RPM RANGE 120 JOHNSON

lakerunner

Seaman
Joined
Jan 14, 2002
Messages
57
Hello to all:<br /><br />I just purchased this engine in December.<br />It's a 1990 Johnson 120. Could someone tell me the RPM range of this engine? The engine is mounted on a 1990 18' Hydra-Sports Fish&Ski and has a Raker 13 1/2 x 20 prop. The RPM at WOT is 5300. Is this about where it should be?<br /><br />Also what parts would be needed to upgrade this engine to a 140 are can it be done? :D
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: RPM RANGE 120 JOHNSON

Thats a little short. The limiter is at either 6200 or 6700 depending on what pack you have. Try raising the motor and look for 6000 with an average load. Especially if the motor is mounted all the way down. The Raker likes to be run fairly high. What a great motor. <br /><br />Don't worry about the difference between a 120 and 140 in that year. You'll never notice the difference.<br /><br />Good luck!
 

lakerunner

Seaman
Joined
Jan 14, 2002
Messages
57
Re: RPM RANGE 120 JOHNSON

Thanks for the info Dhadley. I'll try rising the engine alittle and see what happens.<br /><br /> ;)
 

Kmoonster

Cadet
Joined
Jan 15, 2002
Messages
13
Re: RPM RANGE 120 JOHNSON

Hey great Motor, I have the same year and motor, mine is on a 270V Stratos (17'10") boat. I raised my jack plate up I run mine from 5900 to 6000 WOT. I've had mine for 7 years and check the compression the other day and I have 125 in all the cylinders. The only problem I've had is Power packs, I'm currently waiting on one to install. I lost one about 4 years ago. Power pack should be here tomorrow and I'm going to replace it. Just us Johnson 2- cycle, run a can of OMC Engine Tuner thru it once ever 6 gas tanks of gas, or atleast once a year and the motor will last a long time....<br />Oh!!! I run the same prop except mine is a 22 pitch, same diameter....slow out of the hole but good top end....good luck and keep me informed ;)
 

lakerunner

Seaman
Joined
Jan 14, 2002
Messages
57
Re: RPM RANGE 120 JOHNSON

Hi Kmoonster<br /><br />Ya the more you work with it the better it gets I think it's a keeper. I've been looking around at some jackplates that's going to be the next upgrade. What type are you running on your rig?<br /><br />On a different subject: Are you still running the VRO pump? I've had a couple of people tell me that it's better to disconnect it and run premix. What do you think?
 

Digdug

Petty Officer 3rd Class
Joined
Jan 23, 2002
Messages
77
Re: RPM RANGE 120 JOHNSON

Lakerunner, I have a 1994 Evinrude 120. I am running a 13.25X20 turbo and getting about 5800-5900 rpms and 58 mph on speedometer. My boat is a Stratos 270V same as Kmoonster. I do not have a jackplate yet (looking for one now) but motor seems to do extremely well without it. I have the cavatation plate on lower unit exactly 3 inches above bottom of hull.
 

Digdug

Petty Officer 3rd Class
Joined
Jan 23, 2002
Messages
77
Re: RPM RANGE 120 JOHNSON

Also, I disconnected the VRO on my engine. Very pleased with engine....strong motor.
 

lakerunner

Seaman
Joined
Jan 14, 2002
Messages
57
Re: RPM RANGE 120 JOHNSON

Hello Digdug<br /><br />I haven't been out in two weeks it's killing me :mad: sure hope the weather clears up for this weekend so we can make a run to the lake.
 
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