Johnson performance
 

I took my V20 out today for the first time since may. Engine is a 1985 Johnson 150, Top speed was exactly 30.0 mph at 4500 rpm with the engine trimmed all the way up. I ran a 6 gallon tank of gas/oil and a full can of seafoam till it got to low to run.

On that six gallon tank with about an inch of gas left in the bottom (maybe a gallon?) i got about 6 miles. I should get better mileage than that, right?

My only other concern was the top end rpm of 4500 rpm. I read on the prop that its a 15 1/2 x 14. It seams i have a "dead spot" in the throttle from after it engages in gear to about 9 1/2 o'clock. Is this normal?

Other than that she is very strong and ran good. No electrical problems with the motor. :sun:

How are the carbs? When was the last link and sync done? Are you sure your getting full throttle? Your milage sounds a bit low, but the 150 cross-flow is a THIRSTY pig(espescially if it isn't propped right).

Not too sure on the carbs. It fires right up so i would think they aint too bad.
I don't even know what link and sync is :head:. Is that the carb linkage?
I had the throttle pushed down as far as it would go. What else is there to check?

Also, after the first run i took the doel-fins off the cavitation plate, only difference i noticed was it was a little more stable in turns with the fins on, otherwise i noticed no difference.

Also i found and OMC stainless prop 15x17 for $40. Is that too much prop?

It should be worth a try. The link and sync is the carbs and timing linkage. If it is off the timing may not go all the way up which will KILL your fuel milage.

What is required to check the link and sync?
Maybe its time to buy a Seloc manual for this outboard.

I read in another thread a member was having the same issues i am having and everybody said to move to a smaller higher pitched prop.

I just hate to spend money on something that wont help. It wouldn't be so bad if i was working, but right now i am on workers comp and it sucks.

Believe you should WOT at about 5,400 rpm and hit high 30's mph if the engine's still making proper hp.

My 2000 Johnson 150 would run 42 mph at 5500 rpm on my 79' V-20.

His old crossflow isn't going to run quite as strong as a newer looper. He should be turning up to about 5300RPM's WOT and I would think high 30's to maybe 40 is possible if all is right with it.

I am beginning to believe this big *** prop is my trouble. The 15x17 i found for $40 was sold before i could call. Based on what i have read through here i am leaning towards a 14.5x17 prop. Right now i am swinging a 15.5x14 and also have a 15.5x15 aluminum (spare) that does even worse.

I put my throttle wide open, and yes, all carbs are wide open. So my issue is not there i believe. I was able to run it on the hose and use the rest of my sea foam out of my 6 gallon tank that i couldn't use when running.

The previous owners have put some money into this motor. She cranks within two seconds now. :sun: Also what should my compression be?