster motor, so it will be light and fast for what it is
 
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