'79 xs650 Modern Cafe Build

[catskillmtncustoms]

I picked up this nice, low mileage xs650 special a little while ago to build into a modern style cafe racer. I have hundreds of ideas, but the main plan is: inverted forks, wide spoke wheels, custom made swingarm, new subframe, new rear frame section (down tubes cut below engine and build new from there back. I'm really looking forward to building this one!

 

[catskillmtncustoms]

I picked up a set of gsxr600 forks and started tearing into the bike to get a better look at the frame lines.

 

[Brassneck]

Awesome! Looking forward to seeing it come back to life!

 

[catskillmtncustoms]

I picked up some nice wide 18" front and rear spoke Harley wheels on the cheap. Unfortunately, the front hub just wasn't going to work out, even after some machining. I'll shelf it for another build.

So, I picked up a sohc cb750 front hub as I could get bearing to fit the hub bore and the 25mm gsxr axle. I just had to make a center bearing spacer and the hub fits right on. I'll machine some aluminum outer spacers to center the wheel once the hub is courted and the bearings are in for good.

 

[catskillmtncustoms]

I ordered up some stock to get started on the frame and swingarm fabrication. The stock frame down tubes are thin walled 1 1/8" tube (.083 wall?), but I am going to use a 1" .120 wall DOM tube. The 1" .120 wall will not only be plenty strong, but will use .75" tube for joint slugs. I will just turn down custom slugs to reenforce the connections to the stock down tubes. The new frame work will give a clean look, eliminate the ugly area where the swingarm and pegs mount and make room for a mono-shock set up.
The swingarm will be made from 1x2" .120 wall rectangle tube, use needle bearings and a 3/4" pivot axle.

 

[fredintoon]

Hi catskill,
great to see an XS650 upgrade plan that don't involve the designer lurching back to the 1930s waving a sawzall.

 

[Yamaha_chop]

Inverted forks, mono shock? You know that's my style!

Can't wait to see it come together!

 

[catskillmtncustoms]

Hi catskill,
great to see an XS650 upgrade plan that don't involve the designer lurching back to the 1930s waving a sawzall.

Inverted forks, mono shock? You know that's my style!

Can't wait to see it come together!

Thanks guys.
I don't only want to install the modern suspension components, but I want to do it correctly. I didn't mention it above, but my reason for fabricating a new swingarm is to run the wider wheel/mono-shock while keeping the correct wheel base. I could easily stretch and modify the stock swingarm, but that would create a longer wheel base and affect handling.
I will also keep an eye on things up front. Once the steering bearings are in I'll have to take measurements for rake/trail. If need be I'll modify the neck to get the correct geometry.

 

[TwoManyXS1Bs]

Just a thought. Could run this by Tim of DO THE TON. Some members have stiffened the swingarm area with a little cross-bracing...

 

[catskillmtncustoms]

Just a thought. Could run this by Tim of DO THE TON. Some members have stiffened the swingarm area with a little cross-bracing...

View attachment 49621

Thanks, I've seen that. But I'm planning on cutting out that entire area and re-building it. I have some similar ideas to brace the swingarm pivot against the backbone.

 

[Yamaha_chop]

Sorry I misread that last part.

What sort of rake # are you looking for?

Also keep an eye on how much wider you go with the rear wheel. Chain alignment can be tricky and a custom offset sprocket gets pretty spendy. I had one made for my build with a 240 tire but it wasn't cheap.

 

[fredintoon]

- - - Also keep an eye on how much wider you go with the rear wheel. Chain alignment can be tricky and a custom offset sprocket gets pretty spendy. I had one made for my build with a 240 tire but it wasn't cheap.

Yeah,
anything wider than a 130 does nothing to enhance the handling, it's a mere fashion statement.

 

[catskillmtncustoms]

Yeah,

anything wider than a 130 does nothing to enhance the handling, it's a mere a fashion statement.

Your absolutely right. I'm not looking to go very wide, 140-160 range. The bigger issue is with the diameter. I am planning on 18" wheels front and rear. The 18" rear wheel I'm using for mock up rubs the tire up near the front of the swingarm because of the straight taper design of the swingarm. My swingarm will be stock length/width at the rear, but have more room up front. A basic flattrack swingarm style.
In the end the little bit of extra tire width is for style. Technically the extra weight is a downgrade, but I don't think it will be noticeable with the sizes I'm looking at. On my last build I stayed narrow to keep things function-first, but I really think wider tires would have looked great...

 

[catskillmtncustoms]

Yeah,

anything wider than a 130 does nothing to enhance the handling, it's a mere a fashion statement.

Your absolutely right. I'm not looking to go very wide, 140-160 range. The bigger issue is with the diameter. I am planning on 18" wheels front and rear. The 18" rear wheel I'm using for mock up rubs the tire up near the front of the swingarm because of the straight taper design of the swingarm. My swingarm will be stock length/width at the rear, but have more room up front. A basic flattrack swingarm style.
In the end the little bit of extra tire width is for style. Technically the extra weight is a downgrade, but I don't think it will be noticeable with the sizes I'm looking at. On my last build I stayed narrow to keep things function-first, but I really think wider tires would have looked great...

 

[gggGary]

Nice project, I'm watching. Yes it's odd how fashion affects our eye, a skinny rear tire just LOOKS skinny with all the fat tires we are used to seeing now.

 

[racerdave]

Nice project to follow. Is that a BB Chebby motor holding the floor down?

 

[catskillmtncustoms]

Nice project to follow. Is that a BB Chebby motor holding the floor down?

Good eye. It's a 396 from my SS Chevelle project.

 

[catskillmtncustoms]

I managed to shave some weight off the xs....

 

[catskillmtncustoms]

The xs used 1 1/8" .083 wall tubing for the dowm tubes, and 7/8' .083 for the subframe. I'm going to use 1" .120 wall for everything, so I turned down some quick frame slugs to match.

 

[fredintoon]

The xs used 1 1/8" .083 wall tubing for the dowm tubes, and 7/8' .083 for the subframe. I'm going to use 1" .120 wall for everything, so I turned down some quick frame slugs to match.

Best step-bore those slugs out to .120" wall too.
They'll weld up nicer and every ounce counts, eh?