The little Ducati Featherweight

bitchen find !
2 cents its got a lot less hp than a 160 twin, never will have as much hp if you go silly and try to grow it up i into a full size mc or even dress it up 175 twin frame with its heavy wheels,itwill be slower than stock, at everything it will be a real turd china scooters be smokin you on main street
someything like an sl125 would be the size frame and components to use
an xl250 mono frame is 3 times 2 big and heavy besides its a frame designed around long travel suspension tghe high steering neck is something to stay away from
an rd125 ? probably small and light enough
https://www.google.com/search?q=sl125&rlz=1C1FLDB_enUS562US569&espv=2&biw=424&bih=408&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiyvPyt3ffQAhVU4WMKHRO3CDwQsAQIGQ
 
xb33bsa said:
bitchen find !
2 cents its got a lot less hp than a 160 twin, never will have as much hp if you go silly and try to grow it up i into a full size mc or even dress it up 175 twin frame with its heavy wheels,itwill be slower than stock, at everything it will be a real turd china scooters be smokin you on main street
someything like an sl125 would be the size frame and components to use https://www.google.com/search?q=sl125&rlz=1C1FLDB_enUS562US569&espv=2&biw=424&bih=408&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiyvPyt3ffQAhVU4WMKHRO3CDwQsAQIGQ

I follow what your saying XB, but let's put numbers to it. The duke 160 from the factory was 235 dry. A 175 frame modified, with a 31mm front end, and stripped to hell and aluminium rims should be sub 200lbs. So as far as that plan goes I think weight will be manageable. Now for the old power. A 175 was advertised as 19hp, the 160 11hp. Yes, that's a big difference. I have a hard time seeing how 15-16 isn't possible without going nuts, and with improved compression the torque on the single should be better than the 175 twin no? And if I build a frame, I'm sure lighter would be possible.
 
good points ther frame is not that heavy and you have it and its titled but all the old jap street bikes have heavy heavy hubs an alloy rim wont do much its less than a pound
some 24 spoke wheels with tiny disc brakes fr/rear off an 85cc mxer would be tits and light lighter than the stock duc stuff
 
Just be aware that the CB175 had a claimed 20hp while the Duc 160 has a claimed "9.5"

Half the HP.

But the Cb175 has a dry weight of 320lbs where as the Duc 160 has a weight of 235lbs.

Most 125 trail bikes come in at 235lbs.

There are some numbers to help you decide.

Awesome project BTW. I would like to see a custom alloy frame!
 
CB160 supposedly made around 16 hp and in the real world that was around 11hp. 175 did not make a whole lot more.

250 duc in race trim and still reliable is about 31hp, so I think you should be able to warm it up a little and have a fun bike. BTW our 160 made over 20HP and it was fairly mild, so anything is possible..
 
Lots of good input!

XB, I don't disagree, perhaps a different wheel combo would be advised.

Brodie, right now it's all just "talk". Ideally I'd like to build a frame. That being said the 175 frame is right in front of me or I wouldn't even be talking about it. There's a good chance both may happen. Ride around with the 175 frame for a season while I take time and build a pretty frame.

Teazer, I'm glad to hear my original 16-18 hp isn't all that unrealistic for a streetable motor. With such low compression out of the box, and tiny carb for the size, i'd be willing to wager those changes married to the right exhaust and jetted right would make a noticeable difference. Out of curiously what did you do to your 160? Always good to see what those before you on the same motor did to find success. Or did you mean a honda 160?
 
I meant a Honda. Sorry. I should have made that clearer.

The 160 Duc was similar to the 200, 250 and so on, but I don't know what parts are swapable and what the limiting factors are. I like your plan of attack. Porting and other breathing improvements for more top end and raised compression to add more all the way through sounds like the right way to go.

Of course, the real plan will depend on what you find inside the motor - is there enough metal where you want to ports to go, for example and research into what works on those motors is always needed. That should keep you busy over the winter months.

And that Honda 175 frame can always have tubes replaced one at a time when no one is looking. ;-)
 
teazer said:
I meant a Honda. Sorry. I should have made that clearer.

The 160 Duc was similar to the 200, 250 and so on, but I don't know what parts are swapable and what the limiting factors are. I like your plan of attack. Porting and other breathing improvements for more top end and raised compression to add more all the way through sounds like the right way to go.

Of course, the real plan will depend on what you find inside the motor - is there enough metal where you want to ports to go, for example and research into what works on those motors is always needed. That should keep you busy over the winter months.

And that Honda 175 frame can always have tubes replaced one at a time when no one is looking. ;-)

Haha I could have the motor swap done in a weekend, would probably make any other changes then as well.

