was a rupp roadster, now i dont know what to call it

XS750AU

Member
HURCO550 said:
Also dimpled the main frame. Looks good and adds rigidity. Win win


Sent from my SM-G920V using Tapatalk
Absolutely fantastic original work.
The biggest single improvement you could make for rigidity in the structure is to close in the side plates. By that I mean weld a continuous metal strip down the top of the frame bridging from side plate to side plate. You obviously have access to CAD/CAM facilities if you could get access to some CAE modelling it would confirm that a closed in box section is the most efficient section at resisting bending.
Keep up the great work.
 

Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
XS750AU said:
Absolutely fantastic original work.
The biggest single improvement you could make for rigidity in the structure is to close in the side plates. By that I mean weld a continuous metal strip down the top of the frame bridging from side plate to side plate. You obviously have access to CAD/CAM facilities if you could get access to some CAE modelling it would confirm that a closed in box section is the most efficient section at resisting bending.
Keep up the great work.
Thanks man! I have thought about something similar, but instead of full sheets, maybe some "x" braces in between the vertical ones. Just tacked up though this thing feels surprisingly rigid. I'll see how much more so once it's really welded up and I can do some redneck flex tests.

For now she is safe and sound in the living room. We'll see how well my wife likes motorcycle decoration when she gets home.



Sent from my SM-G920V using Tapatalk
 

Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
JSJamboree said:
So whats left of the rupp? The forks?
Ha, not even that. I'll have to look, I think maybe the wheel base and rake share dimensions

Sent from my SM-G920V using Tapatalk
 

TurdFurguson

Weird Indy Kid
DTT BOTM WINNER
Looked back and realized that the roadster wasn't like the blackwidow or scrambler, yeah thats totally different. There is alot of power left in that motor to free up, almost to much. Pull the governor, get a billet flywheel (the stock one will explode at high RPM), tighter springs, cone filter, exhaust, and throw a mikuni on there so its manageable. The stock carb turns into an on/off switch at this point and its almost unrideable. I need to get mine out of the shed
 

Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
JSJamboree said:
Looked back and realized that the roadster wasn't like the blackwidow or scrambler, yeah thats totally different. There is alot of power left in that motor to free up, almost to much. Pull the governor, get a billet flywheel (the stock one will explode at high RPM), tighter springs, cone filter, exhaust, and throw a mikuni on there so its manageable. The stock carb turns into an on/off switch at this point and its almost unrideable. I need to get mine out of the shed
funny man, what you just wrote is my exact plans for the motor, plus I'll probably do a billet con rod while I'm at it. For now it's just a cone filter, jetted carb and pipe... because money, or lack there of lol once I get it together and going ill piece the hop up stuff together as funds become available

Sent from my SM-G920V using Tapatalk
 

TurdFurguson

Weird Indy Kid
DTT BOTM WINNER
HURCO550 said:
funny man, what you just wrote is my exact plans for the motor, plus I'll probably do a billet con rod while I'm at it. For now it's just a cone filter, jetted carb and pipe... because money, or lack there of lol once I get it together and going ill piece the hop up stuff together as funds become available

Sent from my SM-G920V using Tapatalk
I cant say enough what a difference the mikuni made. Here is the kit that I put on mine.

http://www.ebay.com/itm/22MM-MIKUNI-CARB-KIT-PREDATOR-212-GX200-GX160-HONDA-CLONE-Drift-Trike-Mini-Bik-/252314674798?hash=item3abf20666e:g:10wAAOSwYlJW4GEm&vxp=mtr
 

Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
JSJamboree said:
I cant say enough what a difference the mikuni made. Here is the kit that I put on mine.

http://www.ebay.com/itm/22MM-MIKUNI-CARB-KIT-PREDATOR-212-GX200-GX160-HONDA-CLONE-Drift-Trike-Mini-Bik-/252314674798?hash=item3abf20666e:g:10wAAOSwYlJW4GEm&vxp=mtr
Yep, I have that saved on my watch list. I think iirc a Yamaha blaster carb is the same size mikuni, and van 2 be had for less coin yet

Sent from my SM-G920V using Tapatalk
 

XS750AU

Member
I have thought about something similar, but instead of full sheets, maybe some "x" braces in between the vertical ones.
Sorry for not getting back to you sooner. Refer to the attached photo, the top section (red line) is in compression, meaning it is being pushed from both ends. The current structure is not good in compression, much better in tension (being pulled at the ends). Cross braces also work well in tension but not compression, so I would suggest a solid sheet welded along the red line is the best option, but if you wanted to make some cool cut outs down the middle of the sheet then go up a thickness or 2! The current structure will behave a bit like a house of cards, once it goes it will go quickly.
The orange line is of secondary concern, and would just stiffen up the headstem, so you could cut a few seconds off your lap times ;D. That area is in tension so cross braces would be OK.
Hope this helps.
Love what you have done so far.
 

Attachments

Popeye SXM

Also used for MX
The current structure is not good in compression, much better in tension (being pulled at the ends). Cross braces also work well in tension but not compression, so I would suggest a solid sheet welded along the red line is the best option, but if you wanted to make some cool cut outs down the middle of the sheet then go up a thickness or 2! The current structure will behave a bit like a house of cards, once it goes it will go quickly.
The orange line is of secondary concern, and would just stiffen up the headstem, so you could cut a few seconds off your lap times ;D.

I love this project, but I agree, It could collapse, very quickly, say after a bump or two?
 

Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
XS750AU said:
Sorry for not getting back to you sooner. Refer to the attached photo, the top section (red line) is in compression, meaning it is being pushed from both ends. The current structure is not good in compression, much better in tension (being pulled at the ends). Cross braces also work well in tension but not compression, so I would suggest a solid sheet welded along the red line is the best option, but if you wanted to make some cool cut outs down the middle of the sheet then go up a thickness or 2! The current structure will behave a bit like a house of cards, once it goes it will go quickly.
The orange line is of secondary concern, and would just stiffen up the headstem, so you could cut a few seconds off your lap times ;D. That area is in tension so cross braces would be OK.
Hope this helps.
Love what you have done so far.
Popeye SXM said:
I love this project, but I agree, It could collapse, very quickly, say after a bump or two?
Thanks guys for the input! It really is appreciated. I am not, and do not claim to be an engineer, I'm just a welder that has access to 2d cad software and a waterjet ha. I plan to do a strip on the top and front as described, as well as one for good measure between the two bars of the "hardtail". They wont be just plain strips, they will have a few spots for flared holes as well as slots where I can weld them in to connect to the cross gussets. Even though I did a wood mockup a while back, there are still things that I would change now that I have this one made up and tacked together. But oh well, I will make this one work. Thanks again for the input, it didn't fall on deaf ears!

 

Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
The project isn't dead, I just got distracted by other things per the norm. My wife decided that it was time that the mini bike get moved out of the living room, so out to lift it goes. Working on mounting the rear brake caliper. I have a little bit of Lathe work to do, and the rest of the gussets for the frame should get cut on the waterjet tomorrow. More to come


Sent from my SM-G920V using Tapatalk
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
It's weird to lose our smart ass comments from a day ago. Now we have to come up with more smart ass comments.
 
Top Bottom