Honda 75 - 90 carburetor

[rontbeamer]

My understanding is that the only difference between a 2002 Honda 75 and 90 is the carburetors. My question is does anybody know the difference between the the carbs? The parts breakdown looks identical. Is the difference just jetting or something else?

 

[MajBach]

Re: Honda 75 - 90 carburetor

asked and answered dozens of times. The bottom line is the cost to change a 75 into a 90 costs more then their difference brand new. it's also more than the carbs that are different, although i couldn't tell you what.

 

[rontbeamer]

Re: Honda 75 - 90 carburetor

The Honda mechanics on another board, say just the carbs are different on this motor, nothing else. The thing they don't know is what the difference is. Several people have asked and none of the Honda mechanics knew exactly what the differences in the carbs is, so I thought I would ask here. A different set of mechanics are floating around this board. Again,they (not one, but several) were very certain that carbs are the only difference between the two motors, unlike several other Honda's within a block size series. There seems to be some validation to this, because Honda prices a 90 carb at around $800.00. They should be a two hundred dollar part, if that much. The only reason to do that is to ensure that people are not upgrading 75s to 90s.

 

[MajBach]

Re: Honda 75 - 90 carburetor

Well, that makes sense. Would be interesting to see someone make the change and have it dyno'ed to see the results. Let me know.<br />Shouldn't a simple parts manual comparison yield the differences between the two?

 

[Silvertip]

Re: Honda 75 - 90 carburetor

To verify these engines are the same or not, have your parts guy check the part number of the complete cylinder head -- not just the bare head. If the numbers are different, its probably because the camshaft profiles are different. On four strokes, power is achieved through cam-compression-carburetion-exhaust tuning. You already know the carbs are different, and I suspect the cams, intake runners, and exhaust tuning are also different as may engine timing. Just a hunch on my part but my gut feel is you'll find at least two of the above are different making it impractical to do the swap.

 

[rontbeamer]

Re: Honda 75 - 90 carburetor

Good idea, thanks. I'll have my parts guy check the head and ignition part numbers. I'll also have him check the carb internal part numbers. The thing I really want to know is if it is just jetting or is the carb throat size different?

 

[Silvertip]

Re: Honda 75 - 90 carburetor

With the carbs, chances are the throttle bore is larger which means more air, which means larger intake runners etc.

 

[rontbeamer]

Re: Honda 75 - 90 carburetor

That's what I'm thinking, but nobody seems to know with certainty.