Question about frame modification

T6h6o6r

XS650 Enthusiast
Messages
72
Reaction score
64
Points
18
Location
Oakland, CA
So I have a question regarding an idea I had for a brat-style frame modification... The first image is my rough attempt to replicate the Brat kit that I wanted to put on my bike, I'm sure most are familiar with the design...

IMG_20220826_195322.jpg


but seeing as it appears nobody sells/manufactures these kits anymore, and that I don't have any access to a tubing bender but AM a certified welder, I was wondering if y'all think it would be structurally sound if I were instead to fabricate a "box" so to speak, that matched the same contour, but was solid walled steel plate say 1/8 or 1/4 inch? That could also double as a place to hide the battery/electronics & wiring, maybe with some kind of hinged lid, or even just a flanged lip or something that I could then mount a solo seat on top of? It would have to also include the upper mounting points for the shocks, which is part of the reason Im asking for opinions because I imagine the load/stresses on those shock mounts to be substantial, and I don't want it to crumple or distort under my ass as I roll down the road lol... Anyways, this next pic is a VERY rough sketch just for a visual aid of what I'm imagining... bear with me, I cobbled it together using the apps available on my phone so it ain't pretty lol. Any input would be greatly appreciated
Picsart_22-08-26_20-03-52-678.jpg
 

gggGary

Just call me squirrel brain
Top Contributor
XS650.com Supporter
Messages
28,198
Reaction score
46,891
Points
813
Location
Baraboo, WI, USA
Spit balling, 3 sides and a lid should be fine with 1/8" the welded corners will contribute lots of stiffness.
fairly large openings cut in sides and top should be fine also.
 

Jim

Beyond the edge is the unknown. Here be Dragons
Top Contributor
XS650.com Supporter
Messages
13,358
Reaction score
51,229
Points
813
Location
Kansas City Mo.
You could make a box using 1/4" plate, but damn is that gonna be heavy.
You don't have a tube bender.... but you do have the rear hoop you're gonna cut off. It's pre-bent into the shape you're going for. Cut the rear hoop up and use it to "frame" the look you're going for (red), then box it in using thin sheet (yellow)



Untitled.png
 

jpdevol

Hacker of Frames,Wires and other things
Top Contributor
XS650.com Supporter
Messages
2,087
Reaction score
4,906
Points
263
Location
26187
Unless you wanted to use plate for the style, I think re-using the existing loop (Jim's suggestion) would be the easiest solution and save some fabrication to boot.

A couple of thoughts on lowering the rear loop as contemplated; 1) it moves the rear fuel tank mount, perhaps causing a std. tank to not fit, 2) you're also gonna need to fabricate a seat-pan and custom upholstery and 3) the upper shock mount is lower but also forward, perhaps different length shocks required. None of that is a big deal to overcome, but needs considered.

The existing rear loop, behind the shock mounts, doesn't really do much other than support the stock fender - it gets hacked off on many builds. A lot of the strength is in the tube from the rear of the cradle up to the shock mount saddles. When you chop that tube, use slugs to reattach the pieces. The rest of the forces on the rear loop are handled by the stock cross bracing.

Disclaimer: not an engineer, just a hacker of frames
 
Last edited:

T6h6o6r

XS650 Enthusiast
Messages
72
Reaction score
64
Points
18
Location
Oakland, CA
A couple of thoughts on lowering the rear loop as contemplated; 1) it moves the rear fuel tank mount, perhaps causing a std. tank to not fit, 2) you're also gonna need to fabricate a seat-pan and custom upholstery and 3) the upper shock mount is lower but also forward, perhaps different length shocks required. None of that is a big deal to overcome, but needs considered.
1) Yeah I am aware, I was planning to get an aftermarket tank that's a bit smaller than the stock, so this one won't be any issue.
2) I've already got a solo seat pan, and a friend who is an ace at upholstery, he makes custom messenger bags as a side hustle that are some of the coolest I've ever seen.
3) I have noticed this too, but it hasn't seemed to be a problem for tons of folks running those brat kits that essentially have the same altered geometry. I believe I read someplace that 10.5 or 11" shocks should fit the bill just fine.

Also, Jim, wow! And thank you. That is the kind of thing that only someone with experience in doing this kind of shit would notice. What a great idea and killer way to save $$ and reduce waste. To me that's what it's all about! I'm totally gonna try and make that work. That is the kind of eye/mindset I aspire to develop as I gain more experience and continue to build up my skills and knowledge.

Being able to post on this forum and learn from folks who know so much is so incredibly helpful! Many many thanks to all of you top dogs who are always there to offer guidance and pass along your knowledge to so many of us who would be lost without it. I can't even begin to say how stoked I am to have found this forum.
 

gggGary

Just call me squirrel brain
Top Contributor
XS650.com Supporter
Messages
28,198
Reaction score
46,891
Points
813
Location
Baraboo, WI, USA
@Travis
Opportunity is knocking...............
A member got all excited about making a ready to weld kit, then disappeared, normal.
:twocents: The curved top style instead of a point at the shock mount would be a hit.....
I'd be HAPPY to be a test mule on this. ;)
 

Travis

Staff Member
Top Contributor
XS650.com Supporter
Messages
4,451
Reaction score
1,212
Points
163
Location
Roberts, WI, USA
@Travis
Opportunity is knocking...............
A member got all excited about making a ready to weld kit, then disappeared, normal.
:twocents: The curved top style instead of a point at the shock mount would be a hit.....
I'd be HAPPY to be a test mule on this. ;)

I thought monstercraftsman said they were going to start making them again?
 

jpdevol

Hacker of Frames,Wires and other things
Top Contributor
XS650.com Supporter
Messages
2,087
Reaction score
4,906
Points
263
Location
26187
Taint the same - no curve..... I also like the double shear top shock mount better. Perhaps a cross-brace just ahead of shocks?

Set-up the bender Trav!
 

halfmile

XS Builder
Top Contributor
XS650.com Supporter
Messages
1,939
Reaction score
7,967
Points
513
Location
kansas
You could make a box using 1/4" plate, but damn is that gonna be heavy.
You don't have a tube bender.... but you do have the rear hoop you're gonna cut off. It's pre-bent into the shape you're going for. Cut the rear hoop up and use it to "frame" the look you're going for (red), then box it in using thin sheet (yellow)



View attachment 223125

When you make the battery box (yellow be sure to mock it up first with the motor in place and the carbs and air filters in place. Carb and filter`s can be a real problem so allow for them before you weld up the box. "don`t ask me how I know this":doh:
 

timbeck

HARDLY A GURU
Top Contributor
XS650.com Supporter
XS650.com Supporter
Messages
1,125
Reaction score
1,362
Points
163
Location
Boston,MA
For me the best Brat kit was from "Visual Impact" . Much better looking than the Monstercraftsman unit. '''

tim
 

T6h6o6r

XS650 Enthusiast
Messages
72
Reaction score
64
Points
18
Location
Oakland, CA
Yeah $299 for that monster craftsman unit seems pretty damn steep, I mean, can't you get a full hardtail kit for less than that?? Or am I tripping?
 

T6h6o6r

XS650 Enthusiast
Messages
72
Reaction score
64
Points
18
Location
Oakland, CA
And personally, although I have gone back n forth a few times, I think Ive settled on the idea that I prefer the look of the sharp pointy ones to the rounded ones. If I had the choice I'd go with the visual impact over monster craftsman. If anyone were to make one in that style I would buy one for sure!! (Hopefully for less than $300 but hey if that's really what you gotta charge to turn a profit well then it is what it is lol)
 
Top