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Johnson 99hp and 15hp four strokes

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wynand_n

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"I am planning to by a new Joh

"I am planning to by a new Johnson 9.9hp four stroke, but looking at the specs, were surprised that the 15hp has exactly the same engine displacement and everything else the same right down to mass and dimensions.

My question, since the two engines seems identical, what causes the difference in horsepower? Is it a different carburetor, or just jets, timing? Is it possible to tweak a 9.9 to 15hp cheaply (less than difference in purchase price)
Or is the 9.9hp in fact a 15hp and people get ripped off...?"
 
"No. My company actually build

"No. My company actually build boats from ocean going yachts (main business - 65ft and smaller currently a 44ft under construction amongst others), 19ft trailer sailor keel boat, bass rigs, speed boats etc down to rc bait boats.

We have a small mini pro bass boat, 14ft in length fully kitted out and a poor man's version of the same hull sans flatdeck, IOW open boat with only three transverse seats/bunks fitted to be a basic and cheap fishing boat for local lakes. A 9.9hp would move her along nicely for its intended purpose. I have a waiting list for these type of "bare" boats..."
 
"Wynard, I don't have much

"Wynard, I don't have much recent history with the latest 9.9/15 hp Johnson 4 strokes. I do know that the first generation were not that reliable. Most likely difference in the 2 engines is carb jetting and camshaft...someone will correct me if I'm wrong."
 
"9.9 is rated at 5000 rpm....1

"9.9 is rated at 5000 rpm....15 is rated at 5700 rpm...they been doing that for years..i remember in the 60,s a 18 hp and 25 hp evinrude weighed the same..77 pounds...there was a thousand rpm difference in the rpm they were rated at...i bought the 18 because i thought it would last longer turning fewer rpms...it did last well til someone stole it...i then joined the rat race and jumped to a 50 merc....everyone thought i was a speed demon..."
 
"Carl, they would have to chan

"Carl, they would have to change something to get the extra 700-1000 rpm. Different stroke, larger carb or jetting. Less things to alter on the 2 strokes."
 
yes i know Rollie...i wasnt ab

yes i know Rollie...i wasnt able to find what they changed tho...the specs i did find were exact same unless i overlooked something...i would suspect carb and/or maybe exhaust..i just wanted him to know about the rpm thing....
 
"Suzuki built all the 4 stroke

"Suzuki built all the 4 stroke Johnson's for the past 10 years or so but that (contract) ended last year.

Since OMC/BRP never announced a new builder, in fact the last word from them was that they were going to totally scrap the Johnson line alltogether, anything still on the market is most likely "old stock" Suzuki built models.

For that reason alone (possibly going to become an orphan) I would tend to stay away from the Johnson 4 strokes."
 
"Graham:
Not quite correct.

"Graham:
Not quite correct.
The first generation of the 9,9 4 strike was built in Hong Kong at the OMC factory. Then came the 15 and later even the 9,9 with bigger displacement built in US.
The Suzuki engines started with the 25 and up.
Check the ignition system components and gear case, they are all OMC/BRP!
Have had several of the 9,9 of both versions, and reliable -YES! Only problems was the power pack. Used them summer and winter, sun and snow/ice. A bit tricky first start in winter morning at minus10C, but after that - one pull all day!"
 
"Morten, I was sure as well th

"Morten, I was sure as well that the first 9.9's were OMC engines. I beleive the gearcase was the same as the 9.9 2 stroke. In our area, (west coast Canada) they were not reliable. They were used as kickers for trolling salmon. Not many were sold and those that were spent alot of time in the shop for various problems. (compared to the other 4 strokes on the market at the time) Proof is in the fact they didn't hang around long."
 
Thanks Morten for the clarific

Thanks Morten for the clarification - are you aware if Johnson's are still being produced. I was half quoting an article I read last spring which stated that with the end of the deal with Suzuki that they intended to scrap the Johnson line completely..
 
"Graham:
I think no one may a

"Graham:
I think no one may answer at the moment. The melt-down of economies around the world has hit the boating industry quite hard, and things seems to change from one day to another.
Have heard rumors that the 'Johnson line' might be produced outside US intended for countries with less stringent emission rules and lower production costs. However just rumors!"
 
"To Morten Ringvold:
Morten,

"To Morten Ringvold:
Morten, I have a 15HP Johnson 4 stroke that has a remote throttle and shift controls. My problem was that when installed the new cables I did not rig it properly and I cannot get the higher RPM in Forward gear. As I move the shift down (forward) the speed will increase slightly and if I go all the way the engine will either die down or slow to the lowest RPM. I tried adjusting, today, the upper (throttle) cable by turning the trunnion nut in and out to see if it will make the difference but I caused another problem. The engine will not start even when I returned trunnion nut to its original position. It will only start if I choke it but in very high RPM for a second or two. I am very puzzled and perhaps you guys can help.
Thanks
Gene"
 
"As I mentioned above, first s

"As I mentioned above, first start in the morning was always a pain in the butt. Only way was full choke and full throttle. That was common for all of them. Mine were all tiller, so no running back and forth to adjust throttle!
Adjust engine idle with cables not attached, then hook them up. The engine much reach operating temp before You may start to drive, a draw-back on carbed four-strokes versus two-strokes.
However after first start every morning, just one pull, no choke and off it/they went."
 
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