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Johnson 115 V4 Larson 186 SEI Poor Performance

R

raemcmullen

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"I'm looking at buying a L

"I'm looking at buying a Larson 186 SEI which is fitted with a Johnson 115 V4 outboard motor, both the engine and the boat are year 2000.

On a test drive everything seemed ok with the boat, but when I opened the throttle up, the boat was only revving to 4000 rpm and would only do 25 mph.

Also during the test drive, the boat seemed to lose power for a little while and the rev's died off to around 2000 rpm.

We then took the boat out for another test the following day and the boat didn't lose any power but again wouldn't rev past 4000 rpm, the boat is kept in a marina, so is in the water all the time.

Does anyone have any advice on this matter and would you reccommend me to still buy the boat if the problems are easily rectifiable....?"
 
I would take a compression tst

I would take a compression tst first to make sure all cylinders have good compresion if they are good I would suspect a fuel problem(clean carbs) then run it again and see how it runs
 
"Rae...
I have that same engi

"Rae...
I have that same engine, although slightly older on one of my boats. Propeller choice can have a huge effect on engine performance. The 16.5 ft Cadorette ski boat that it is on varies of about 3-4 mph at WOT using either a 17 inch or a 19 inch pitch prop. Doesn't sound like much but the difference in engine RPM is much bigger. The smaller the pitch of the prop, the higher the engine will rev at WOT. At 4000 RPM, that thing is about 1000 - 1500 below where it should go. It should also go up to about 30-35 MPH (depending on hull design, boat weight, water / wind conditions, bla bla bla...) Prop selection may very well bring the enigne and boat speed up to those numbers. I use the 17 inch prop on my boat for everything and pretty much never use the 19 ever. I'd let you borrow it, but I'm in Canada and its going to be a little tough getting it to you to try for an afternoon

As John J said, a compression test is always a good idea when buying a used boat. Other fuel problem to cause that 2000 RPM could be water in the line.

Wrench"
 
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