Setup Help for 300R

[CPA Basser]

I have a 2015 BasSport Pro Elite that had a 2015 250 Sport XS with 1.75 gears. I just repowered with a 2021 300R with 1.75 gears. I have 8" of setback (3" spacer & 5" CNC jackplate) with wedges. The motor is mounted in the top 2 holes on the bracket. I have the skid planer but no foil. I have dual power poles, a 36V Lowrance TM, with a group 31 AGM cranking battery in the rear middle of the boat under where the old oil reservoir was, 2 75AH lithiums in the tray in front of the ice chest, & 1 75AH lithium in the front of the passenger rear compartment. I always carry a boat full of tackle and a fishing partner.

With the 250, I was using a 27p Bravo 1 as my everyday prop because the hole shot was great, even with a full tank of gas and full livewells. It would jump on plane almost immediately. If I was fishing a big body of water in a tournament, I would put my 28p Bravo 1 FS on because it ran much higher top speeds. It got on plane well until the livewells were full and then it would take a few seconds to get on plane. All of my current props are Bravos.

I only have 7 hours on the new 300R. I have run it with my 30p Bravo 1 and my 28p Bravo 1 FS props. With a full tank of gas and empty livewells, it starts to break over in 2 seconds and is on plane in 1 second (total of 3 seconds to get on plane). No difference with either prop. Running the 30p with 1 solid vent plug and no vent plugs in the 28p. I haven't been able to run the 27p prop yet. It takes a total of 5 seconds to get on plane with the livewells full, same with both props. I am tucking the motor all the way in to get on plane and keeping the jackplate at about 3/4 on the gauge, well below the pad. Adjusting trim and/or jackplate position hasn't seemed to improve the hole shot.

I thought the hole shot would be better with the new 4 stroke with all of its torque, but my hole shot has gotten worse (although to be fair I am using larger props - the 27p Bravo 1 may do great when I get to try it). I want to find a prop/setup that will let me get on plane right away for when I fish small bodies of shallow water.

I also have noticed a significant amount of vibration that I can feel with the new motor.

Would a 5-blade prop, like the Max 5, help with hole shot and/or vibration? Some of the info I have read suggests that this might be the case. If so, should I consider a 28p or 30p? With the power poles and cranking battery in the rear of the boat and tackle in both of the rear compartments, I am always heavy in the rear of the boat. Would I need to consider a Max 5 ST or with a lot of weight in the rear, would the stern lift from the standard Max 5 not be an issue?

I am still in break-in so I have no idea what the top end performance will be yet, but when I ran the 30p Bravo 1 for 1 minute at full throttle in the first 2 hours, I was able to turn 6,200 rpms and 85 mph without raising the jackplate from the 3/4 level on the gauge and without trimming excessively. Neutral trim with the old 250 was at 6.5 on my merc monitor. When I increase throttle past about 5,000 rpms, the boat wants to lean left a bit and seems to respond well to some additional trim but I had my wife with me and didn't want to trim much past 7.0 on the trim gauge. Would neutral trim on the new motor likely be different from the old one?

Appreciate any input or guidance. I know it's a long read. You guys are an incredible wealth of knowledge on these boats and motors. Thank you for being willing to share your knowledge to help the rest of us get the performance out of these boats and motors, safely!

[River Rocket]

You have the worse case scenario. The 250XS with 1.75 is probably one the of the best hole shot motors Merc has made in the opti and R time period for a heavy boat. You had a really great hole shot combo. The 300R will absolutely take it up top, but I'm not surprised with your load that you are not that impressed (read next line). The motor is heavier and the poles put a lot of weight off the back of the boat.

I made the switch from a 300XS 1.62 to a 300R 1.75. You can go back and read some of my posts. My motor took at least 20 hours to come a live, so it will get better. I wouldn't change anything or spend money on anything until you get some more hours on the motor.

I never had a vibration on a 4 blade. The 3 blades do vibrate.

The max 5 is a great prop and will probably win you over. Don't be afraid to vent the props. Even with the R. I ran 8 open holes in all my props.

Neutral trim can vary and I would find the number on your new setup. It is also a good time to double check motor height. That has probably changed with a new motor as well.

[Tim Powell]

SC trim will have to be calibrated after the engine swap, if this wasnt done your trim numbers will not be the same.

The big SM case likes to be ran much higher than the previous SM.

i agree with Geoff, get some time on the engine, it will loosen up. The Max 5 will carry a load better, especially with poles.

[CPA Basser]

Hoping to get some more hours on the motor soon. Finally through break-in. The 30p Bravo has run up to 87 in a short burst at full throttle but the plate can run higher than that run. There is definitely some vibration that is noticeable at certain speeds. I will probably end up trying a Max 5 before I am done but agree that more seat time with the new motor is in order.

What would make the boat want to lean left more as speed increases? It seems very level/stable up to about 70 and then as speed increases above the low 70's, I have to trim it out more to keep it from leaning left.

Thanks for the input and help!

[Gary Morgan]

Being under trimmed will enhance the torque effect of the right hand rotating motor and push the left side of the boat down. If you are fairly well balanced, when you trim out further the torque effect will be reduced and level the boat out.