Maximum allowable RPMs on Johnson 150

[Law128]

Greetings: a month ago I purchased my first boat, a meticulously maintained 1993 20' Grady White from an old-timer who bought the boat in 1996. It is obvious he took great care of the boat and the motor which has 800 hours of use but boat and motor are immaculate. He had no family and was strickly a fisherman. He claims to never have run the Johnson 150hp motor above 3,500 RPMs and I believe him because all the boaters in his marina who new him said he was very cheap and did not want to consume the gas.

My question: If this motor has not exceeded 3,500 RPMs during the last 14 years of use, will I cause damage bringing the RPMs up to 5,000 after all this time? I am new to boating and I am fearful I could damage a motor which has not run at such high speed in 14 years.

Thanks very much for your opinions.

Lawrence

 

[Bob_VT]

Re: Maximum allowable RPMs on Johnson 150

Welcome to iboats.

Use the motor the right way and run it!

I would get a proper manual and do ALL the required maintenance and I would pay special attention to the impellar and also de-carb that motor.

Read this http://forums.iboats.com/showthread.php?t=158076

 

[coolguy147]

Re: Maximum allowable RPMs on Johnson 150

decarb and impeller first off.

 

[Law128]

Re: Maximum allowable RPMs on Johnson 150

Thanks Bob and Coolguy: I have 2 follow-up questions;

1. Can the decarb process be done with the boat in the water or will the excessive smoke be an offensive gesture to other boaters in the marina?

2. Do you know of a source to find a manual for a 1993 Johnson 150?

Thanks guys!

 

[ezmobee]

Re: Maximum allowable RPMs on Johnson 150

Here's your manual http://cgi.ebay.com/1993-Evinrude-J...-Manual-S-/140216653655?pt=LH_DefaultDomain_0