Even if say I don't port it immediately, just make the carb/exhaust changes, I'm sure there is improvement to be had, if only mild. I have to see what a piston will cost me. The down and dirty option is to mill the head, but I don't know enough about the motor to know what that will effect other than the obvious. I'd much rather get a nice custom piston though.
 
My little ace comes in at 190 lbs and 12.43 hp rw. What you are planning will be a joy to ride. Can you get a Honda cg 125 frame. Would be ideal


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orrible-64 said:
My little ace comes in at 190 lbs and 12.43 hp rw. What you are planning will be a joy to ride. Can you get a Honda cg 125 frame. Would be ideal


Sent from my iPhone using Tapatalk

Good to know!

Anyone know what's stopping me from using the 175 piston? Looks to have a higher crown, perhaps that and a little decking will provide the compression I want. Also the bore increase from 61mm to 62.5 will increase it.
 
Found someone with a 62mm 175 piston higher compression. Just trying to find out if I can make it work or not. I have a hard time thinking that I cant, it's only +1mm, and the crown is clearly higher, but I think should clear just fine.
 
Good luck finding one in the States, but an RD200 frame would fit the bill nicely me thinks. Relatively light, and it's a Yamaha part so that adds like... 5hp right off the line ;)
 

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VonYinzer said:
Good luck finding one in the States, but an RD200 frame would fit the bill nicely me thinks. Relatively light, and it's a Yamaha part so that adds like... 5hp right off the line ;)

Lol!!! Im sure there's an engineer somewhere out there laughing at me who could make a 3 pound frame out of chromoly with some crazy innovative design.
 
http://www.ebay.com/itm/1974-YAMAHA-RD125-FRAME-READY-TO-REGISTER-RD-125-OEM-/262745655428?hash=item3d2cdc8884:g:7-IAAOSwnHZYQf-i&vxp=mtr
 
VonYinzer said:
http://www.ebay.com/itm/1974-YAMAHA-RD125-FRAME-READY-TO-REGISTER-RD-125-OEM-/262745655428?hash=item3d2cdc8884:g:7-IAAOSwnHZYQf-i&vxp=mtr

That would be a super good start, use the head, back bone and down tube, cut off the rest... hell that center stand alone would anchor a tanker. The subframe tubes from the headstock could be modified where they intersect with the backbone to have some turned plugs with mount points for an aluminum subframe... add in or build a mono swingarm and you may be down as much as 50 percent of starting weight while keeping 100 percent of the rigidity :eek:
 
Tune-A-Fish© said:
That would be a super good start, use the head, back bone and down tube, cut off the rest... hell that center stand alone would anchor a tanker. The subframe tubes from the headstock could be modified where they intersect with the backbone to have some turned plugs with mount points for an aluminum subframe... add in or build a mono swingarm and you may be down as much as 50 percent of starting weight while keeping 100 percent of the rigidity :eek:

And theres the 3 pound frame! Haha seriously though that would be extremely light.
 
BarnBurner said:
I like the 175 frame but mostly because it's all ready to go!. Here's a Ducati 250 frame/swinger combo on eBay for cheap (http://www.ebay.com/itm/172444038172?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Also, it's my understanding the 160 is merely a bored out 125, which has different design than the typical 250/350 units. Maybe look and see if anyone races the 125s for some inspiration?

Well, thats my reason for liking the 175 as well. I have to pour a ton of money into another bike at present, so using what i have for now may have to do. Im not opposed to doing things twice so it may be a do it to ride, then go crazy with it at a later date. I feel fairly confident i could chop the cradle off the 175 frame and brace it out fine. The 160 motor was made to be a stressed member anyhow. And yes, the 160 is a bored 125, and the 175 250 350 and 450 are mostly unrelated. That being said. That 175 piston looks very close. If the piston doesnt pan out, i do the best bolt ons i can, hope for 13hp and keep cutting shit off the frame til im satisfied! I may have to use my legs as the swingarm and hold the rear wheel with my toes ;D

Obviously im not fucking with a 160 to go fast. I want extremely flickable and fun. Take it to the beach and what not.

So the motor will be here tuesday, and i may have time during the week to see how close it is to fitting in the 175 frame. I was looking at it last night, and i forgot how much time i put into the top triple clamp, an the lower stanchions, they really look mint.
 
Too many issues with using the 175 piston, will have to get exact pricing on having one made.
 
That's a shame that you can't modify a piston from a different Ducati single. What about any other 4 smokes from that sort of era with steep crown?
 
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