yeah unfortunately bike engines on a kart don't make much sense most of the time
The D106 prefix on the engine code suggest a 82cc engine,
IDK about exact bore and stroke 48 x 45 or such I think..
Anywhoo.. you'd need to find a kartengine with similar specs then you might
be able to reuse the expansion chamber (just need to adapt flanges)
the comer SW80 is no match I'm afraid (50some bore 36some stroke)
I think you'll have to make your own for both in the end...
'sid