catskillmtncustoms
XS650 Addict
I was actually planning on that, but ran out of time today. Mostly for the welding benefit. But, the weight shave is always a good bonus.
Last edited:
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'79 xs650 Modern Cafe Build
- Thread starter catskillmtncustoms
- Start date
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- Tags
- cafe custom fabricating
I was actually planning on that, but ran out of time today. Mostly for the welding benefit. But, the weight shave is always a good bonus.
catskillmtncustoms
XS650 Addict
I found some time to get in the shop today. I step bored the frame slugs, for the reasons mentioned above. And, I got started on a frame jig to keep everything nice and straight.
Yeah, straight is a good thing!
Got me a plunger-frame A10 a half-century ago and found too late the bargain price was because it's frame was bent.
Fixed that by hanging a sidecar on it so the bike's tendency to turn one way was balanced by the sidecar's tendency to turn it the other.
Mind you, that fix ain't for everybody, eh?
Got me a plunger-frame A10 a half-century ago and found too late the bargain price was because it's frame was bent.
Fixed that by hanging a sidecar on it so the bike's tendency to turn one way was balanced by the sidecar's tendency to turn it the other.
Mind you, that fix ain't for everybody, eh?
catskillmtncustoms
XS650 Addict
I found a little time to get into the garage today. I managed to get the frame jig just about finished, and I turned down an aluminum cone for mounting the neck tube to the jig.
catskillmtncustoms
XS650 Addict
Another small update, the holidays really slowed things down for a bit. But, I've been making some progress.
The neck cones are done, and the frame jig is almost ready to rock. I just need to install the leveling bolts and clamps for the down tubes.
I got the frame de-tabbed, degreased and prepped for welding.
Got my rear shock.
And I'm just waiting in some back ordered dies...
The neck cones are done, and the frame jig is almost ready to rock. I just need to install the leveling bolts and clamps for the down tubes.
I got the frame de-tabbed, degreased and prepped for welding.
Got my rear shock.
And I'm just waiting in some back ordered dies...
catskillmtncustoms
XS650 Addict
The frame is secured in the jig. Everything level, square and the neck set at the stock 27 degrees.
catskillmtncustoms
XS650 Addict
No physical progress lately, but I've been working on some geometry. After doing some drawings I am now debating the monoshock...
Here is a drawing of the stock geometry, but with the gsxr forks and 18" wheels front and rear. The swingarm pivot is at the stock location. As you can see this creates a low trail number.
The measurements are converted to inches:
So, I have a few options to look at. The solution will likely be a combination of below:
1. Decrease the swingarm angle.
2. Wheel sizes-taller front/smaller rear.
3. Raise swingarm pivot.
4. Extend forks (I don't really want to do this...)
The reason for possibly ditching the monoshock is swingarm angle. With dual shocks I can have multiple mounting holes on the swingarm for easy adjustment like you will notice on flattrack bikes. This is hard to do with a monoshock. Also monoshocks from modern bikes are pretty long. I don't know if I can fit the shock, and maintain good swingarm angle without extending the wheelbase. I am shooting for around a 54" wheelbase with the wheel all the way forward.
I think I will begin by looking at raising the swingarm pivot just a bit, so I can keep about a 10 degree swingarm angle. Hopefully pairing that with a 19" front wheel will get me a bit closer.
I'll post some more as I work thru these issues. I have limited geometry knowledge, so input from anyone with more experience would be great.
Here is a drawing of the stock geometry, but with the gsxr forks and 18" wheels front and rear. The swingarm pivot is at the stock location. As you can see this creates a low trail number.
The measurements are converted to inches:
So, I have a few options to look at. The solution will likely be a combination of below:
1. Decrease the swingarm angle.
2. Wheel sizes-taller front/smaller rear.
3. Raise swingarm pivot.
4. Extend forks (I don't really want to do this...)
The reason for possibly ditching the monoshock is swingarm angle. With dual shocks I can have multiple mounting holes on the swingarm for easy adjustment like you will notice on flattrack bikes. This is hard to do with a monoshock. Also monoshocks from modern bikes are pretty long. I don't know if I can fit the shock, and maintain good swingarm angle without extending the wheelbase. I am shooting for around a 54" wheelbase with the wheel all the way forward.
I think I will begin by looking at raising the swingarm pivot just a bit, so I can keep about a 10 degree swingarm angle. Hopefully pairing that with a 19" front wheel will get me a bit closer.
