Re: getting more speed out of 90 hp johnson
Old thread but heres my 90 story. 1981 Checkmate Enticer. Crank rated 90 HP . In a way I am the original owner. I went down with my dad to pick it up at the dealer in 1981 and Ive done all the maintenance and most of the driving since it was new. Last year I gutted it and replaced the interior.
We ran that boat forever with the 19 pitch OMC stainless prop as the primary prop. On the lie-o-meter it showed 53 at 5800 back in the day. It still shows that since it was restored ( and speedo changed ) but the GPS ( 3 different ) is saying 49 mph with that prop. We skied with it for years, pulled tubes and had 4-5 people in the boat doing it. Recently I put a set of 140 Johnson heads on it and a 17 pitch 4 blade Solas stainless prop. It pulls like a tractor and tops at 46 mph on the GPS . With the 19 pitch it should be even faster and I'll try it out saturday. I'm not saying all 90's should run like this. I'm sure most don't but I have great compression on all the cylinders and heres the most important part . In 1981 Johnson just figured they'd put 1 5/16" carbs on everything. Later they started really cutting back on venturi sizes which helps out on lower end but doesnt do much or the top end. Ive seen late 115's ( same as the early 140 ) that had 1 3/16" carbs and late 90's with 1 inch carbs. Find yourself some 1 5/16 carbs and jet them per 1981 standards. A set of 78-82 140 heads and it'll really wake up. JOHNSON FLOAT LEVEL IS VERY IMPORTANT. Do it right.
Old thread but heres my 90 story. 1981 Checkmate Enticer. Crank rated 90 HP . In a way I am the original owner. I went down with my dad to pick it up at the dealer in 1981 and Ive done all the maintenance and most of the driving since it was new. Last year I gutted it and replaced the interior.
We ran that boat forever with the 19 pitch OMC stainless prop as the primary prop. On the lie-o-meter it showed 53 at 5800 back in the day. It still shows that since it was restored ( and speedo changed ) but the GPS ( 3 different ) is saying 49 mph with that prop. We skied with it for years, pulled tubes and had 4-5 people in the boat doing it. Recently I put a set of 140 Johnson heads on it and a 17 pitch 4 blade Solas stainless prop. It pulls like a tractor and tops at 46 mph on the GPS . With the 19 pitch it should be even faster and I'll try it out saturday. I'm not saying all 90's should run like this. I'm sure most don't but I have great compression on all the cylinders and heres the most important part . In 1981 Johnson just figured they'd put 1 5/16" carbs on everything. Later they started really cutting back on venturi sizes which helps out on lower end but doesnt do much or the top end. Ive seen late 115's ( same as the early 140 ) that had 1 3/16" carbs and late 90's with 1 inch carbs. Find yourself some 1 5/16 carbs and jet them per 1981 standards. A set of 78-82 140 heads and it'll really wake up. JOHNSON FLOAT LEVEL IS VERY IMPORTANT. Do it right.