i have a 96 superjet with duel 44s and cant seem to get the punch it should have. ski is a 701 big bore with duel 44s from team scream, some light rec porting, ada girddle kit with 175 compression , MSD enhanser, factory B pipe (mod chamber). if anyone can help me out with the carbs and what jets to run, highs and lows and how many turns on the screws i need to do that would be great, thanks
Super Jet carb issues
- Thread starter briank
- Start date
just the carbs where done by team scream which i bought them off of someone on the x that they had done by team scream. its a fresh build but the motor and everything else seems to be fine. to me it just seems like its a fuel issue, the ski rips like crazy but seems to lack a bit on the bottom end. theres no hesitations or anything like that or bogging... when i hit the throttle it hits ok, then when i hit it on mid throttle then the bottom end is there. seems like the bottom end is at mid throttle where it screws me up for jumps. somethings missin and dont know what
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Right off the bottom is your pop off and that sounds good. Around 1/3 to 1/2 throttle is when the high speed jet kicks in. Since both of the very bottom and the very top sound like they're good, I'm guessing your low jet is off. I'm betting your low speed jet is too small. Does it get ever so slightly better when you richen the low speed circuit? If so, try going up 1 or 2 jet sized on the low.
SUPERTUNE
Race Gas Rules
- Location
- Clearwater Fl.
How long has it been since the carbs have been freshened up with a Mikuni kits and new needle valves?
How much porting was done? Who did it? How much is the exhaust port raised? What prop and how is the pump setup?
What size domes on what size bore?
With aftermarket Mikuni carbs you can run more compression than 175, 190 min. for freestyle/freeride.
How is you waterlines setup? Are you running dual cooling and a Jetworks FCV on the stinger?
Have you ever checked/set your timing with a timing light or just running stock settings? Are you running the stock 62T flywheel?
What are you running for intake manifold and reed setup?
What size is the exhaust outlet on your 'B' pipe?
What screw settings on the headpipe adjusters?
Just keep in mind sometimes it's not about just throwing modifications at it, it's about following a proven recipe to achieve the results you need for your application.
Screw adjusters should be around 1 1/4 to 1 1/2 turn out on the low and about 3/4 turn out on the high on X Scream prepared carbs.
The cylinders had light rec porting by someone here on the x. The motor has 84mm pistons w/ 35 domes. It has dual cooling and running a FCV. It's a stock intake with the crossover filled, OEM Reed cages w Carbon Tech Reeds. Brand new modified b pipe and FP Waterbox, MSD Enhancer and stock flywheel. The carbs (AM dual 44's) were from X Scream and I purchased them from someone on the X. They are currently setup as follows: 132.5 Top, 125 Bottom, 2.0 needle valves, 95 gram spring.
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Race Gas Rules
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- Clearwater Fl.
Are the return bleeds drilled out in the carbs and do you have a brass T with the jet in it for the return lines?
Jetting sounds like Lamey 7 port cylinder jetting, not anything I would run in a stock 5 port cylinder...I would have to go way back in my jetting book to see who I might have put that jetting in for.
On another note, I did a quick compression ratio figuring for a 84mm bore, 68mm stock stroke engine with 35 cc domes, I would say it's pretty aggressive porting if you think you got a good compression gauge reading @ 170 lbs.
You should have more than that, maybe a bad gauge or check? OR like I said pretty aggressive porting. Your going to maybe need a better programmable ignition like a MSD TL, Flame TL or EPIC CDI to get any hard snap off the bottom. You never did state what prop and pump setup is, that will easily kill off the bottom with a heavy ported engine.
the prop is a 10/16 hooker in a stock sj pump... and i don have brass fittings, but what do u mean by the jet in it??? i scrwed up, the domes are 37cc domes, thats why im getting 170-175lbs of comp. but everything else i stated is correct. sorry about the mix up on the domes. what do u think about that, does that change things a bit??? i know the snap is there i just need to find it.
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SUPERTUNE
Race Gas Rules
- Location
- Clearwater Fl.
The first thing I asked was...IS THE RETURN BLEEDS DRILLED OUT IN THE CARBS? You didn't answer.
When the return bleeds are drilled out you then need to use a external bleed, this is done by using a brass 'T' fitting on the fuel return lines, with a small main jet tapped and screwed into the end that goes back to the gas tank.
This will regulate the fuel pressure the carb will have on the jets.
If you don't have this restrictor then the carbs will have hardly any fuel pressure at and off idle and not have very good bottom end or crisp throttle response.
SUPERTUNE
Race Gas Rules
- Location
- Clearwater Fl.
Have you measured the pump nozzle size and know for sure it is the stock size? Same with the pump cone?
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
Chuckie, what size jet do you recommend. I have a jet screwed into the nipple on the tank. But I have run your carbs for years without a jet in there also.
- Location
- pine beach, nj
I believe he is running a Restrictor T with a 60 in it.