'81 XJ650 Cafe Bobber thing

Hi,
I just got my bike back on the road. It's been a long long time since I rode a motorcycle, and I never actually rode this one before I tore it apart, but it seems to be running pretty well.
I got most of the major frame fab work done 5-6 years ago when I first picked the bike up ($550 CAD!), but got distracted by life for a few years. Got back on it a couple months ago and managed to get everything back together and mostly finished while there's still plenty of riding season.
I lurked and gathered a ton of info from this board, so I thought I'd better share what I squandered it all on.
I don't have many pics from along the way, but if you've got questions or anything let me k ow
Hope you dig it

*Oops. Won't let me post pics. There's probably a rule I'm breaking. Will return with pics once this is sorted...*

 

Hey awesome build man! I love the look of it! I just have a couple questions. What tank are you running? With air pods have you noticed any lack in power or carb not working right? What handle bars are you running and are those risersunder it?

 

can you post some photos of the seat and the mounting of the leaf spring , custom spring ?

 

Thanks Mikey,
Stock XJ 650 tank. Now has a small dent in the side because I'm an idiot. I'll either switch to an aftermarket tank or find one from an XJ750 for a little extra capacity.
Pods, as I'm sure you know, are....controversial. Haha
Right now, I've got a bit of a "meh" point around 4K-4.5k RPM, but it's fairly subtle so I'm not even sure how far out of the ordinary it is since I don't know what the bike felt like stock. I just set everything up again and resync'd.
Here's my ultra scientific high tech tuning technique (patent pending):If the bike is lean, it barks at me, if it's rich, it sounds like it's going to rattle apart. When it's running right it sounds like an angry sewing machine.
I used the dynojet kit since I couldn't order individual jets up here (Canada). I also replaced the rubber diaphragms as two of mine were torn.
Handlebars are regular drag bars. No risers, I've just got the fork tubes pushed up about 3/4" proud of the upper clamps to lower the front end a little bit more. Reasonable People will tell you you're not supposed to do shit like that, but then you're also not supposed to remove the rear suspension for no real decearnable reason either, and I didn't let that stop me. This is not the kind of bike ridden by a reasonable man.
Note: almost immediately after getting the bike on the road I realized the need for a front fork brace, so I have that on there now. If you rode the bike as pictured for any length of time, I suspect something bad would happen. Especially on the roads around Central Alberta.

 

Seat:
First thing I did was weld a bottom plate underneath the backbone tubes. You can see the plate in the first picture. It has two bolts sticking through the bottom of it.
Then I cut a piece that fits between the backbones and could sandwich the spring from the top. Drilled holes in the top plate, spring, and bottom plate. Bolted everything together, shimming to adjust the angle of the spring slighltly. Once everything was bolted up and aligned (ish), I welded the top plate to the back bones. In the second picture you'll see the end of the spring (cut to length during fitup), the top plate (with 2 bolts in it. I'm also using it as a ground so there's a wire atttached), and the spring.
I aligned the seat so that I could use the center hole (used to bolt the leaves together). I saved the factory rear tank mount and bolted it to the center spring hole. The tank does move up and down as the spring moves, but the movement at the front of the tank is mostly rotational. The spring never comes up, so the tank can't compress, and there is a crossbar under the spring to limit downward travel (so that I don't end up ball-riding a tire), so the spring can't go down anywhere near far enough to cause problems at the front of the tank.
I built a super shitty "I don't care anymore I just want to ride" bracket to mount the seat to the eye in the end of the spring. This hinges the seat at the rear, and the solo spring under the front provides a kind of "tweezer" action that seems to work pretty well actually.
The little chrome circles on the rear seat bracket are super bright LEDs for turn signals.
The spring is a standard 1-3/4" slipper/eye trailer spring from Princess Auto (Canadian equivalent to Harvor Freight). I think it was around a 26", 1500lbs but I can't really remember.
I will get a different spring in the future as I'd like to change the seating position and hinge location, but for now it's good enough.

I've only had a couple other people ride this bike, but both were impressed with how well my little contraption cushioned the ride. Especially considering that the seat is essentially unpaded.

Here's what is not awesome: there isn't really any spring dampening, so don't get cute on bumps or it'll try to buck you off.
Keep your ass on the seat. While it's tempting to stand while going over big bumps/tracks, if you take your ass right off the seat, it'll flick up when you hit bumps and gives a good hard slap right to the testicles (if equipped).
I could largely stop this by strapping the front solo spring to the leaf spring so the front couldn't flip up, but I consider it an unexpected quirk that adds to her character.

She's a weird, dumb bike and if you don't ride her right she'll punch you right in the dick.

opinions on the cowl fairing? I'm not sure what I think yet.

 

Looks like a hardtail version of what I'm building. I opted for a monoshock with a cantilever seat so I didn't have as bad as a ride. Looks good.


Here's mine.

 

Looks good man!
I'm working on an XS650 right now that I'm building a new softail rear frame and monoshock. I've raked the front end and done a partial single downtube. Still lots of work to do.


What shock are you using? How long is it eye to eye/end to end? Have you mounted the motor and checked the spring rate? I'm designing my rear frame now in CAD and I've been amazed how little information I can find on different shocks and spring rates for sportbike shocks and cheap aftermarket options.

 

I found a huge spread sheet somewhere, maybe chop cult or somewhere. Had eye to eye measurements along with dry weights of bikes. I went with a 2005 r1 shock. Yes, tested with engine in, just never rode. Drifted down a hill over a few 2x4s I had set up and it felt well enough. Most monoshocks have full adjustments for sag and rebounds and so forth, so I'll tune it a bit after everything is said and done. I want to say I'm some 10.5 inches on eye to eye. If I find the spreadsheet I'll let you know.

 

try here for monoshock info..

oldskoolsuzuki.info/wp-content/uploads/2015/07/shock_length_chart-1.xlsx

Obviously, geometry plays a big part, along with whether a shock uses dogbones or any other sort of mounting arrangements, but it for sure helps get you into the ball park.. After I narrowed my results down, i researched the bike they were on for setup and layouts.. Can't say I used CAD or anything, but well, I guess i dont have a legitimate excuse.

 

Man, that is a sexy and entirely crazy ride that scares the hell out of me. Awesome!

 

Thanks man, that's super helpful.
I'm mostly concerned with the overall length. I can tweak mounting angle a bit to fudge the spring rate to where I need it.
Good luck with the build!