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Carburetor swap question

kentrx1

Member
I have a 1987 etlh 70 hp Yamaha that I got used and had sat for a long time. I have disassembled carbs, cleaned, ultrasonic cleaned, recleaned and still can not get mid level acceleration smooth. Cranks good, idles good, runs 3/4 throttle up good. Have a set of 1989 Yamaha carbs off 70 hp engine available. Carb body part numbers same except for jets. Is it worth’s try to swap?
 
Why not? Does not take much time to remove and replace the carburetors. Try it and see.

You be the source of good information for the next fellow.
 
My question is with it being different jet size would that be an issue? I wonder if there is some change between 1987 and 1989 that required a jet change.
 
My opinion is that the parts catalog is screwed up.

Both the 1987 and the 1989 70 two strokes use the exact same part number carburetors. If the part numbers of the carburetors are the same then the jets inside should be one and the same. If the jets inside are different then the carburetor part numbers should be different.

Assume two sets of carburetors. One from a 1987 model and the other from a 1989 model. Both having the same part numbers. Who is to know if the parts inside are different? The parts inside won't have part numbers on them.

But even if they are not, there should be no problem using 1989 carburetors on a 1987 motor. If the parts catalog is correct then that is exactly what Yamaha has done. if good enough for Yamaha then it should be good enough for a Yamaha owner.
 
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