CDI Box differences over the years ?

[randy]

But, it's already running!?

[dbeardslee]

Doesn't sound like it's running right, though . Maybe it's not an issue, but they're definitely different.

[oldnortonrider]

Somebody give me some input on this~~I'm almost sure that on the 81 engines that all start with "4R0" on the serial #, that there's not enough room to put the mechanical advance behind the timing plate. Mine is an 81, and PO had not only put a 2H7 CDI on it, but had changed the timing plate. The plate has "2H7...." stamped on the plate. Some time ago when I had discovered all this, if I remember correctly, I couldn't really see past the plate to tell if the mechanical advance had been stuck in there also. But at the time, I just assumed he had put that in there, too. Especially if he had gone to the extreme to change the timing plate. I'm thinking now that it ain't there. Because just recently I helped a fellow by email , that was having rev "flattening out" problems, that also had a 4R0 engine to discover that he had a 2H7 CDI; he STILL had the 4R0 timing plate, and said that there was no was NO way for a mechanical advance to be behind that plate. He said there was not space there for it. When the PO of my machine installed a 2H7 timing plate, obviously it was because that plate has adjustable timing slots~~where you can turn the plate. The 4R0 plate does NOT have these slots, unless one would be so inclined to cut 'em in there. The fellow XS rider that I was back and forth via email with for several weeks, DID go ahead and acquire a 4R0 CDI, and his revving problems are solved, to the best of my knowledge. I have not yet replaced the 2H7 CDI on mine yet, and installed a CORRECT "4R0" CDI, but that's definitely on my list to do. soon. As soon as I can attend to it, I'm going to pull the timing plate, and AGAIN inspect to try to tell if there's something behind the timing plate (without removing the plate) that could POSSIBLY be the mechanical advance. Again, as I had mentioned, the other fellow that I had helped with "4R0" engine, says: "can't be done".

(?)Anybody, on this.........(?)

[randy]

It can and has been done, cranks, crankcases and base plates are all the same, all years. the '81 and up models had special anti-tamper screws on the timing plate, but those can be drilled out. Some also had non-slotted base plates, but that's no biggie. The non-slotted base plate only prevents fooling with the static (idle) base timing. Other than those screws, there's nothing stopping swapping the rotors.