How to mix oil for Break-in of 2-stroke outboard power head


The first 10 hours of use are when you are breaking in your new or rebuilt engine.  It's important to follow these guidelines so that your engine and all it's parts are sufficiently lubricated and will continue to run smoothly in the long run.

Two-Stroke Oil Injection Outboards

During break-in, all new Precision Blend engines should be run on double oil, with the exception of HPDI motors, which use straight gas for break-in.  This means you need to run all PBS-equipped engines on a 50:1 oil mix during the 10-hour break-in period to supplement the oil supplied by the oil injection system.  This additional oil provides further protection during the oil pump setup and furnishes extra lubricating oil during the break-in period. 

Two-Stroke Premix Outboards

Pre-mix engines that normally run on a 50:1 ratio will need a break-in oil ratio of 25:1 during the first 10 hours of operation.  Engines that normally run at 100:1 should be run at 50:1 during break-in.  After the 10-hour break-in period, use the regular oil ratio. 

April 25, 2017 by dennis crowley



A propeller converts the engine’s power to thrust that drives the boat.  As the propeller turns, low pressure is created on one side and high pressure is created on the other side.  The propeller moves toward the low pressure, moving the boat with it.  How well a propeller moves toward the low pressure depends on several factors. 

  • Thin blade (low resistance)
  • Diameter (thrust)
  • Pitch (load)

No one single propeller design will work for all applications.  Hull weight and available horsepower dictate what will work for best for you.  You need to keep in mind the operating range of the engine and select a propeller that will allow the engine to come close to its maximum RPMs at WOT (wide-open throttle). 

Two important terms to become familiar with are ventilation and cavitation.  Both are issues that can occur from poor rigging, improper prop selection, or a damaged propeller.

Ventilation is a problem that means air is being pulled into the propeller from the surface of the water or from exhaust gasses while in reverse.  The ventilation plate on the lower unit tries to limit this problem.  Prop design or high mounting height can be possible sources for this issue.   It is not unusual to vent the prop with some hull designs during hard turns. 

Cavitation describes water that is actually boiling on a surface because pressure has dropped so low.  A damaged prop blade will cause a very low-pressure area behind the damaged area.  Water boils at 212 degrees at sea level.  Dropping the pressure on a prop blade enough will cause the water to boil until it moves across the blade to a high-pressure area.

March 23, 2017 by Sheri Reeves

Tech Tip: Converting Your Outboard Lower Unit to a Jet Drive

So you want to take your boat upriver. That can be tough on the on traditional outboard lower unit. Many boaters prefer to convert their standard propeller driven outboard to outboard jet drive. Jet boats are able to travel across shallow sections of river without damage to the drive.
July 18, 2016 by dennis crowley
Tags: Tech Tips

Tech Tip: OMC Outboard Engine Assembly

The following relates to proper assembly of OMC Outboard Engine Assembly.

• Install .0002" larger jets in carburetors.
• Max timing MUST be retarded 2 degrees.
• Max timing MUST be set with engine running over 4500 RPM & under load. DO NOT STATIC SET MAX TIMING.

July 18, 2016 by dennis crowley
Tags: Tech Tips

Tech Tip: Outboard Powerhead Break-In Procedure

We cannot express enough the importance of proper break-in of your new outboard powerhead. Failure to do this properly can be the cause of premature failure and poor running of your outboard motor.

The following is the procedure for break-in your new powerhead.

July 18, 2016 by dennis crowley
Tags: Tech Tips

Tech Tip: Mercury V6 Engine Assembly

The following procedure relates to Mercury Outboard engine assembly.

• Check latest Mercury Service Bulletins online (Google It or just contact us).
• Install .0002" larger jets in carburetors.
• Max timing should be retarded 2 degrees.
• Remove advance box if installed.
• Remove idle stabilizer if installed.

July 18, 2016 by dennis crowley
Tags: Tech Tips