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Nissan 98 4Stroke Wonbt plane out a 12b jon boat

iamjcl

New member
"I've got a 2004 Nissan 9.

"I've got a 2004 Nissan 9.8 4S, (bought used - great shape - can't have many hours).

Changed crankcase oil and foot oil when I got it. Started and ran OK, but wouldn't turn up enough to plane out my small (flat bottom) 12' jon - just me in it.

Pulled the carb, cleaned fully (was very clean to start with), re-assembled and installed. Put in new plugs. Idled smoother, starts 1 pull everytime now (took maybe 1-3 before), but still turns up to the EXACT same rpm everytime. My daughter and I took it out and we ran it anyway, for about 20 minutes WOT, and it probably never wavered 20 rpm the entire time.

Changed the fuel filter. Checked the air box. Cheked the tank vent. Checked the tank itself. Made sure the linkages were getting the choke out of the way, and the throttle was opening fully. Pulled the carb AGAIN - still clean - cleaned again just for fun.

Still turns up the same - just doesn't have but about 6 HP I think. Runs great for a 6HP! Very smooth, quiet, starts great, idles great. Just not enough power!

I don't know enough to check the timing, but the belt etc... look brand new - How to check / adjust?

Both cylinders are firing (both plugs look identical after running), and if I pull a plug, it has less power (either plug). So I'm not dragging a cylinder (maybe weaker spark - but they are both firing).

Bulb is firm etc... This thing looks pretty simple - gotta be something easy.

Oh - can't read the number on the prop, but eye-balling it it isn't a tall prop or a large diameter. Looks just like the ones in the store (white, aluminum, nothing special). Also, the load I'm pushing is really minimal. The guy that had it was using it on a 11' air-floor inflatable. My jon should be a bit easier on the motor, I'd think.

Anybody ?

Thanks!"
 
It may be as simple as you hav

It may be as simple as you having too high of pitch for your application....Or a lot of other things. Take it into a dealer and have them check it out so that you have a baseline for comparison.
 
"I have had an 18 horse 4S Toh

"I have had an 18 horse 4S Tohatsu for about 5 years. It is mounted to an old 13.5 foot Boston Whaler. The motor has always run good, however it has always had a problem bringing that boat on plane. These new four strokes are heavy on small boats especially when both a heavy guy and a heavy motor are sitting on the stern."
 
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