Are the diameters and specs the same between the weights and rollers for the BW and CA spider part in the clutch. I don't want to order something that won't work
Yamaha used 2 different roller pin (axle) diameters for these clutches, and thus 2 different roller bushing ID's. I've never directly compared the 8BW & 8CA spiders to each other, but:
The 8BW spider likely has the smaller version, 8mm dia.
The 8CA spider likely has the larger version, 9mm dia.
Do you have a way to accurately measure your pin OD in a location where hasn't worn at all? You may be able to reuse your pin if it does not show any measurable wear where the roller rides (measure with micrometer or caliper), it is usually the roller bushing that takes the brunt of the wear.
The 8BW spider dates back to the 1994 Vmax 500-600-750 product lines, and it just so happens that 8BW is the prefix of the 1994 Vmax4 snowmobile model number. This spider was used well into the 2000's, just not on all of the sleds that used this type of clutch.
What you can do for your new rollers is to find the 98 Vmax 600SX roller OD spec, and order new rollers with that OD and in the pin size you just measured above (likely 8mm). If you need pins, order those to match as well. Here are 2 pages to help:
http://www.totallyamaha.com/snowmobiles/AAATuning Chart/Specs.htm
http://www.totallyamaha.com/snowmobiles/aaTECH/drivespecs/Rivets_Rollers.htm
Weights all take the same pin diameter, and are thus interchangeable over a very wide range of years and updates of these clutches, from the early 90's well into the 2000's. Source the weights and rivets for your model and you'll be well on your way, you may want to pick up a new spring as well, especially if yours is not the same color code as spec for your sled. And a new Yamaha belt if yours is worn.
Also note that Yamaha has 2 different spring lengths for this style clutch, and these correspond with the cap/cover style, either SHORT or TALL. Your sled would have a short cover originally, and likely still does based on the spider application, unless the cover has been changed (the covers do interchange in combination with the proper spring). Post up a pic of your cover if the style is in question.
http://www.totallyamaha.com/snowmobiles/aaTECH/drivespecs/primary_springs.htm
As long as your clutch is sound, with no cracks or damage, there is no reason you can't use it by giving it a good cleaning, inspection, and replacing any worn out moving parts. Clean it (and the secondary) in the dishwasher or in a bath of solvent/mineral spirits, check & clean all the nooks and crannies especially where bushings and moving parts are located. Make sure the plastic slider bushings inside the towers are not too worn or cracked, slide the moveable sheave up and down and rock it back and forth. It should slide smoothly without hangups or drag, and with it's age it will likely rock a little but you don't want it sloppy like the center bushing is worn out or missing. Put the spring cap/cover back on without the spring and do the same checks as above, it should still slide smoothly but the rocking should be noticeably reduced, if it is sloppy at all you need to look closely at all of the bushings.
Lastly, use only Yamaha replacement parts even if they cost more, the aftermarket stuff is low quality and you will regret using it, clutching is not a good place to try to save a few bucks on inferior components.