Carburetor (specs) Database: SuperJet and Blaster 1

Have you checked the Throttle Butterflies to see if they are synchronized and fully open at Full Throttle?

Adjust Throttle Cable as needed.

I've seen Pump hooked-up 7600 rpm on a B-Mod Pipe with a different Yamaha based Engine. It's not the Pipe...

A fellow Rider has a Pump Gas Limited 760 with 46 mm Full Spectrums and B-Pipe and is pulling about 7300 rpm and doing about 54 mph...with NO PORTING

Maybe the Engine has an Air Leak?
Yes, carbs are synced and the motor is a fresh build with 18 hrs on it. I did do a leak down test a couple weeks to be certain everything was good
 
Location
dfw
Have you checked the Throttle Butterflies to see if they are synchronized and fully open at Full Throttle?

Adjust Throttle Cable as needed.

I've seen Pump hooked-up 7600 rpm on a B-Mod Pipe with a different Yamaha based Engine. It's not the Pipe...

A fellow Rider has a Pump Gas Limited 760 with 46 mm Full Spectrums and B-Pipe and is pulling about 7300 rpm and doing about 54 mph...with NO PORTING

Maybe the Engine has an Air Leak?
A stock 61x cylinder doesn't have enough exhaust port area for 7000rpm. With a pipe, 62T cylinders run great. They just lose low end response faster than 61x cyls so getting the pump right is more critical.
 
Update: after reinstalling my msd cdi and the stock waterbox my peak rpm increased from 6890 to 6970 at 49.3mph so a step in the right direction but I can tell my jetting is now off, or it was never right to beging with. From the testing I did, my pilot needs to be increased and the main jet seems rich. Anything over a half turn on the high screw and it loads up really bad. I settled at 3/8, didn't want to go in any further.

115 pilot
120 main
2.0ns
95g spring
1-1/4 low screw
3/8 high screw
 
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Are you using a Stock OEM 760 Manifold? Did you block the Crossover Passage?

Are the Choke Butterflies still in the Carbs? Are you Sparkplugs Friend? :p

That High Speed Screw should be around 1+ turns. A Quarter Turn seems Lean...

Find someone who is good at tuning skis to help you.

The Low End Throttle should have the Ski jump out of the Water and snap your Neck back after kneeling and idling for around 10 seconds, then pulling the Throttle hard. Adjust Low Speed Adjuster Screw until you get this response. Do not touch the High Speed Screws until this Step is completed.

Once you have that instant crispy response, then you move on to dialing in the High Speed Screws. The High Speed Adjustment is a matter of finding the Highest RPM in short 100 ft WOT flat water pump-hooked-up sprints, then finish tuning by enriching (opening) the High Speed Adjustment Screw a little (1/8) too achieve a margin of safety.
 
Location
dfw
Tune the top screw using your tach on smooth water. Set it at the rich side of peak rpm. Then adjust the pilots, then recheck the top screws. I suspect your pilots are too small, how does it sound at 1/3 throttle? Each step in pilot size makes a noticeable difference. Mains aren't nearly as critical since you have the top screws to supplement that circuit. It may come to life faster with larger pilots and the top screws set at peak rpm but this can be dangerous for long full throttle runs.
 
Are you using a Stock OEM 760 Manifold? Did you block the Crossover Passage?

Are the Choke Butterflies still in the Carbs? Are you Sparkplugs Friend? :p

That High Speed Screw should be around 1+ turns. A Quarter Turn seems Lean...

Find someone who is good at tuning skis to help you.

The Low End Throttle should have the Ski jump out of the Water and snap your Neck back after kneeling and idling for around 10 seconds, then pulling the Throttle hard. Adjust Low Speed Adjuster Screw until you get this response. Do not touch the High Speed Screws until this Step is completed.

Once you have that instant crispy response, then you move on to dialing in the High Speed Screws. The High Speed Adjustment is a matter of finding the Highest RPM in short 100 ft WOT flat water pump-hooked-up sprints, then finish tuning by enriching (opening) the High Speed Adjustment Screw a little (1/8) too achieve a margin of safety.
I have an aftermarket boysen intake with speed plate and rad valves. Carbs are brand new retail mikuni 44s. Plugs are black/dark brown in color, haven't taken a look at piston wash yet tho. I went thru the progressions of checking my throttle response and I'm definitely lean with either my pop off or pilot jet. When I hold the ski at quarter throttle for 20 sec then stab the throttle it falls on it face then revs up. Turning the low speed screw out helped cover up this hesitation. I think I have a scenario of a lean pilot, rich main but I'm going to make one change at a time and will post the results
 
On your Post #459 you said the Carbs were OEM not Retail!

Brand = Mikuni
Model = OEM
Size = 44mm

OEM means Factory Yamaha Mikuni Carbs. They are different from the Aftermarket Mikuni Carbs.

It's hard to give accurate advice if you give misleading or incomplete info...o_O
 
On your Post #459 you said the Carbs were OEM not Retail!

Brand = Mikuni
Model = OEM
Size = 44mm

OEM means Factory Yamaha Mikuni Carbs. They are different from the Aftermarket Mikuni Carbs.

It's hard to give accurate advice if you give misleading or incomplete info...o_O
Yes indeed. The retail Mikunis flow more fuel and will require different jetting. I have drilled the returns and run a 80 main jet as thr restrictor on my carbs
 
On your Post #459 you said the Carbs were OEM not Retail!

Brand = Mikuni
Model = OEM
Size = 44mm

OEM means Factory Yamaha Mikuni Carbs. They are different from the Aftermarket Mikuni Carbs.

It's hard to give accurate advice if you give misleading or incomplete info...o_O

Ohh man, I totally screwed up on that one. I got them switched around with reading this thread 4 times over
 
Location
dfw
On your Post #459 you said the Carbs were OEM not Retail!

Brand = Mikuni
Model = OEM
Size = 44mm

OEM means Factory Yamaha Mikuni Carbs. They are different from the Aftermarket Mikuni Carbs.

It's hard to give accurate advice if you give misleading or incomplete info...o_O
The most accurate advise on jetting? Whats in my carbs probably won't work in yours. Learn how to tune!
 

waxhead

wannabe backflipper
Location
gold coast
On your Post #459 you said the Carbs were OEM not Retail!

Brand = Mikuni
Model = OEM
Size = 44mm

OEM means Factory Yamaha Mikuni Carbs. They are different from the Aftermarket Mikuni Carbs.

It's hard to give accurate advice if you give misleading or incomplete info...o_O
yeah any advice I gave you on these is incorrect now
 
This is what worked perfectly and added power top and bottom over a single Novi 48 on a 96 superjet ported to the moon. Threw on oem duals from a 760 and jetted with this. Stock intake, carbs, airbox with carbon tech reeds. B pipe
 

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