I'll post some more as I work thru these issues. I have limited geometry knowledge, so input from anyone with more experience would be great.
catskillmtncustoms
XS650 Addict
Already found some flaws in my numbers above...
Yamaha_chop
Fabricator Extraordinare
On my last two builds I've used a shock from a Buell 1125r. There are some good benefits to this shock.
1.they can be had very cheap from ebay
2. They are quite short in overall length
3. Most important to me, they are designed to be direct link, no linkages or dogbones.
1.they can be had very cheap from ebay
2. They are quite short in overall length
3. Most important to me, they are designed to be direct link, no linkages or dogbones.
catskillmtncustoms
XS650 Addict
Much better now.
catskillmtncustoms
XS650 Addict
Cat's skill That's some cool math/diagram there, is that drawing based on a template with formulas built in or did you do it from scratch?
catskillmtncustoms
XS650 Addict
catskillmtncustoms
XS650 Addict
Getting some work done today.
nicmcs
XS650 Enthusiast
Liking the progress, will keep watching.
also I love the tidy little workshop.
also I love the tidy little workshop.
catskillmtncustoms
XS650 Addict
Now that I finally have a solid design I started work on the frame. This is just a start, the backbone will be getting some attention as well.
I bent up matching tubes, and slowly hand cut the notches for a tight fit. You can also see the frame slugs in the first picture.
Mostly welded. I'll have a lot of finish welding once the frame is out of the jig.
Taking shape.
I bent up matching tubes, and slowly hand cut the notches for a tight fit. You can also see the frame slugs in the first picture.
Mostly welded. I'll have a lot of finish welding once the frame is out of the jig.
Taking shape.
catskillmtncustoms
XS650 Addict
Very good looking work.
Thinking about what I see and just trying to be helpful.
Might want to check that the engine mounts will line up, from watching other major projects, the frame tends to spring when cut that way...
Maybe you have it confirmed already, the drive chain path and that new lower left curved tube, is there good clearance?
Thinking about what I see and just trying to be helpful.
Might want to check that the engine mounts will line up, from watching other major projects, the frame tends to spring when cut that way...
Maybe you have it confirmed already, the drive chain path and that new lower left curved tube, is there good clearance?
catskillmtncustoms
XS650 Addict
Good eye.
I didn't want to place the engine in the cut frame and risk bending it out of square. So, I had to rely on measurements for the chain clearance/motor mounts, and wait to confirm once I could place the engine back into the frame. After placing the motor back in the frame there is good news and bad... The good is that the motor bolts right in, everything lines up perfect. The bad news is that the chain clearance is tight, too tight.
It sucks, but it won't be too bad to fix...you always have to expect some setbacks.
catskillmtncustoms
XS650 Addict
Sorry for another slow update. I've actually been taking some of these cold days to stay in the house and expand my knowledge a bit. I'm currently working my way through Paul Thede's Race Tech Suspension Bible, and Tony Foale's Motorcycle Handling and Chassis Design. Great books, but I will definitely have to re-read almost every chapter because there is a lot of info to take in.
But, I have made some progress in the workshop. After my last post/mistake I had to go and cut out the tube work and start over. This new frame design is actually my first design, but I thought the other layout would be a cleaner look. I came up with this solution after looking at flattrack frames from companies like Cheney and Frame Crafters.
The frame still needs a lot of work. I am considering cutting the downtube and re-making the motor mounts, and I will eventually add bracing at the bottom to tie everything together.
Before I can finish up the frame I need to finalize my monoshock plans. It will be hard to describe what I have in mind without pictures, so for now I will just say that I'm planning to use a linkage system. I got started on my swingarm so I can move forward.
Just a nice winter day in the workshop.
But, I have made some progress in the workshop. After my last post/mistake I had to go and cut out the tube work and start over. This new frame design is actually my first design, but I thought the other layout would be a cleaner look. I came up with this solution after looking at flattrack frames from companies like Cheney and Frame Crafters.
The frame still needs a lot of work. I am considering cutting the downtube and re-making the motor mounts, and I will eventually add bracing at the bottom to tie everything together.
Before I can finish up the frame I need to finalize my monoshock plans. It will be hard to describe what I have in mind without pictures, so for now I will just say that I'm planning to use a linkage system. I got started on my swingarm so I can move forward.
Just a nice winter day in the workshop.
