Carburetor (specs) Database: SuperJet and Blaster 1

Joined
Feb 19, 2013
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4,256
Location
Chico California
Basically your prop is peaked at 3/4 throttle. could pitch up a bit. It is pushing all it can.
Interesting. I run a 10/16 hooker in my a/m ski with the same pipe and dual 44's and she just keeps pulling. I will try a different/ large hub impeller next. Thanks!

*currently running Solas 14.5/18
 
Joined
Dec 22, 2006
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127
Location
MotorCity
Finally got around to tuning my boat in flat water and noticed that I have no difference in power from 3/4 - full throttle. Any ideas?

754cc
ported cylinder
blue printed pump w/ Solas 14.5/18
stock 38's no choke, OP flame arrestors
80 low
135 high
95g spring, 2.0 needle seat

TNT piped tuned to sizzling hot chamber, 2mm stinger hole, headpipe is cool/warm to touch.


*Ski is like a rocket going from 0-3/4 throttle though. :)
your going rich(?) did you turn in the screws and see if RPM gains? my experience with good ported setups jetting numbers are leaner than 80/135 because of the increased efficiency (draw or velocity) of the system. Tune on peak RPM

Example: Same motor
58 mph with 38's could be 70/130
58 mph with 48's could be 140/140

48's will get you their faster but require more jet because of intake velocity.
 

Tyler Zane

Open Your Eyes
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Joined
Jun 2, 2010
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492
Location
Panama City Beach, FL
Square nose, -3

Brand = mikuni
Model = retail
Size = 44
Quantity = 2
Main Jet = 132.5
Pilot Jet = 120
Needle/Seat = 2.0
Spring = 80
Pilot screw =1.5
Main Screw = 1.5
- - - - - -
Gas Octane = 93
Altitude = sea level
Main type of riding = freeride
Would it pass the 10 second WOT test = always wot
Powerband = mid to high
Motor type/setup = ada head 35cc domes, 701 62t cylinder, 62t cases, oem intake, carbon tech reeds, b pipe mod, (All screws closed, spray bar in head pipe), msd enhancer, stock flame arrestors with 2 screens, 148 mag, 9/15 solas.

Ski runs absolutely great. Never skips a beat, pops right off and will idle across the lake. Best running ski I have tuned from scratch and I'm proud of it.
 
Joined
Feb 19, 2013
Likes
4,256
Location
Chico California
your going rich(?) did you turn in the screws and see if RPM gains? my experience with good ported setups jetting numbers are leaner than 80/135 because of the increased efficiency (draw or velocity) of the system. Tune on peak RPM

Example: Same motor
58 mph with 38's could be 70/130
58 mph with 48's could be 140/140

48's will get you their faster but require more jet because of intake velocity.
Good to know, I was under the assumption that larger carbs/more air would increase mph and rpms. I will take out the tiny tach and gps this weekend and play with the screw settings/jetting.
 

Big Kahuna

Administrator
Joined
Jan 14, 2006
Likes
6,529
Location
Tuscaloosa, AL
Square nose, -3

Brand = mikuni
Model = retail
Size = 44
Quantity = 2
Main Jet = 132.5
Pilot Jet = 120
Needle/Seat = 2.0
Spring = 80
Pilot screw =1.5
Main Screw = 1.5
- - - - - -
Gas Octane = 93
Altitude = sea level
Main type of riding = freeride
Would it pass the 10 second WOT test = always wot
Powerband = mid to high
Motor type/setup = ada head 35cc domes, 701 62t cylinder, 62t cases, oem intake, carbon tech reeds, b pipe mod, (All screws closed, spray bar in head pipe), msd enhancer, stock flame arrestors with 2 screens, 148 mag, 9/15 solas.

Ski runs absolutely great. Never skips a beat, pops right off and will idle across the lake. Best running ski I have tuned from scratch and I'm proud of it.
These my old carbs?
 
Joined
Feb 19, 2013
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Location
Chico California
your going rich(?) did you turn in the screws and see if RPM gains? my experience with good ported setups jetting numbers are leaner than 80/135 because of the increased efficiency (draw or velocity) of the system. Tune on peak RPM

Example: Same motor
58 mph with 38's could be 70/130
58 mph with 48's could be 140/140

48's will get you their faster but require more jet because of intake velocity.
Forgot the tach, gps and gopro..
I had a bad one way valve. Replaced it and opened up the screws half turn each. Maybe a slight difference in 3/4-full now. For top speed, I was at the bouys working on my 180 stabs and two sparks took off in a race with the riders fully tucked. By the time I turned around they had about a 200ft head start. I ended up catching and passing them both. :)
 
Joined
Feb 4, 2016
Likes
4
Location
Michigan
Ran ok with old jetting, rebuilt carb and updated jetting try to help... the setup is below still struggling

Square Nose

Brand = Mikuni
Model = Retail
Size = 44
Quantity = 1
Main = 115 to 120
Pilot = 155 to 150
Needle/Seat = 2.0 before and after
Spring = black/dark to 95g
Pilot Screw = 1.125 to ___ . Been 1 to 3.5 will no better nor worse
Main Screw = 1 to ____. Trying to dial the pilot first.
Pop Off = was ____ to now 20psi. did not check before rebuild.
Arrestor: none previously (owner never ran one) to now tau ceti tornado with jacket
-----

Gas Octance = 93
Altitude =sea level
Main Riding = rec level, local lakes
WOT test = probably pass but havent tried
Powerband = standard - no porting
Motor type/setup: 701 61X cyl and cases, wet jet intake, boysen fiberglass reeds, 10/18 scat trak prop, factory b pipe (screws unknown-left from previous owner), stock yami cdi, 2" tau ceti arrestor

Idles perfect. Brought low speed out from 1 to 3.5 with slight improvement but still not crisp. Plugs were light brown/grey (leaner side-imo) but increased in pilot size from rebuild so confused as to why its still not boggy... im attempting to go way rich and dial back the pilot. Thoughts?

