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Joe WOT Operating Range for OMC 15 HP motor

jdkline

Regular Contributor
" Hey, how are you? Was wonde

" Hey, how are you? Was wondering if you knew if the recommended rpms at WOT were 6000-6500, or is it 6000-7000? Thanks a lot. Also, you were talking about that you had some OMC parts left? Do you have a carb rebuild kit for the 15? I need to replace the bowl gasket. It sometimes leaks, so I'm afraid I'm going to blow myself up. If you have it, how much would you want for it? "
 
" WOT rpms?..... Would need to

" WOT rpms?..... Would need to know what year is it. Sorry, I don't have the carb kit.

Joe (30+ Years With OMC) "
 
" 1990 CJ10RESC 9.9, converte

" 1990 CJ10RESC 9.9, converte to a 15. That's alright about the kit. I thought I'd check with you first. Local dealership wants 24.00 for it. Think I could find a better price online? What's your opinion about Sierra or other aftermarket? Thanks "
 
" JD..... Sierra's kits ar

" JD..... Sierra's kits are top quality. The 1990 9.9hp engine has a WOT of 6500rpm. The 15hp has a WOT of 7000. Unless you've changed the exhaust tuning megaphone and other components to make that 9.9hp a 15hp, I keep the rpms down to 6500. Just changing the carburetor on that model doesn't make it a true 15hp.

Joe "
 
" Joe, thanks for your input.

" Joe, thanks for your input. I kind of suspected that, but it is a heck of a lot more powerful. I never turn it much over 6500. I gebnerally stay away from WOT anyway unless I have to. Have gotten it alll the way wide open for just a few minutes a couple of times, just to see how many rpms it would turn over and a couple of times when I really needed to get in in a hurry. I think it runs best at 5000-5800 rpms, and that's plenty fast for me, about 15-20 mph in my 14' jonboat, depending on conditions and load. I'll probably just go with the OMC carb kit. The Sierra is no less expensive. The leak around the bowl gasket is only slight, and usually only when I prime the bulb or tilt the engine, but loose gas does concern me. Also, it has been kind of a hard starter lately at times. Do you think that slight leak could be the problem? Before it's always turned over without much effort. COmpression and spark are still strong. Thanks.
J.D. "
 
"JD... From what you've sa

"JD... From what you've said, I'd assume that the carburetor is fouled, clogged, etc which is causing your problem. Time to remove, clean and rebuild it.

Joe
"
 
" zthing is, once it's goi

" zthing is, once it's going, it runs great at idle and throughout the RPM range. But the leaking gas does concern me, I really don't want a fire on board. I plan to rebuild it. That's the reason I asked about the carb kit. I think the bowl gasket is shot. Maybe I tore it or something when I was cleaning the carb. Thanks for your advice. "
 
" If you are able to turn that

" If you are able to turn that many RPM at WOT, you may want to consider a larger diameter or higher pitch prop. I'm not sure of the size on your 9.9, but I would think the factory prop for a 15 is larger or has a more aggressive pitch. If you put that large one on, you should see your RPM decrease to the ideal limit, and you'll gain a little speed too!

Kevin "
 
" Kevin,
I tend to agree with


" Kevin,
I tend to agree with you, but I usually do not get anywhere near WOT. My rpms also decrease big time when I get a few people or a bunch of gear in my boat. Rpms also go way down when the conditions deteriorate., such as a following sea, or going into a heavy chop. Also, I don't have teh cash to buy a bigger SS prop. I was told I could go up to as big as 9.5X11" If I have anything to say about it, I will not go back to aluminum props. They tear up much to easily in the places wher I fish. I had one two summers ago, and it barely made it through the summer. Just ain't near as tough as those SS props. "
 
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