ancient YZ overbore/crank balancing questions + 125/175 top swap

yzzz

Member
Mar 29, 2005
10
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i hav a 76 125 YZ C
it was the first year of the monoshock, air cooled
yamaha also made a 175 YZ that year only
same stroke, bored 10 mm larger
so i figured if i could get a 175 top end i'd be very pleased
but the cranks hav different part numbers
would this be cuz that much larger a piston requires crank counter weight differences?
or sum other reason ?
duz yamaha hav differing part numbers for exact same parts?

i hav never had a 2 stroke motor apart b4
the crank is counterbalanced (for piston weight)?
a lighter forged piston is not noticeable by itself?
or duz everyone get porting dun with an overbore, making piston weight diff. unpalpable ?
no crank re-balancing is needed wen overbored 2mm?

could i use an older CT-1or 2 175 enduro top end ???
or an IT 175 ???
and port it sum to make it more hp friendly?
or maybe that wouldn't even be necessary with an IT since if i port i'll go for more down low or midrange ?
since this motor is strictly top end power now (stock)
i dun race so i dun care about pipey powerband mods
 
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