Yam 225 TRC Operating Range?

[Alibi II]

Our 2004 GW 282 has the typical Yam 225's. They are propped with the stock 19 ML stainless Saltwater series props. We always have the annual service completed and the boat is stored on its trailer at our home. No bottom paint and no growth. I hve been complaining about the operating range of our outboards while in MX but we have the boat pretty well loaded there. I can only reach 5,000 rpm's and about 38-40 mph with the motors properly trimmed. We had the boat out yesterday after crab and humbolt squid and the ocean was flat enough to try running the boat at max. I can only get 5,200 rpms with 1/4 tank of fuel and two people on board and properly trimmed. Very small load. This was with US fuel so that isn't an issue like we thought in MX. We used to get 46mph and 5,800-6,000 rpms with the same load.The book says 5000-6000 is the normal range.

Can any of you tell me what you are getting for an operating range on you Yam 225's? What are you using for props? Any idea of what the problem could be? Thanks for your help.

 

[Moxsea]

I just had this same discussion with the yamaha Factory rep at the NY Boat show. he is stating that you need to get the boat to rev up to 5.5k to 6.0k with your normal load. if this isn't happening you are probably over propped. And, factor in the bottom paint etc. I currently have 15.25 x 19 props he suggested i demo the saltwater series II with a 17 pitch. I am arranging with a local yamaha dealer for this demo once I'm back in water. I run no more than 5.2K normally loaded WOT.

 

[vtacasteve]

re 225's

If the same engines with the same props were turning 55 to 6000 rpm and now are only turning 5200, then the problem is one or combo of a few things.

A) You are having a slight misfire in one or both of your motors. a bad coil or fouled plug or 1 cylinder not firing (for whatever reason) can easily drop your max RPM by 400 to 600.

B) Your boat has gotten heavier. Water intrusion, water in the bilge, extra weight you are not aware of. 2 or 300 hundred pounds will make a difference.

C) you have bent one or both of the props. A slight bend or chip in your props could verywell drop 2 to 400 RPM.

Since you are running twins both motors have to able to turn their max RPM or the weak one will pull the other one down. Before you just change props to get a higher RPM, check these other things out first. goodluck.

 

[Moxsea]

Thanks vtacsteve, forgot to mention first thing I'll do is connect up for diagnostics. then figure it out.