[stalker170]

I had a post a couple weeks ago on a boat that I had just bought. I was asking the question about jackplates and RPMs of my 1991 115hp Mariner. With some help from the board, I was able to do some checking on some things.The boat has four props that came with it. The guy I bought the boat from needed money, so he sold the boat to me. He had just bought a five blade HIGH FIVE stainless prop. He only tried the boat once since he installed the new prop. He told me he thought the jackplate could go down.She was BLOWING OUT. I lowered the jackplate and it did cure the problem. But the motor at WOT still turns 5600 to 5800. Is this bad? I tried the other prop that came with the boat. It is a LASER 23pitch three blade stainless. She would still turn up into the upper 5000 range but was slower on top end. So, the five blade is better for speed. What do you think about the RPMs, too high or is it ok? Does anyone know the Max RPM of my motor. I thought it would be stamped on the plate where the SER# would be, It is not. Or is she all right to run her at this rpm as long as I do not hold her there for ten miles? Or do I need to increase my pitch? The motor is on a Procraft Stalker170Stalker

[Hooty]

I don't think you'll have any trouble at all running in the upper 5 grand range, Stalker.I think from 5500 ta 6grand is where most two stroke O/B engines really cook.c/6Hooty

[skier]

If I remember right, the Max RPM for your engine (Inline 6) is 5400 - 5800, but as long as you don't cross the 6000 line, you'll be just fineCraig