Hi, my brother asked me this the other day and I can't answere it. Hopeing someone could help. What is the max RPM's a 125 Merc 2 stroke should turn at WOT.

My brother has a Alumacraft Throfey 17 ( alum, deep V) with a 125 merc turning a 21 pitch prop. The motor was rebuilt two years ago, before the rebuild it would turn 5500 rpm and get 49 mph. The shop that rebuilt it is a very respectable shop. they said they  set the motor up on the transom for better porformance. It does sit a few inches higher on the transom than it did. Now it turns 6000rpm and runs 53 mph ( GPS).  The boat has a wicked hole shot

He is just wondering if 6000 RPM is to high?

That wasn't that Black Hawk rebuild place in the Pittsburgh area was it?

BTW, while a 115 can probably do 6k alright, I'm not so sure you're not headed for a premature meltdown running at that RPM for very long.  

I am running around 5800 RPM with a 24 pitch Lazer 2 on my 175 Procraft at WOT.

Thanks for the info. I also thought that 6000rpm was OK but maybe on the cusp of to much. I have been trying to get him to get a new prop. When I check Merc's prop selector, it says that a 24-26 pitch prop would be the best for overall best performance. I think he is going to try a few different ones out this year. He needs a good all-around prop. the boat is use for double duty. He fishes out of it and also takes the family out in it and tubes, wakeboards & ski's behind it. with the 21 it pull a skier out of the water with ease, but that 6000rpm is worry some.

Cart7. do you mean "Black Birds" up here by Pittsburgh? If you do. they didn't do the rebuild, but did the machine work on the block. Why is there something I should know about them? I know many guys that have had motors rebuilt by them and have heard nothing bad.