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Another 9.9 to 15 question, (sorry not again)

B

BRUPP79

Regular Contributor
Hello to all. First time poster, long time lurker. I am looking at doing a 15hp upgrade to my 1975 Johnson 9.9 short shaft. I have a few questions. First, I have been researching this awhile now, most parts I can find. The carb is looking to be difficult to find. I happen to have a second 9.9 carb. My thought was bore out the venturi to the 15hp size as I do a lot of custom machining on the side. From what I can find that is .875". The trouble is the out going side is .8125". Would anyone have the exact dimensions for the 15hp carb bore profile? Second question it this. I see that many change from the 9.9 exhaust tube to the 15hp tuner style. In doing my searching I found there was the cone style and a newer style that looks like the 9.9 model cut in half. Has anyone noticed a difference between the two? Thanks for the help. I tried to find more on this with the search, but I kept getting "sorry nothing found":(:(:confused::confused:. Brian
 
I have found the best is to find a used 15 hp carb, the exhaust tubes are not much of an issue unless they are restricted with carbon. You will of course report to us your results if successful with carb mods? Jet size will be adjusted, eh? If looking for 15 carb try Tim's Outboard in Hackensack MN @ 218 682 2331. Tell 'em Tim sent ya.
 
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Hey Tim, thanks for the reply. Yep, just found two carbs online. Just verifying that they are what I need. Also thanks for the phone number I will give a call. I see you are in Duluth, hope all is well. Weather has been nice up here, aside from a few sprinkles.
 
Yes a few storms but sure like the weather. Could be some stronger storms early tomorrow. I have a couple extra 15 horse carbs but just got 2 calls for 15 horse motors. Gonna have to convert a couple 9.9's myself now. Take care. Tim
 
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