dual 44s on 701

[waxhead]

Seadoo used dual 46's on the 946 motor as well. No idea if those work on Yami's or not.
If I wanted bigger carbs the biggest I'd go is the oem dual 44's from Yamaha until I got into aftermarket engines. Once you get some real power going dual 46's would be my choice until you need the big boy aftermarkets.

you are right on the 46. That was an i-series carburetor

 

[kevbo]

I-series carbs have a much larger choke area in relation to the throttle plate. They need much larger main jets than an SBN. A restrictive flame arrestor may be required to make an I-46 work on a small engine.

 

[fastgtfairlane]

alright so my superjet is running with the 44s. also talked to TNT Tim about jetting for the 44s because im running a tnt SS chamber on this engine. he recommended 117.5 pilots, 120 mains, 2.0 n/s with 95g spring. ended up with 20psi popoff with the 2.0 and the 95g spring. im about 1.5 turns on the lows and 1 turn out on the highs. i also filled the crossover tube on the manifold and am currently running the single pulse line teed to both carbs with both inlets and outlets on the carbs teed to one supply line. runs pretty solid and really havent had to touch a screw. its definitely a little rich but it fires right up and doesnt have any hesitation or bog.

 

[Quinc]

I find Tim's recommendations to be on the richer side. For more freestyle/low end power I would try 120 pilots 110 mains.

 

[fastgtfairlane]

he might have done that to make sure i didnt blow it up haha. he did say it could be a range of a few jets depending on where im located. he did say could be as low as 110 on the main when i messaged him. it ran pretty strong as is but i think i might play around with it.

 

[kevbo]

Keep in mind that filling the crossover allows for smaller jets. You need to spend some time and power tune the top screws to find out what "YOUR" main jet requirements are. They are seldom what someone far away thinks it should be!

 

[fastgtfairlane]

i agree. it runs really good as is but definitely has more in it. i just swapped impellers as the one that came with the pump was too tall. i added up to 5mm shims to the impeller and got it running better. swapped it out for a 7/14 and its night and day better. 148 5mm setback mag pump. now i can play with the carbs a little. i dont have a 110 main at the moment but i do have a 115. so maybe ill try the 120 pilots and 115 mains for now and see how it runs.

 

[waxhead]

i agree. it runs really good as is but definitely has more in it. i just swapped impellers as the one that came with the pump was too tall. i added up to 5mm shims to the impeller and got it running better. swapped it out for a 7/14 and its night and day better. 148 5mm setback mag pump. now i can play with the carbs a little. i dont have a 110 main at the moment but i do have a 115. so maybe ill try the 120 pilots and 115 mains for now and see how it runs.

i would try 125 low and 115 highs. On a b-pipe with 44 I like my total jetting to add up to about 140
my own ski runs 130 lows and 110 highs.
But i have a zeeltronic with a heap of advance down low

 

[bored&stroked]

I just got a set of oem 44's and manifold from a 760 to put on my SN. Sure its been bored and ported but this is great info to reference since I suck at carb tuning, glad it was brought back to the top.

 

[Quinc]

i would try 125 low and 115 highs. On a b-pipe with 44 I like my total jetting to add up to about 140
my own ski runs 130 lows and 110 highs.
But i have a zeeltronic with a heap of advance down low

@Callison62 write this down for when you get new carbs.

 

[fastgtfairlane]

i would try 125 low and 115 highs. On a b-pipe with 44 I like my total jetting to add up to about 140
my own ski runs 130 lows and 110 highs.
But i have a zeeltronic with a heap of advance down low

What was your popoff? I'm running a 2.0 n/s with 95 g springs 25psi according to the chart but I measured 20psi with that combo. I'm also running a stock 62t cylinder instead of a 61x cylinder. Just slightly less snappy off the bottom but pulls harder from 1/4 throttle on.

Also I'm curious if the chamber I'm running would change the tune vs a regular superjet chamber. It sounds very different than any other ski in my group and all are running bpipes. Mine is definitely quieter. I'm running a jet maniac box. The centerbleed changes the sound entirely

 

[waxhead]

20 psi is fine. yes it changes it a little but nothing a quick tweak on the screws will not fix

 

[Joell_Leone]

Keep the 38's. You'll have better low end response and throttle control.

Yeah, that's what I have on mine and I like them better.

 

[fastgtfairlane]

Keep in mind that filling the crossover allows for smaller jets.

tim recommended leaving the crossover tube open but i had already filled it. he said it will help with low end response leaving it open. i did that before ever trying it out so im not sure how much difference it makes. can you shed some light on that?

 

[waxhead]

It will be fine with the cross over blocked, dont worry about it. my one is blocked and no one who has ridden it has complained about lack of throttle response

 

[fastgtfairlane]

yeah mine has good throttle response i was just curious if anyone tested it back to back to see if they noticed any difference.

 

[kevbo]

Crossover open provides a steadier pull on the pilot jets. The net effect is it allows a little better response from a leaner 1/4 throttle setting. No crossover usually requires a little more fourcycling at 1/4 throttle for best response. The confusing part is in the fact that no crossover can actually run richer with smaller jets. This is why you have to listen to your engine and pay attention to response. Too rich will work but with uneccessary chugging and fuel consumption. Too lean will sound clean but have a dead spot when you tug the throttle. I usually have to change the pilots 2-3 times to find a setting that is as clean as possible with good response from 1/4 throttle. Pilots are very sensitive so one size makes a very noticeable difference. Power tuning the main is simply gauging the pull at full throttle after the engine is fully spooled up. A tachometer is really handy for this because its hard to feel a 20-50 rpm difference. Remember the top screw is in parallel with the main jet and acts as a fine tuning device. One turn out allows you to alter approximately 10 jet numbers either side of what is installed. If the main is correctly sized, you should be able to make it run worse by opening or closing the top screw.

 

[fastgtfairlane]

More updates. Was out labor day weekend with some wakeboard boats throwing a v wake as well as surf wake for us. Tried my first ever backie attempts with the superjet and for myself Haha. Tried 4 times, 3rd time almost nosed it in. 4th time feet came out of the holds with the ski landing upside down and getting water in the engine in the process. Towing back ended up sinking the ski as I have a one way valve instead of a bilge pump . Getting it running again I accidentally had it backfire and broke a new carbon reed petal and bending a butterfly on the throttle shaft. With all of that, I replaced throttle shafts and new reeds will be here tomorrow. Also broke down and bought a ada head as well as picked up a zeel cdi to eventually install once I get the exhaust bracket figured out. Also changed jetting to 120 pilots and 115 mains. We'll see how it runs this weekend.

 

[fastgtfairlane]

.

 

[Quinc]

@squiggy_bum