Other What pump/prop are you running with a JM781?

twisterad3

twisterad3

I purchased a used JM781 over winter, along with dual 38's. I'm really digging the power of the ski... I'm wondering what pump/prop/intake grates you guys are running with this package?

Backstory on this question:
I recently purchased a Hurricane Industries Apex (which is basically a modified superjet). Whenever I'm chasing a surf boat and jump a wave, I'm struggling to get hook up after a deeper water landing. I can pull the go-lever, but I don't really go anywhere till I get off the ski and get it flat.

My current set up:
- JM781
- Dual 38's
- Mag Pump stator
- 9/15 Hooker (from old superjet)
- No intake grate (dude who owned the Apex before me RTV'd the intake holes, I need to drill it out.

I'm wondering if this is more of an intake grate issue? Too low pitch impeller issue? 144 vs a 155 issue?

All my previous experience has been on a 90 Superjet with a 735, running this same pump. I don't think I struggled as much to get out of the hole, but I also don't think I was jumping quite as high... so as a result, I wasn't sinking the ski as much on the landing...
 
Quinc

Quinc

Buy a Superjet
Location
California
I have a 771cc engine with all the fixings in my gen3 bob. Went from a 144 mag with 9.5/15.5 hooker to a 148 torrent and the difference was night and day. If buying new I would go with the torrent 150.
 
waksk8

waksk8

Site Supporter
Location
Jacksonville TX
I had the same issue on my Chan. I used my SN seal that goes between the pump and shoe, and on the new hull the pump didn't fit as tight against the pump shoe. I figured this out by taking a flash light and shining it from inside my pump, and you could see light coming through. Once I put a new seal in it made a world of difference.
 
twisterad3

twisterad3

@Quinc - That good to know. I've been looking at OE 155's... Haven't pulled the trigger on anything yet. My buddy's 155 seems to compliment his Carve ski very nice with a JM735 in it...

@Big Kahuna - Yea. I was kinda thinking the same thing. I have 3 grates to choose from in the mean time... Works 205, Jet dynamics (with a big @$$ scoop), and a Solas grate... I sold my 10/16 a while back when I didn't think I'd be in the bigger bore game... Regretting that right now!

@waksk8 - I trimmed the seal, and it's literally about as tight as it can go.. It took a team to get the pump bolts in place... No light is coming through that bad boy when we checked! haha.
 
twisterad3

twisterad3

@Quinc - That's a very fair point. I'm no opposed to a 148. I would 100x go with a 148 over a 155 to avoid the glass work! I have enough glass work to go around with my SN tray!
 
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