Swingarm Dimensions

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Msimz

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Hi All,
Hoping someone is willing to help out here. I’m doing a 1979 XS1100 build, and looking for a better swingarm option (mostly to accommodate better rim / tire combos). Early VMax looks like a promising option. Was hoping someone would measure the width of their swingarm where it mounts to the frame. Trying to see how extensive the mod would be. Thanks in advance!
Mike
 

one2dmax

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If I recall correctly you can use an XJR arm with some mods? Can't remember for sure but have a local friend that has done a lot of work to his XS11.
 

Msimz

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Thanks Sean, I'll look into it. I've heard FJR rears would technically work, maybe a driveshaft extension needed.
Mike
 

Shaarth

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I’m Sean Morley’s local friend. This is my first time on reply. Hope I don’t mess it up to bad. Here are some picks of my 1980 xs1100. It has an XJR fuel tank and a 2004 Vmax front forks. Including speedometer and Kosovo fuel gage and tachometer. The drive shaft on the FJR 1300 is 1” wider. If you move the swing arm to align withe the drive shaft your rear wheel will be offset to much, and will not handle well. I moved the xs1100 shaft out 1” by expanding the middle gear box and lengthening the shaft. See thumbnail. The fjr drive shaft should fit. Aprox 3” longer swing arm. Everything is prepared to be fitted and welded. Just don’t have the time. If had to do over I would of went to a chain. There is a chain conversion would be a lot cheaper an easier. Hope this info helps you with your project.
 

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Fire-medic

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One of the guys I know here has a turbocharged XS-11. He was a Snap-On dealer for many years. His bike was always immaculate.

Sounds like you have received some good advice.
 

Shaarth

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Sean Morley has been a very good influence. I have to give him a well deserved pat on the back.
 

Msimz

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I’m Sean Morley’s local friend. This is my first time on reply. Hope I don’t mess it up to bad. Here are some picks of my 1980 xs1100. It has an XJR fuel tank and a 2004 Vmax front forks. Including speedometer and Kosovo fuel gage and tachometer. The drive shaft on the FJR 1300 is 1” wider. If you move the swing arm to align withe the drive shaft your rear wheel will be offset to much, and will not handle well. I moved the xs1100 shaft out 1” by expanding the middle gear box and lengthening the shaft. See thumbnail. The fjr drive shaft should fit. Aprox 3” longer swing arm. Everything is prepared to be fitted and welded. Just don’t have the time. If had to do over I would of went to a chain. There is a chain conversion would be a lot cheaper an easier. Hope this info helps you with your project.

Thank you for that, super helpful! I love the shaft drive, and I’m having a hard time weighing the negative of a chain drive (a “negative” for me, not to say it isn’t superior in many ways) vs the positives of the much better looking (for my build) mono swing arm, which would probably also be a bit lighter (just a guess) and would allow for much wider rear tires.
 

Shaarth

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If you build mono swing arm. The frame is not designed for one. You will have to weld gussets to strengthen the frame. A single sided shock like the BMW K1100rs would be much simpler. And still be able to move the right side exhaust pipe closer to the frame. Like many modern swing arms FJR1300 swing arm is very strong and light and will easily handle the stress. Also the rear master cylinder will get in the way of the wider swing arm and will have to be moved to the outside the frame. See one of my picks. I also have designs to change cable clutch to a hydraulic clutch and some pics of completed chain and shaft drive xs1100’s. If your interested I will dig them out. Hope this helps.
 

Msimz

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If you build mono swing arm. The frame is not designed for one. You will have to weld gussets to strengthen the frame. A single sided shock like the BMW K1100rs would be much simpler. And still be able to move the right side exhaust pipe closer to the frame. Like many modern swing arms FJR1300 swing arm is very strong and light and will easily handle the stress. Also the rear master cylinder will get in the way of the wider swing arm and will have to be moved to the outside the frame. See one of my picks. I also have designs to change cable clutch to a hydraulic clutch and some pics of completed chain and shaft drive xs1100’s. If your interested I will dig them out. Hope this helps.
Thanks man, I'll take whatever pics you've got!
As for the gussets - I plan on chopping off the rear subframe anyway. My goal with the rear of the bike is to clean up that whole area. Hence why I don't love the factory shock mounting locations, it just looks too crowded and busy. I'm not afraid of the fab work - I own a few CNC machines for my day job (cabinet maker / woodworker) so I have an okay working relationship with several CADCAM options. Plan is to cut the rear subframe out, draw up some nice seat brackets and have a local guy laser them out for me with 1/4" steel or the like. I can add bracing wherever necessary. The new seat bracketing parts can also provide a new landing spot for upper suspension mounts.
Another goal, besides the aesthetics, is to hopefully be able to use a wider rear tire. However, I'm starting to think that just using the notch method on the factory shaft tube I maybe can squeak in a 140? Would rather a 180, but I think I could be happy with the 140 since I only really plan on this being a buzz around town kind of bike anyway.
In your opinion, do you think I could modify an R1 wheel to take the shaft drive? I have a machinist next door.
If I could get a bit of a wider tire on there, I'd keep the stock wheel. Then I'd be tempted to try to figure a way to keep two shocks, but to move the mounting locations to reduce the angle of the shocks so they don't attach up near the seat, but rather lower somewhere on the main frame. Again, I'd brace as necessary.
This guy on customfighters used his factory swingarm and it looks pretty good - won't let me DL the pics but here is the link - about 2/3 of the way down the first page:
xs1100 Fighter | Custom Fighters - Custom Streetfighter Motorcycle Forum
Sorry for the mental diarrhea.
Mike
 

one2dmax

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We did help Dale with making the spacer and shaft extender. We can probably make another if needed.
 

Shaarth

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Now that the program for the spacer and shaft extender has been done, it should be a little cheaper. Notching the swing arm should work. The xs1100 swing arm is very similar to the Vmax. Sean’s has notched lots of swing arms. He could help. I think the rear wheel rim is just to narrow. And is a solid aluminum. Very heavy. The biggest weight savings on the rear is the rim. A wider hollow rim would save a lot of weight. As far as an R1 rim. Anything is possible if you have enough time and money. I would ask Sean Morley. He’s adapted anther rims to vmax’s. But the stock swing arm is just to narrow to benefit a wider rim. A notched swing arm would easier and cheaper. And would save a lot of time and money.
 

Msimz

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We did help Dale with making the spacer and shaft extender. We can probably make another if needed.
Thanks Sean! So the spacer and shaft extender were to put an FJR 1300 swing arm and drive shaft onto an XS1100? Does this allow for the proper center alignment of the rim using that combo, or is there additional fabrication / math to get the centerline aligned properly? Thanks again.
Mike
 

Shaarth

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I’ve been putting it off. It’s a good time for me to assemble everything and make sure everything fits. And get it all welded up. Then send you some pics. I found the write up on converting to a hydraulic clutch. There’s several pages. Probably better to send it to you E Mail.
 

Msimz

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I’ve been putting it off. It’s a good time for me to assemble everything and make sure everything fits. And get it all welded up. Then send you some pics. I found the write up on converting to a hydraulic clutch. There’s several pages. Probably better to send it to you E Mail.

Amen man. Would love to see assembly pics / progress. I have seen the write up on the clutch. May happen down the road, admittedly not super high on the priority list atm.
 

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