XS400 Parts Interchangeability? Drum to Disc

So I bought a 1981 XS400 Special II as a project bike and am going to cafe it. It's in pretty decent shape and got it for $200. Major issue is that it has drum brakes front and rear and has wire wheels.

At a minimum I want to replace the front wheel/forks/brakes to upgrade from the drum to a disc. I'm assuming the '81 forks that can accommodate a disc setup are interchangeable and that the tree's are the same. If these assumptions are correct it shouldn't be to big of a deal to do the front. Anyone know if my front axle will work with the cast front wheels if i get the speed sensor to go with it?

I can't seem to find a good picture of the rear to see how the rear disc setup is configured. I've seen some weird looking parts on ebay that kinda of looks like some type caliper mount that bolts to the swing arm... Is that how it works or will i need to get a disc compatible swing arm? Which ones will work on my 81? If I decide to keep the rear drum, will the rear cast wheels that use a drum swap in for the wire wheels I have?

Kind of a side topic, thinking about doing a monoshock setup, but anyone have a source for calculating suspension geometry and spring rates for a monoshock setup? Can't seem to find anything besides people just saying to get a massive spring and if doesn't work, up the rate....

Thanks!

 

Was just checking out ebay... The XS400 came with a monoshock setup?

http://www.ebay.com/itm/1982-Yamaha-Max ... cc&vxp=mtr

Think that could be made to work on an 81?


Is there some type of spreadsheet or manual that has sizes and/or interchange information so I don't have to pester the forum every time I need info?

 

Here's the deal when it comes to the XS400s:

There were two distinct and different XS400s. The original was a twin-shock bike, with an SOHC motor with rocker-arm valve lifters with screw adjustment, similar to the XS650. These bikes were made up to and through the 1982 model year (which is the cause of the confusion.)

For '82 and '83, there was also a completely different XS400 sold. It came in both Seca and Maxim versions; and was a monoshock-framed bike with a DOHC, shim-over-bucket motor that is essentially "half an XJ."

With the exception of some "cycle parts" there is very little interchangeability between the two series. The aftermarket seems to only be aware of the earlier, twin-shock XS400s.

 

You need to get stuff from 2 bikes -
1978 XS500
http://www.bing.com/images/search?q=197 ... tedIndex=0
1978 SR500
http://www.bing.com/images/search?q=197 ... tedIndex=3

You may have to modify and improvise the parts to make them fit.
The front forks - dual brakes and rim from a XS750 might work.
http://www.bing.com/images/search?q=197 ... tedIndex=6

 

personally, I'd keep the wires and drums as it looks more period and in keeping with the look.