The little Ducati Featherweight

Tune, that's a great tank and the single is amazing. Looks a little flexy around the swingarm pivot.

A new thin wall chrome moly frame would be the way to keep weight down. CB160 frame is much lighter than a 175, but make a replica to suit and save more weight. Check out a Laverda twin frame for a similar look but stiffer. That might be harder to scale down and replicate, but it's neater than a CB in many ways.

That Joe Biden ( load of Malarkey) frame is probably the stiffest and lightest ( and simplest) design, but hides the motor which is way too pretty to put behind bars.
 
teazer said:
Tune, that's a great tank and the single is amazing. Looks a little flexy around the swingarm pivot.

A new thin wall chrome moly frame would be the way to keep weight down. CB160 frame is much lighter than a 175, but make a replica to suit and save more weight. Check out a Laverda twin frame for a similar look but stiffer. That might be harder to scale down and replicate, but it's neater than a CB in many ways.

That Joe Biden ( load of Malarkey) frame is probably the stiffest and lightest ( and simplest) design, but hides the motor which is way too pretty to put behind bars.
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Teazer chrome moly was my first idea. Never worked with the stuff, or even welded it for that matter. I'd need to have a head stock made, no access to a lathe right now. I also need to make a frame jig if I go this route.
 
irk said:
Why not take one from a titled bike?
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That's what I meant in my earlier post, start with a donor titled head then go from there, saves a lot of headache in the registration process in most places.
 
I'm not sure that is the intent of the law, but it's the same frame - I just had to repair a few small parts. Honest....

It has been done I'm sure and to make things easy a single Ducati frame would be the way to go.

Chrome moly is as easy to weld as any other steel frame but don't cool it too fast after welding. In the UK they use SifBronze which melts at a lower temperature and causes less heat distortion and cracking, but harder to get here. My welding supply shop said they could get a 50 pound box for me for about 11 bucks a pound, but I couldn't use that in 10 lifetimes. it's RBCuZn-D sometimes known as nickle Silver because of the color. UTS is around 100,000 psi - as strong as the steel it is connecting. Eutectic #16 or Haris D rod would work. If you use TIG, you can just use normal ER70-S2.
 
teazer said:
I'm not sure that is the intent of the law, but it's the same frame - I just had to repair a few small parts. Honest....

It has been done I'm sure and to make things easy a single Ducati frame would be the way to go.

Chrome moly is as easy to weld as any other steel frame but don't cool it too fast after welding. In the UK they use SifBronze which melts at a lower temperature and causes less heat distortion and cracking, but harder to get here. My welding supply shop said they could get a 50 pound box for me for about 11 bucks a pound, but I couldn't use that in 10 lifetimes. it's RBCuZn-D sometimes known as nickle Silver because of the color. UTS is around 100,000 psi - as strong as the steel it is connecting. Eutectic #16 or Haris D rod would work. If you use TIG, you can just use normal ER70-S2.
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Wouldn't I need a head stock on the same metal?
 
Not necessarily. Chome moly is still steel and can be welded to regular steel without any issues as far as I know. The issue with welding thin wall tube to a steering head is that a steering head is thick and absorbs a lot of heat and while you are getting that hot enough, the thin wall tube has melted clean away. It takes practice to get the heat going in the right direction so to speak.

There are guys on here that are welders. Would be good to get some professional input.

Check out the Chop Shop for a jig, add 2x2 or 3x2 tubes and you have a jig. That's what I have but you can build one form scratch if you have the equipment and skills - I don't. :)
 
Hurco550 is an excellent welding instructor and a great resource. I'm surprised that dude hasn't jumped in yet.
 
teazer said:
Not necessarily. Chome moly is still steel and can be welded to regular steel without any issues as far as I know. The issue with welding thin wall tube to a steering head is that a steering head is thick and absorbs a lot of heat and while you are getting that hot enough, the thin wall tube has melted clean away. It takes practice to get the heat going in the right direction so to speak.

There are guys on here that are welders. Would be good to get some professional input.

Check out the Chop Shop for a jig, add 2x2 or 3x2 tubes and you have a jig. That's what I have but you can build one form scratch if you have the equipment and skills - I don't. :)
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I think people pre-heat the head stock but I am not sure, I am not a welder. But I have watched some of our fabricators at previous job weld very thick alloy to very thin and they pre-heated the thicker metal right before welding.
 
Correct. the larger/thicker part has to be heated first so that both parts are brought up to the same temperature at the weld point. Where the torch is pointed makes a huge difference as you weld. bias it towards the thicker part and watch what is going on with both parts as well as the weld.
 
teazer said:
Correct. the larger/thicker part has to be heated first so that both parts are brought up to the same temperature at the weld point. Where the torch is pointed makes a huge difference as you weld. bias it towards the thicker part and watch what is going on with both parts as well as the weld.
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On the cb450 headstock is wasn't bad at all, there's thin stuff already welded to it, and I started my weld there, aiming the torch towards the thick stuff, and by the time I got there is was nice and hot. I imagine with a similar headstock I could do the same thing.

I did not know you can weld a just "regular" steel to chrome moly. That makes things a crap load easier.
 
That motor would be great in a skyteam ace frame.
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If they can't be welded together I am in deep doo doo because I hit glued a few CroMo tubes to old steel frames and then stuck old steel brackets onto the CroMo tubes. I suspect that a whole new frame with consistent metallurgy would be better. Not hard to get a thick wall CroMo tube machined to make a headstock and go from there.
 
No issue welding Molly to Mild vs/vs just use mild rod or wire and prep good, preheat is good but no need in cherry red, just get the two good and saucy, you can see if your not getting penetration to the meaty side.

If mig I would avoid using a 110 welder tho, you want to turn it up and dig the wire into the headstock side just just enough so the pool is crumbing in the mild tube.
 
Oh and yeah... if you do use a torch and blow soot all over the cleaned weld zone, you do need to hit it with a wire brush or your favorite cordless with a wheel onit :eek:
 
all the above =preheat i would go 400 then weld then post heat wave a torch at it so the weld zone continues to spread some heat then cool slow by backing off the torch slowly or better yet wrap it in some insulation
 
collect a few more parts then it will be a lot of fun

check the motor over a lot of them had bottom end issues from over revving

here is mine last time i had it out





 
Thanks everyone for the input! I have a vague direction in my head now, but before all that will be tearing into the motor and seeing what's what. I want to juice a little more out of it, then bench test it once it's back together. Once it's good to go I will get the rest of a bike together.
 
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