2120 with Yamaha 150 4 stroke

[Luv2fish]

I just bought this boat and had it out this weekend. I noted that it would top end about 28 MPH and 4700 RPM. I was wondering if this was consistent with what other people were seeing out of similar setups. I had a full tank of fuel and 3 people on board. I was thinking the motor should get up to about 5500 RPM. Any suggestions are appreciated.

 

[DaleH]

Try this post here. and hopefully other 2120 SC users will chime in. From everything I've been reading even on other boats, I think those motors are coming from dealers with too-high a pitched prop on them.

 

[Luv2fish]

Thanks Dale. That sounds like what I am looking for.

 

[rplas48]

What prop are you turning? You are somewhat lugging the engine as the range is 5000 to 6000rpms. The closer to 6000 the better. With the engine trimmed and tabs retracted I turn 5500rpms and 38mph. Just about the same results with the 13 3/4 X 17, 14 1/4 X 16 and 15 1/4 X 15 props. Search my previous postings for performance of the 2120 SC with the F150.

Ray

 

[FISHON]

I turn a 14.5 x 15 yamaha reliance prop and get 5500 rpm solo with a full tank of fuel , speed is in the upper 30's. I cruise 4000 to 4500 depending on conditions.

 

[bigeye2k]

You have the wrong prop I replaced mine last season and man what a difference. Went from 4900 max rpm to 5800. Better top and and faster plane. I can't recall the prop size but it was one rangertim tried with great success
Look for RANGERTIM post he tested a few prop's.

 

[Ranger Tim]

Remove the prop you have and look on the back side of the hub for what size it is. Start with that information to determine where to go next. Post it so we can know too. Any bait wells or other non-standard stuff onboard?

BTW, grease the splined shaft if necessary. I use a green Quicksilver branded grease that my mechanic recommends, but that's not that critical. Keeping it free from corrosion is, however.

I also use one of those floating prop wrenches in case I have to switch to a spare prop when on the water.