XS650 Cafe - Build #4

Thanks for the compliments, but it's not all great...lol

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.
 
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.

 
Making sure everything stays square while welding. A little heat can ruin all of your hard work during layout.


Damn glove caught on fire and ruined my rhythm!
 
Beautiful work! Glad to see you are continuing with the single shock. Nice work on the swingarm. Keep in mind that torsional stiffness about the pivot is the most important characteristic. A large diameter axle with high quality fixings to the arms helps tremendously, same principle as on the front. Staying tuned in.
 
jpmobius said:
Beautiful work! Glad to see you are continuing with the single shock. Nice work on the swingarm. Keep in mind that torsional stiffness about the pivot is the most important characteristic. A large diameter axle with high quality fixings to the arms helps tremendously, same principle as on the front. Staying tuned in.
Click to expand...

Thank you. I am aware of the extra strength needed at the swingarm pivot, the mono shock will add even more stress than dual shocks. For an axle I will be using a 12" x .75" extra high strength bolt that I ordered from Mc Master Carr. It is in the picture. I have plans to secure the pivot at multiple locations with .25" steel. The swingarm will pivot on nice needle roller bearings from Fastenal. I've got some ideas for strength that I took from Tony Foale's chassis design book. I hope it all works lol
 
Actually, I was referring to the swingarm itself - independent from the frame. Sounds like you have things pretty well thought through. Seems like I often see people underestimate both the importance of stabilizing a two shock arm, and severely failing to grasp the enormous changes to the entire chassis with any version of a single shock. Thought your lovely swingarm might benefit from a larger diameter axle as the physical size, or even spacers and associated component diameters is where all the stiffness value comes from (with regards to the axle). Had the notion that since you upsized the front bearings to accommodate the larger Suzuki axle you might reap the same benefit at the back. I realize keeping the Suzuki axle worked out to a straight forward way to mate up the parts, but Suzuki made that axle a lot larger for a really good reason!
No doubt getting the overall frame stiffness up to par with the new suspension will be the big challenge, but every bit helps! Keep up the great work!
 
jpmobius said:
Actually, I was referring to the swingarm itself - independent from the frame. Sounds like you have things pretty well thought through. Seems like I often see people underestimate both the importance of stabilizing a two shock arm, and severely failing to grasp the enormous changes to the entire chassis with any version of a single shock. Thought your lovely swingarm might benefit from a larger diameter axle as the physical size, or even spacers and associated component diameters is where all the stiffness value comes from (with regards to the axle). Had the notion that since you upsized the front bearings to accommodate the larger Suzuki axle you might reap the same benefit at the back. I realize keeping the Suzuki axle worked out to a straight forward way to mate up the parts, but Suzuki made that axle a lot larger for a really good reason!
No doubt getting the overall frame stiffness up to par with the new suspension will be the big challenge, but every bit helps! Keep up the great work!
Click to expand...


I see what you were saying now. I agree totally. I plan on using a harley rear wheel which takes a .75" axle. Along with the spacers etc., as you mentioned above, it should be plenty strong.

I am also considering adding additional bracing to the swingarm as well. I have been planning on using the gsxr shock and a linkage system, as that is how the shock was designed to be used. But, I am running into some fitment issues. I will do some more brainstorming, but I may have to go to the more common non-linkage approach with a different shock. In that case I will probably use a Ducati monster shock. They are good quality and designed to be used without linkage.

Thanks again!
 
Due to clearance issues I have to abandon my original mono shock linkage design. This adjustable Sachs shock from a Ducati is designed to work without linkage and should fit nicely.

 
For those wondering about my plans for mounting the swingarm, here it is.
This design ties the backbone, engine and swingarm together. The plates are cut from 1/4" steel. I still need to cut spacers for top mounting bolts.
There will also be additional support tabs on the frame tubes to help distribute the stress.













 
brad black said:
sorry, i mean where are the bearings or bushes? it looks like the frame and swingarm are both bolt sized.
Click to expand...

Oh, gotcha. Good eye actually. It looks that way because I have pieces of 1" tube acting as bushings between the swingarm and pivot bolt for mock up. Similar to a stock setup. The swingarm end tubes are 1" ID and the pivot bolt is 3/4".
 
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