I just ordered a 300 R with 1.60 sportmaster to go on my 2006 21xd Comp. What prop are you guys running on the 4 strokers. I have been running a worked 28 Promax on my 300xs with 1.75 sportmaster. Any idea
Richard aka Kllr Bee
I just ordered a 300 R with 1.60 sportmaster to go on my 2006 21xd Comp. What prop are you guys running on the 4 strokers. I have been running a worked 28 Promax on my 300xs with 1.75 sportmaster. Any idea
Richard aka Kllr Bee
That same prop should run pretty good on it. A 29 bravo1 XS should run pretty good also.
‘17 Bullet 21 SDC ‘20 Merc 300R 1.60 SM 1E081012
Don’t have one, but would like to. But from everything I’ve seen, they are the hardest motor to prop unless you have a nice bank account. That’s to the potential of the motor.
2008 BULLET 21XD 2007 Merc 300xs
A 1:60 is probably going to be in the 28 pitch range. I have a 1:75 with a 31 max5 at 6200 rpm
These motors like alot of blade surface area. Try the bravos or hydromotive. They do like the max 5. I ran a 31 max 5 pretty good. On a SST. I didn't like the 1:60 on my motor and ended up getting a 1:75 after I damaged the first one.
2020 Allison XB 21
Merc 300R
2018-SST Bullet
Merc 300R
Bullet 20XD
300XS DBR
With the 31 max 5 and 1:60, what was your top speed and how much did you lose going to the 1:75?
2008 BULLET 21XD 2007 Merc 300xs
Definitely look at a Mad EFI, they are expensive. After buying a couple of Bravos from slung blades you will pay for a Mad EFI. I really like my Mad EFI, on a Comp hull I would be looking at a 29p or 30p. I also like the Performer BC lots of slip getting on plane but drives great. I have the 1.60 on my XRS and I like it, it has been a challenge to prop. Lots of test time with about 6-8 different props. Probably have more test time then fishing, lol.
2019 Bullet 21XRS
2019 Mercury Racing 300R
Thanks guys. Looks like I will have some testing ahead.
Richard aka Kllr Bee
See the ads for the new Ventura?
2011 Ranger z521/2023 250ProXS
A buddy of mine has a 300R on a 21XD and his favorite prop for the money is a PowerTech BRV5. That is what he generally runs as a fishing prop. From what he told me they have to be worked by Croxton to run though. If he's not running that prop he runs a Bravo.
Something to also consider, if you don't already have one is a hydraulic jack plate. When I propped my v8 on my 20' XDC I never could find that "sweet spot" like I was able to with the 2 strokes, if I was high enough to run out on top it wouldn't get out of the hole very well (or not at all), and when low enough to come out good top end suffered. I added the hydraulic plate and it really helped. That was on my 20xdc with a 300R. I now have a 21SDC and it comes out of the hole better than my 20'er ever did (comparing both with hydraulic jack plates).
I'm running a 32 MAX 5, only because thats what I was running on my 20XDC, same motor and prop on my 21SDC and comes out good, but lacking a few hundred rpm's on top because of the 32, so will be selling the 32 MAX 5 pretty soon.
If you still have opportunity to switch your order to 1.75 ratio, you should. I got the 1.60 and ended up buying a used 1.75. On a truly light 21xd you might be ok, but you would like much better with 1.75 especially if you want to prop it out for best top end. With 1.75 you could run a 32 max 5 and be 100+ on a true comp hull.
I have a 1.62 sportmaster on my 300xs that I have ran for 13 years. That is why I ordered it with a 1.60. Also I have a hydraulic jack plate now so I think my setup should be a swap plug and play.
Richard aka Kllr Bee
killr bee, I have a like new 31 MAD EFI for sale!
I would change the order to a 1.75 even if you are running 1.62 now. Mercury does not recommend the 1.60 on a single engine setup unless its a really light boat. The 21 comp is long and is not what I would consider a light boat. The 1.6 gear is too tall and it pulls the engine out of the powerband...yes you can prop it down but by the time you prop down to get the acceleration back you dont have enough prop to run a number and if you get too much pitch the acceleration is gone and the engine falls on its face. We have tested this many times and the only situation I have found that 1.60 works is on the 450R.
Long story short, if you come to me for a 300R you are getting 1.75's.
Fastbass Marine LLC
We specialize in NEW and USED ALLISON BOATS, Blazer Boats, Platinum Mercury Marine Repower Center, AquaTraction Flooring, and custom marine electronic installations on beautiful Kentucky and Barkley Lakes.
2022 Allison XB-21 BasSport Pro Elite
2022 Mercury 450R
2012 Bullet 21ss
2005 Mercury 300X
https://youtu.be/FOnAGNWOgZ0
+1.
2020 Allison XB 21
Merc 300R
2018-SST Bullet
Merc 300R
Bullet 20XD
300XS DBR
Thanks for the info. I don't want to have to go with hard to find high pitch props. Plus I am not racing I am a bass fisherman that likes to go fast. BUT, check my record I know how to go fast also.
Richard aka Kllr Bee
It's your choice, but fwiw Tim Powell and his crew have probably put more hours into researching and testing this motor on a bass boat than anyone in the country.
I am still breaking Motor in but I have hit 88 at 5900 rpm's during a short wide open burst with my 28 Promax that has cup added for bow and stern lift done by Performance Propellers in Soddy Daisy,TN. Hole shot better than old 300xs. I carry full bassproshops store in my compartments and a Minn Kota ulterra on the nose. Water pressure gauge is still pegged, so I still have room for more lift on jackplate. I think I will keep 1.60 gears.
Richard aka Kllr Bee
Last edited by kllr bee; 07-11-2023 at 12:36 AM.