xj550 swingarm compatibility

Ok, I'm in the process of sourcing parts for my ambitious xj project and I need some information I can't seem to find in the forums. The closest I've came is chacal's writeup on engine swaps. I have an xj650 frame and scored a 550 engine for a steal. I'm trying to figure out if a 550 swingarm will fit on the 650 frame without machining it. Building on a budget, I don't want to buy a swingarm to find out it won't fit. If anybody knows or can get inside dimensions of where the 550 swingarm mounts, I would be eternally grateful!

 

Don't know if the 550 swingarm is a drop in swap, but your going to need that style swingarm. So you might as well get one and do the mods to make it work. I doubt if anything else will fit without mods, at least it would be setup for the motor.
BTW your going to need the rear wheel with the sprocket too if you don't already have them.

 

was honestly torn between the swingarm swap and fabbing up a hardtail rear section, so I was going to let this decide for me. If it's not a big difference in fitment, I'll still take the swingarm route. It would cost as much to either buy the dom or the swingarm. Ugh... Decisions decisions...

 

Also, the sprocket/cush setup wouldn't bolt up in place of the rear end? I figured Yamaha used the same wheel to cut costs, but wasn't sure.

 

I think the 550/sprocket wheel is different from the 650/shaft drive wheel, not entirely sure.

 

Ok, thanks. I'll do some more homework on that one. I would be willing to swap my whole rear drive setup for that of a 550, swingarm and all if anyone would be interested. Nice build btw, orange.

 

Thanks, tried to sell it. Might trike it out.

 

You can't just bolt a 550 swingarm into a "shaftie" frame. (Or much of anything '550' for that matter.)

The swingarm pivots on the shaft-driven bikes use large, semi-external ball bearings; the 550/Radian swingarm pivots on internal nylon bushings. The mounting dimensions and diameters, etc., are all completely different. It won't just "drop in."

There is little or no "interchangeability" between the drive train components on the shaft-driven bikes and the chain driven bikes. Rear wheels are completely different too.

If you're trying to drop a 550 motor into a "shaftie" frame, forget it. By the time you do all the necessary (drastic) mods you might as well get a 550/600/Radian frame. The motor mounts won't even be the same, the 550 crankcases were NOT "common" with the bigger bikes.

 

Beautiful. Thanks for the great info fitz! FWIW, the front bottom motor mount is pretty much spot on, not sure about the front mid mount, may have to make some adapter plates for that one. The rear mount, however is over an inch different. Looks like I'll be hardtailing this one then. I guess I should correct my swap ad to say I would swap the 650 rear setup for a 550 carb rack.

 

On the 550s, the rear motor mount is the beefiest and most important. The front mounts pretty much just keep the motor from dragging on the ground.

 

Good to know. I didn't want to skimp on the mounts anyway, and to be able to widen those up enough on the frame to accept this motor, I'm afraid there wouldn't be enough frame contact to weld the mounts back down on... Yet another reason hardtail would be a plus. I would take out the inward kick from the lower rails before the mounts to make them go straight back to the axle plates, allowing for a wider tire, and also giving me extra meat to attach my new mounts. It would also allow me to take out some factory offset of the rear wheel, better aligning it with the seat. Going to make an adapter to bolt up the rear sprocket and wheel, which not only saves me from trying to source a whole new wheel, but gives me freedom to align the sprockets.

 

LastReb...your orignal posting said you were wondering about being able to do this without machining, and that you are building on a budget.

That being the case, the simple, straight-forward answers are:

NO you can't do it without machining,

and

NO you can't do it on a budget.

Dave Fox

 

Well, I have access to welding equipment, machine shop equipment if I absolutely need it, and I have machine shop and fabrication experience, so the budget thing is doable. I'd rather not go milling the swingarm and fooling with bearings if I can help it, but the main thing is I wouldn't be able to sneak a swingarm into the shop at work very easily to mill it. Minus tires, I speculate I'll have about $500 in this build when it's done.

 

Hey Dave, pm me if you still have a 550 carb rack for sale, it's a long shot since it's been a while since we last spoke about it...

 

Help me understand this:

So the game plan is to take a 650 frame, then hardtail it and re-engineer it to fit a 550 motor that you don't even have carbs for yet (how about an exhaust system or wiring/TCI unit?)

And pull the whole project off for $500, plus tires. And be able to safely ride the finished product.

You're dreaming.

 

Close... $500 minus tires. It'll be close if I don't meet the budget goal. I have exhaust, am sourcing components for a multi spark cdi unit that I will be building in the coming months. Currently, all I need to have it running is the cdi, carbs, and possibly one coil (won't know til I can test them fully). I'd like to use stock carbs for ease of placement, but I'm not above building a single or dual carb manifold. The cdi will cost around $30 to build and be better than stock, btw. Right now, totals for raw metals look to be under $75. This is a mostly complete 650, so lots of little odds and ends are already there and can be modified to suit the build if need be. I think the amount of work I'll be doing myself is being underestimated. Fab work and other labor intensive items won't be factored into the dollar cost... Only parts I can't make (or would rather buy second hand to save hassle) will cost anything. Of course, raw material costs may go up, due to things unforeseen. I'm pretty sure if I can make a race engine with dual throttle bodies (with nothing but junkyard parts rebuilt by yours truly) for an old z car, I can build this bike on a dime. Like I said, I'm only about $70 in at present.

 

LastReb.......I don't have any more 550 parts available right now, sorry.

Dave F

 

No problem, thanks for the reply though!