250 opti SJ

[Roost]

Im building a custom river fishing boat. General specs, 17'6" x 68", .190 tempered bottom, tunnel haul with a finished weight around 2000lbs. I fish tournaments and I want something faster then the guys with the 200 opti sport jets. Ive looked into the 240 EFI and Id rather not go down that road. I really want to put the 250 opti sport jet in this boat. I found a used motor for sale from an engine builder. He will refresh the motor, install different reeds, WSM pistons and do some port work. He thinks the motor will be up around 270hp. I would be getting the motor and jet pump package cheaper then I could get a new 200 opti.

I also have a few questions with gear ratios and impeller pitch vs the 200 opti. I see the 250 has a slower pump ratio. Im curious if the 200 and 250 pumps use the same pitch impellers or if the 250 has a more aggressively pitched impeller for more top end?

Without getting into to many more random details im wondering what your general thoughts would be on this motor and build.

Thanks- Roost

 

[Dr Honda]

Most of your tech questions would be better asked in a Merc Forum.

I'm not sure of the ratios... but I would think the 250 would be a lower ratio... and that will give you more RPM's since the gear box is under driven.

 

[Roost]

Most of your tech questions would be better asked in a Merc Forum.

I'm not sure of the ratios... but I would think the 250 would be a lower ratio... and that will give you more RPM's since the gear box is under driven.

Thanks, You are correct in your thinking about the post belonging in a Merc forum. Funny thing is I was referred here by someone you said this is the place for Merc sport jet guru's.

Does anyone know if there is a more aggressively pitch impeller on the market for the 250?

 

[Dr Honda]

Well... we are pretty good here... but the Merc guys don't do too many mods. If you have troubleshooting, or repair... we can help.

There aren't too many impellers made for the Merc's. If you need more pitch... any jetski impeller shop should be able to add a few degrees. (like Impros)

 

[Igetwet]

The gear ratio that came with the 250 pump is slightly "taller" if that makes sense. I cant remember the exact numbers but the 250 is closer to a 1:1 ratio than the other motors. the 250 has the torque to get out of the hole just as quick without the shorter ratio. If the 250 had the same ratio it would spin right up to the 6000rpm redline in no time, seeing as how the 240 gets to 6000rpm no problem. depending on how quick my motor gets to 6000rpm i'm going to try and find the 250 gears for my 240, for perhaps less hole shot but more top end.

The impellers in all the M2 pumps are the same pitch four blade impeller. I believe Impros has the capabilities to repitch impellers. I might have them do it to my 240 impeller.

The 250 are nice motors but being the 3 liter motor they are considered heavy in the sport jet world. I've for the most part read that the 240 is the best bet because of the weight savings and close to the same power. however i would think the 250 would have more potential to make more power/torque under 6000rpm if someone were to tweek one a bit. And with a 2000lb fishing boat (on the heavier side) it would probable be a better option. i've always been curious to see what could happen if someone did some good tuning to one. I have a 240 for my boat that i had some work done to and should be in that same 260-280 range.