advice on swapping carb parts from different year models?

XSiveAl

while trying to remedy a leaking carb bowl (stock '78E carb + stock 78E head) I discovered that the threads for one of the bowl screws had become stripped.. vibration, over torquing, ancient rotten aluninum.. who knows.. so i attempted to tap it out and replace it with a larger screw.. what a disaster.

after carefully enlarging the hole through the bowl and lining it all up square.. i cracked the bowl putting it back together. end of carb bowl.. with the hole enlarged in the carb body to match.. end of carb body.
Less dramtically I'll probably heli-coil it later and salvage it.

Question for the carb gurus...

I have '76C carbs that are nearly identical to the '78E carbs.. just a couple of slight differences.. improvements over the years no doubt.. EPA Sad

what i'd like to know: are there any physical differences in the internal passageways of the '76 carbs that would make it impossible to to just simply switch jets. slides and needles. by my comparison of year model charts and by looking 'em over i can't find any reason why it won't work.. i have new jets, floats and needle valves and i'd just got my mix right.

Lacking the wisdom of years experience i thought to ask though, is there a collection of info somewhere that outlines which year carb bodies will work on which year bikes.. and a comparison of stock specs.. suggested changes to tuning... anyone experiment with this?

very appreciative of your advice,
-XSiveAL

XSiveAl

nobody wants to touch this one, eh?.. don't blame ya

I put it together last weekend and it works just great,.. I used the 76 carb body and installed the 78E stock parts except the needle jets cause they were a slightly different construct with the o-rings a few mm off and the pilot screws cause they're dif too.... not sure if either will affect it's mix so much that i can't tune it.. but i didn't want to risk it. I haven't read my plugs yet but not only does it run really well.. but, i've got more pullin power and faster acceleration... with no smoking, no overheating, no flat spots and no stumbles in the transition from pilot to main. Super happy with the performance!!

I wonder how many of the different year carb parts are, despite differing parts #'s, totally interchangeable?

XSiveAL

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