new short block

[bhs91]

I have a new yamaha factory shortblock and am wondering about the break-in period? the mechanic that put it in was out when i went to pick it up, and the sales area people couldn't tell me with a lot of certainty. the mechanic had said at one point 3 hours, which makes sense, but still not sure.

thanks, BHS

[SpecialK]

Straight from yamaha's HSOforum. This is for a two stroke.

Question

What is the break-in period for my two-stroke Yamaha Outboard?

Answer

New engines require a period of break-in to allow the mating surfaces of moving parts to mate evenly. Correct break-in, as described in your Owner’s Manual’s “Operation” chapter, will help your outboard provide proper performance and longer engine life. Yamaha’s two-stroke outboards have a 10-hour break-in. All carbureted (non-HPDI) engines require a 50:1 gas to oil ratio during the ten hour break-in period. The break-in steps are as follows:

First 10 minutes: run the engine at the lowest possible speed (idle). A fast in-gear idle is best

Next 50 minutes: engine speed should not exceed half throttle or approximately 3000 rpm. Vary engine speed occasionally. If you have a boat that is easy to plane, put the boat on plane (but avoid full-throttle operation), and then immediately reduce the throttle to 3000 rpm or less. Do not go wide open throttle.

2nd hour: go onto plane and reduce the engine speed to 4000 rpm or approximately three-quarter throttle. Vary engine speed occasionally.

Next 8 hours: Take the engine to wide-open throttle but for no longer than five minutes at a time. Let the engine cool between full throttle runs by reducing the rpm to idle or cruising (half throttle).

After the first 10 hours, operate the engine normally.

[SpecialK]

Here is the break in for a 4 stroke Yamaha.

Question

What is the break-in period for my new four-stroke Yamaha Outboard?

Answer

New engines require a period of break-in to allow the mating surfaces of moving parts to mate evenly. Correct break-in, as described in your Owner’s Manual, will help your outboard provide proper performance and longer engine life. Yamaha’s four-stroke engines have a 10-hour break-in period as follows:

1st hour: Run the engine at 2000 rpm or at approximately half throttle.

2nd hour: Run the engine at 3000 rpm or at approximately three-quarter throttle. Increase engine speed as much as necessary to put the boat on plane (but avoid full-throttle operation), then back off on the throttle while keeping the boat at a planing speed. Vary speed occasionally during operation.

Next 8 hours: Take the engine to wide-open throttle but for no longer than five minutes at a time. Let the engine cool between full throttle runs by reducing the rpm to idle or cruising (half throttle).

The break-in maintenance is at 20 hours. For the 10 hours after the break-in and before the service you can operate the engine normally.