carnaby_fudge
New member
i'm attempting to revive an old 1978 yamaha xs650. it's been sitting for a long time (not drained) and my dad told me the carbs may need replacing. so i've been researching replacement carbs if the originals can not be rebuilt. so here's the dilemma: the '78 had 38mm carbs which are darn near impossible to find. later model 34mm carbs are a bit easier to find and i've also found brand new 32mm carbs that are purpose built for the bike as an aftermarket part. my question is what will be the difference with the smaller carbs? i'm guessing a decrease in horsepower but does that come with an increase in mpg? anything else i should be aware of? thanks for your help.