Johnson 130 High Altitude Jetting

[Dadicus]

Hi,
My son bought a 1850 Crestliner Fishhawk in Minnesota last fall, and brought it home to Utah. It has a 1995 Johnson 130 on it. The altitude at our closest lake is 4500ft, and more like 7000-8000 feet at the lakes we fish most often. The boat runs decently (though very rich) on cold days (35+mph). But on warmer days it will flood and begin misfiring above 2000rpm.

I've cleaned the carbs (twice), checked the spark, checked the floats and seats, confirmed that the electric choke is in the proper position, and run several tanks of gasoline through it. At this point I'm convinced that we need to change the high speed jets.

The high speed jets on it now are the standard 70d ones that are designed for sea level to 2500ft (I think). Does anyone know the size jets I should be running on this boat at 4500 to 8000 feet above sea level?

 

[racerone]

The local boat shop would likely Know what size to go to.-----I would try a 67D on that motor if I was running at 5000'.----What are the compression numbers?----Try running with timing light one cylinder at a time and see how spark behaves.

 

[Dadicus]

The local boat shop would likely Know what size to go to.-----I would try a 67D on that motor if I was running at 5000'.----What are the compression numbers?----Try running with timing light one cylinder at a time and see how spark behaves.

Thanks for the reply, and the 67d recommendation. The local boat shops are a bust--which is a little frustrating since all I really need is a few numbers out of a tech bulletin. The compression numbers are good--140 to 150 on all four. Thanks for the tip about the timing light, though I'm not sure exactly what you are suggesting.

 

[racerone]

You run with a timing light.----Observe the flashing light.----If there are spark issues the light will not flash steady.