Low RPM at WOT

[MillsyMO]

I was hoping someone could give me some insight. From everything I’m reading my AR250 should be turning 7600 RPM at WOT. My starboard engine is running 6900 and Port is 7100. I found the thread to adjust it fully to the bump stop and they were slightly off but now adjusted to full bump. I’m in MO and operate at approximately 850’ above sea level. Is this something I should bring up to the dealer or is there an easy fix? Thanks for any input.

 

[HangOutdoors]

I would check your oil level to see if it is over filled. Then I would check the spark plug condition.

 

[MillsyMO]

I did the check oil level and it’s spot on. I have not checked the plugs but now that I have close to 40 hrs on them I’ll check them out. It’s going in for service in 2 weeks so I figured I’d ask them about it also.

 

[HangOutdoors]

I did the check oil level and it’s spot on. I have not checked the plugs but now that I have close to 40 hrs on them I’ll check them out. It’s going in for service in 2 weeks so I figured I’d ask them about it also.

@MillsyMO When you say spot on, it is below half then? TBH I would reverify and recheck everything the dealer does for the service once they are done. It is not uncommon for a less then adequate job to be done.

 

[MillsyMO]

There was 2 holes on the dip stick and it was at the top hole. It didn’t have any writing on it but I assumed from reading other dip sticks it meant the top hole is full and bottom hole means add oil. I changed the break in oil and filter at 13 hrs and put in 4 qts that the kit came with.

 

[HangOutdoors]

You most likely have too much oil in there. Should be half or preferably a bit less. It will drop your RPM's and potentially clog your air filter with oil at the full mark. Also when you change oil, always fill just above low first and make sure engines are level, or wait to you get on the water then check the oil again. Bring it up to 25% or slightly higher, but no more than 50%. After taking some oil out, I would also check your current air filters. If they smell like oil or it is visibly stained that will inhibit engine performance. You could pull them and make a run or two without them in and with them in to see if there is a difference.

There are a lot of threads here regarding this and good reading from many, many members.

I always check the oil on every outing once I come out of the no wake zone or after a few minutes. I carry my oil extractor a filter and oil with me in case, in my Boat box that I leave in my tow vehicle.

 

[MillsyMO]

Wow, these engines are that finicky? I thought my Harley was bad. Lol. I have to run it a 1/2 qt low and installed an after market breather for the oil dipstick so it would stop blowing oil out of my air filter.
I will drain some out to around the half mark and check my air filters tomorrow. Thanks for the info!

 

[HangOutdoors]

This would be potentially the beginning of your journey on the low RPM's. Once you have this squared away, then if the RPM's are still on the low side, you can keep exploring. I would probably estimate if your RPM's are between 7300 and 7600 you are in the zone. Remember, the humidity and temperate will also affect RPM's. Although my engines are a bit different, in April I get circa 200 more RPM's than I do in the mid summer. I

 

[MillsyMO]

That definitely makes sense! My motorhome was struggling in the 97 degree heat pulling it to the lake when normally it pulls it just fine. Also I see Riva makes a high flow breather kit for it and the crank case. Maybe I’ll check into that and I’m reading about deleting the ribbon. Does anyone know if any of that will void warranty? I had issues with Harley on a brand new bike a few years ago is why I’m asking. Anytime you go deleting EPA stuff they frown upon it.

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[HangOutdoors]

You won't get much with the Ribbon Delete. Search it here on boards. There is really not much you can do to get more speed or increase the RPM's beyond what is stock. Unless you put a ton of cash and time into modding the engine. I would recommend getting it to run optimally the way it is and enjoy your boat. If you feel you want to do engine mods, I would recommend reading up the routes people took here on the forums, the effort and the cost and what realized gain actually was. IMHO spend the time and dough on upgrading or adding things to your boat, like upgraded sound, a chart plotter, if you are in big water and chop do trim tabs. Put Seadek or Marine Mat throughout and get rid of the carpet.... My best mod I think so far.

 

[MillsyMO]

I’m more than happy with the performance. I was thinking more along the lines of just helping it run it’s optimum performance. This boat has been very impressive and I’m very happy with it, though the sound system is pathetic. Probably my number 1 complaint, why the heck can’t I adjust the bass down so it doesn’t just distort and sound like trash?!