Mercury 2 + 2 125HP

**pbxcomm** · 05-24-2020, 02:24 PM

Hi all,
Some time ago I had posted information on a Mercury Outboard 2+2 125 HP. I asked about removing the rev limiter to run the motor at 5500. I was advised against this..
However, what I've been running into on these motors is a bit disturbing. Here is why:

A second rebuild has turned up the same issue. That is, a needle bearing missing on the lower main bearing. That's right this is my second 125 2+2 rebuild and both 125's have 23 needles in the lower bearing, should be 24. So to confirm I was counting correctly, I had two different buddies count two different times on both motors. What they saw they could not believe.
Now this may be a coincidence, but I doubt it. Is this why they vibrate above 5250 and could come apart above the RPM? Did mercury have a run of these motors with a missing needle?

What's going on here?

**Dave Strong** · 05-25-2020, 10:56 AM

Originally Posted by pbxcomm

Hi all,
Some time ago I had posted information on a Mercury Outboard 2+2 125 HP. I asked about removing the rev limiter to run the motor at 5500. I was advised against this..
However, what I've been running into on these motors is a bit disturbing. Here is why:

A second rebuild has turned up the same issue. That is, a needle bearing missing on the lower main bearing. That's right this is my second 125 2+2 rebuild and both 125's have 23 needles in the lower bearing, should be 24. So to confirm I was counting correctly, I had two different buddies count two different times on both motors. What they saw they could not believe.
Now this may be a coincidence, but I doubt it. Is this why they vibrate above 5250 and could come apart above the RPM? Did mercury have a run of these motors with a missing needle?

What's going on here?

Don't know what to tell you on the needle thing, but running over 5250 is not good. Its a harmonic deal that creates a vibration that knocks the crank out. The very first 2+2 motors had a rev limit of 5500 until they started knocking cranks out, fix was to drop the max rpm to 5250.

Dave

**pbxcomm** · 05-25-2020, 06:42 PM

Originally Posted by Dave Strong

Don't know what to tell you on the needle thing, but running over 5250 is not good. Its a harmonic deal that creates a vibration that knocks the crank out. The very first 2+2 motors had a rev limit of 5500 until they started knocking cranks out, fix was to drop the max rpm to 5250.

Dave

Got it thanks...