Hey Bud, don't listen to those 670 guys, my little mach1 617 eats them up.
Hurle your carbs out to 44mm put bbo and bb5 needle jets, set needles to 3 and 4, 501 rotary valve, drill the back upper part of the box 1 1/2 inchon each side. Jet up about 6 sizes to start.
So many things can be done to these mighty 617's. just to name a few.
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