TBone, I know Dave and he can steer you straight. One of the riders he sponsors is Mark Mackay in Ohio, who is blazingly fast on the Elsinores (he has a half dozen of them). The portion of the frame that needs gusseting is the lower section, beneath the front of the engine where the frame tubes meet. Old issues of Dirt Bike had stories about doing this and it does need it. Welding the footpeg mounts is also good advice. I had one break coming off a jump, on one of those days I'd like to erase from my memory banks. I've heard about using later transmissions, but don't know the ins-and-outs. As long as yours is working, use it and replace it with something else when the time comes. And it will come, so start looking now. As for CDI ignitions, actually some Elsinores came with this stock. I've got PVL on my '74-1/2 Maico and recommend them highly, as do most vintage racers, so if they make one for your CR, get one. Points suck. I'd recommend buying from Dave at AMS. He's got the parts, the knowledge and he's a racers' racer.
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'81 490 Maico (King Kong!), 2000 CR250, 74-1/2 GP400 Maico, buncha street stuff