Anyone use dual Blackjack 44's on a 750?

superhondaz50

superhondaz50

Location
Fort Mohave, AZ
As the title says, anyone have this setup? I got a set of BJ 44's for my 750 powered Hurricane Gen 3. Running a Sizzler pipe, milled head and flywheel, hooked to a Solas 144 mag pump with stock SJ big hub impeller. I got jetting from Jetworks, but they are sparse on the convo. Wondering what you guys are running.
 
superhondaz50

superhondaz50

Location
Fort Mohave, AZ
These were the specs given:
2.3 with 115 gram spring 125 low jet and 112.5 mains. lows at 1 1/8 and the highs at 5/8 of a turn.
Want to see if I can get this as close as possible as getting the carbs out of the ski requires pulling the tank, pipe and engine which is a PIA.
 
Roseand

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
superhondaz50 said:
These were the specs given:
2.3 with 115 gram spring 125 low jet and 112.5 mains. lows at 1 1/8 and the highs at 5/8 of a turn.
Want to see if I can get this as close as possible as getting the carbs out of the ski requires pulling the tank, pipe and engine which is a PIA.
Click to expand...
Post some pics, that sounds insane
On Yamaha 701 platforms all you have to do is loosen the bolts that hold the carbs down. I think you need to switch...
 
kevbo

kevbo

Location
dfw
superhondaz50 said:
These were the specs given:
2.3 with 115 gram spring 125 low jet and 112.5 mains. lows at 1 1/8 and the highs at 5/8 of a turn.
Want to see if I can get this as close as possible as getting the carbs out of the ski requires pulling the tank, pipe and engine which is a PIA.
Click to expand...
You can't get meaningful information from another boat unless its an identical one running right next to yours. Become okay with the idea of having to find the best setting all by yourself. Its not difficult just make sure the top screw is slightly rich of best power.
 
superhondaz50

superhondaz50

Location
Fort Mohave, AZ
Roseand said:
Post some pics, that sounds insane
On Yamaha 701 platforms all you have to do is loosen the bolts that hold the carbs down. I think you need to switch...
Click to expand...
It's how far the engine sets back in the engine bay. It's so far back when you look down into it, you can only see one cylinder, looks like a 300sx engine because the rest is hiding under the upper deck. There's no room in there to get your hands in to get to the speed plate. It's a one off Bob Gen 3ish. They had no record of it being made, but said it was prob an employees custom build with a super setback engine.
 
superhondaz50

superhondaz50

Location
Fort Mohave, AZ
kevbo said:
You can't get meaningful information from another boat unless its an identical one running right next to yours. Become okay with the idea of having to find the best setting all by yourself. Its not difficult just make sure the top screw is slightly rich of best power.
Click to expand...
I agree, I've jetted alot of skis, just this one will be a PIA because of what's required to pull the carbs.
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
I run them on a Yamaha Based 820. If Art gave you the settings. I would be shocked if you had to do more than turn a screw just a little bit.

Originally my carbs were set up for a 735.

Low 1 1/8 127.5
High 1/2 107.5
2.0
115G 26psi

So not too far off from what you have. When I went to my DASA, just changed the 107.5 for a 127.5 and it was spot on.
 
Hirschfelt

Hirschfelt

Location
Buffalo, NY
For bottom on a full 750 ski, I have had good success with putting in a 3mm restrictor in the stinger water line. I also add a FCV. This made a huge improvement to the bottom. I would highly suggest doing this prior to tuning the carbs. With the milled head did they adjust the squish? If not I would suggest talking with LPW about having the head set up for 93 octane.
 
superhondaz50

superhondaz50

Location
Fort Mohave, AZ
Hirschfelt said:
For bottom on a full 750 ski, I have had good success with putting in a 3mm restrictor in the stinger water line. I also add a FCV. This made a huge improvement to the bottom. I would highly suggest doing this prior to tuning the carbs. With the milled head did they adjust the squish? If not I would suggest talking with LPW about having the head set up for 93 octane.
Click to expand...
Ya, already have a flow control and restrictor to the stinger. And yes the milled head is setup correctly. It was done by Chris @ Newmiller machine, he is/was the best in the game for these IMO. It's setup for 91 gas and is done beautifully.
 
R

ryanpsd

Location
CA
When I put them on my 550 750 conversion, I told Art what I had and he gave me the following specs:

Low 125 (1-1/8 turns)
High 120 (5/8 turns)
2.3 115G

Every set up is different of course, but for me it definitely seems spot on. I tested those specs, then went up a jet size for comparison and it was down on power, blubbering all over. Dialing it back down I wound up right back where he said it to be. The set I got came off an 1100. When I got them they originally had a 110H jet, so that was the only change I made. Perhaps they could be dialed in more, but they run so incredibly great I'm not going to bother.

I started with a single SBN 44, then 46, and now these. It always ran great, but if that's what you're coming from you're gonna be in for a treat!

I am running a #20 small pin cylinder, Newmiller ported cylinder and cases, pump gas milled head, Zeel with TL, lengthened Westcoast pipe with 2" exhaust, 9/15 Hooker and R&D pump cone.
 
R

ryanpsd

Location
CA
Big Kahuna said:
Why not post here so others can benefit from it?
Click to expand...
How about that timing... you're right, I did not have time to share at the time and should have said "I'll come back to this", or nothing at all until then. I am absolutely all for sharing. :D
 
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