Added an additional gasket to the carb on the rebuild blue #2 in the pic. wondering if that could be giving me issues. It did not come out of the carb but the picture showed it so I put it in...? Could a flipped check valve disc be giving me these tunning issues?
Mikuni Carb Rebuild Question.jpg
 
Joined
Feb 4, 2016
Likes
4
Location
Michigan
@Cody Sampson Try 125Pilot jet and 150 Main jet with 24PSI pop off.
went to a 21 PSI popoff and ended up with a 130 Pilot Jet and a 160 Main jet.. 2 turns out on both screws. Seems excessive but the ski hasnt had the rich bog yet. Ran fine yesterday afternoon. Could there be an air leak causing the large jet sizes or do some engines just love fuel?
 
Joined
Apr 19, 2009
Likes
4
Location
canada
Need Help
2 x 44mm
760cc bore 85mm
porting cases and cylinders more a 6mm crankshaft,
Stock ignition with MSD Enhancer
do you have a starting jetting to advise me
Thank
 

Roseand

Ready to RIP
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Dec 31, 2012
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Location
Wisconsin
Carbs off of an Oem 760 or retail sbns? Basically are there 3 or 4 transition holes in the throat of the carb?
I run Oem 760s 44s with a 5mil stroker 84mm bore/ported 760 cylinder and cases and 117.5 pilot and 122.5 main is the recommended jetting.

Sent from my SM-G920V using Tapatalk
 
Joined
Jul 20, 2016
Likes
20
Location
minnesota
looking for another carb suggestion/help from some of you guys.

so i just bought a set of fresh dasa 48mm carbs, which i plan to swap out my 44 blackjacks with and run until i upgrade my motor this winter, or if i like what i get out of my 780 w/ the 48s maybe just stick with this motor and the new carbs.

so i've found some settings for full spec 48mm carbs on a setup very similar to mine, but none for dasa 48mm carbs and close to my setup.

i set up the 48s on the bench as follows for what info i was able to find.

125 mains - i think i need to be 135?
125 pilots
2.0 n/s
95g spring
18-19psi pop off.

my current ski setup is -

781 jet maniac 180psi motor
Dasa billiet intake
Vf3 reeds
44 blackjacks (don’t remember jetting)
pro k flame arrestors
B pipe
Charging electronics with kawi coil, and msd enhancer
Light weight FW
148mm solas mag pump
8 or 9/13 or 14 skat prop
Stubby cone
Nozzle bored to 89mm
Steering bored to 91.5
 

Zero Client

Blowsioning my money!
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Joined
Sep 27, 2013
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148
Location
Marietta, GA
Finally got the time to ride and tune this ski out. I only ran it a few hours total this summer and so it took time and a couple testers awhile.

Ski has consumed about 40 gallons of fuel, but also ski consumes about 4 gallons every hour (So, its got only about 10 hours on the motor) - Most of which was at Southern Fried Freeride this past month.

Note - this is the first ski I've ever tuned which ended up with MATCHED jetting across both High/Low and both carbs. Plugs are coming out nice and black. First throttle after a long idle has only a slight load (if any) to blow out, once the pipe comes up to temperature (3/8 turn on the pipe's top screw only) after about 3~4 throttle hits its game on. The ski absolutely rips, even when the pipe is cold :)

Brand = Dasa
Size = 48mm
Quantity = 2
Main Jet = 135
Pilot Jet = 135
Needle/Seat/Spring/Popoff = 19PSI
Pilot screw = 1&1/8
Main Screw = 3/4

Another note on the carbs - Restrictive returns drilled out and a common collector was used with a 60 main jet as the restrictor
- - - - - -
Gas Octane = VP Racing VP110 Race fuel (Also runs fine with VP C12)
Altitude = 800ft
Main type of riding = Carbon RCW Havoc. Confirmed Flat water black-flipper
Would it pass the 10 second WOT test = YES
Powerband = Mid&Top, but with the lightweight ski its a bottom jumper too
Motor type/setup = Billet Dasa 850ss PV motor bored 1mm over, cylinder ported for mid/top end, dropped cylinder - no base gasket using Threebond 1217, Crank built by Competative/ADR, 39cc domes with custom 20thou squish relief (48thou). pushing 220psi compression (240psi with PV Un-Lifted), Skat 155 pump 9/14 prop, Dasa intake, vForce reeds, MSD enhancer, Limited B-Pipe, JM waterbox, Dual 1/2" cooling, Water overboard from 4 spots on the cylinder and pipe (5 pissers total).
 
Last edited:
Joined
Jul 20, 2016
Likes
20
Location
minnesota
kyle got back to me on what he thinks I should try based on my above setup

"This should be a overall good starting point 135P, 125M, 2.5N&S, 115gm Spring"

for anyone else needing the info.
 

Zero Client

Blowsioning my money!
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Location
Marietta, GA
Chadly, If your ski's power drops flat after the 2nd~4th throttle wack then increase your main jet right away. On my Dasa 48 carbs I found; they come on the main at a fairly low throttle position - like 1/3 throttle. Wack a few times and the motor runs the mixture dry pretty quickly and you'll feel the engine stumble or even fall on its face.
 
Last edited:
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