Help carb issue I think

[Mike Grafas]

Hey guys

All stock superjet 701 dual 38s with a raider motor in it

I started having a low end bog so I rebuilt the carbs and set everything to factory spec

Pop off 55psi
Low adjusters 1 turn out
High adjuster front 1 1/4
High adjusters rear 1 1/2

So I start the ski and it idles great but when I go slow on my knees it wants to run out of fuel it seems like, if I start blipping the throttle it will get worse and worse until it stalls

It fires right back up though

Weird thing is if I get past the low jet and into the high it runs great

I've adjusted low speed screws from half turn out all the way to 2 1/2 turns out with no change

I already pulled carbs apart twice, there is nothing in the low jet

I can't say it would be fuel selector because high speed is great

One way valve is new as well

 

[Barbieri972]

Is it hard starting in the water?

 

[Big Kahuna]

Remove flame arrestor and crank the ski. is there alot of gas dribbling out in the carbs? Needle and seats may be leaking.

 

[Mike Grafas]

Already checked needle and seats during rebuild, they needed to be replaced so I replaced them

It is not starting in water, fires right up barely a crank

 

[Vortex]

Pop off might be too high. What flame arrestor are u running

 

[Mike Grafas]

Stock flame arrestors, 55psi is stock. Had it at 40 and did the same thing it's doing now

 

[Vortex]

Hmm. It's possible you have a bad plug, plug wire, or other electrical component acting up

 

[Mike Grafas]

Hmm. It's possible you have a bad plug, plug wire, or other electrical component acting up

Runs fine on top end, is running out of fuel on low end

Once carbs fill with fuel it's ok again
If I make my way to high end it will run all day

 

[Vortex]

Runs fine on top end, is running out of fuel on low end

Once carbs fill with fuel it's ok again
If I make my way to high end it will run all day

If you nail it from idle to wide open how does it act? You may simply have not enough low speed jet. Or you need to lower the pop off more than you have. They work together to transition to the high jet.

 

[Mike Grafas]

If you nail it from idle to wide open how does it act? You may simply have not enough low speed jet. Or you need to lower the pop off more than you have. They work together to transition to the high jet.

Definitely not low speed jet, it ran great when I first got it
Nailing it from idle to wot is fine if I first start it but if I stay on low speed for a while then nail it it'll stall out

Pop off was at 40 but 55 is stock so I brought back to stock settings

I rebuilt the carbs with winderosa kits because that's what my guy had but I have mikuni kits coming in so maybe just a fault in the gaskets?

 

[Vumad]

I have stock carbs, 1 screen out, 42psi.

My ski likes to idle about 1400rpm if it's going to do so and never stall. It will idle at 1200 but will eventually stall. Not sure if you have a tach but the yamahas seem to like a little higher idle.

 

[Mike Grafas]

I have stock carbs, 1 screen out, 42psi.

My ski likes to idle about 1400rpm if it's going to do so and never stall. It will idle at 1200 but will eventually stall. Not sure if you have a tach but the yamahas seem to like a little higher idle.

Idle is up there, idles a little higher than what it used to so it doesn't want to stall, will idle no problem

 

[Vortex]

From what you said it sounds like youre lean on the low speed circuits

 

[Mike Grafas]

From what you said it sounds like youre lean on the low speed circuits

So I took it to the ramp today, doing same thing

Is it possible my fuel lines are bad?
Weird because once I get to high jet it runs fine, is it possible there's a blockage and higher rpms is able to pull fuel past blockage (running lean obviously)

 

[Mike Grafas]

Rebuilt carbs with mikuni kits, same problem

Could this be a slight exhaust leak? By me blipping the throttle it slowly starts to die out

I plan on checking today but now that I think of it I never ran it with the hood off to see

 

[Mike Grafas]

Nope, no visible smoke

But running on land plugs were WET

And last night and testing in water they looked wet as well

 

[Vortex]

Wet plugs would indicate electrical issue. Weak or intermittent spark. Such issues are known to only happen in certain rpm ranges and not in others. Coil would be the first thing I'd look at. A new OEM coil is not a bad thing to have if yours is old.

 

[Mike Grafas]

Wet plugs would indicate electrical issue. Weak or intermittent spark. Such issues are known to only happen in certain rpm ranges and not in others. Coil would be the first thing I'd look at. A new OEM coil is not a bad thing to have if yours is old.

Have a Msd coil in it, was in it when I bought it

I bought an OEM coil to replace but haven't done it yet

But like I said if I keep blipping throttle it will want to stall getting worse and worse

Could it be that I am too rich?

I never show signs of loaded up and trying to clear out, just less and less throttle response till she stalls

 

[Vortex]

Have a Msd coil in it, was in it when I bought it

I bought an OEM coil to replace but haven't done it yet

But like I said if I keep blipping throttle it will want to stall getting worse and worse

Could it be that I am too rich?

I never show signs of loaded up and trying to clear out, just less and less throttle response till she stalls

Yes it could be rich a 1.5 needle flows the most fuel

 

[Mike Grafas]

So I guess originally it was my first rebuild kit I used(winderosa)

After I put my mikuni kits in and turned screws out 2 1/2 turns she was good, had to raise idle a little

2 1/2 with winderosa was doing same thing, but now she wants to take off

After blipping throttle like crazy trying to simulate the problem it wouldn't do it

2 1/2 seems like a lot but maybe it's because I've got 67.5 pilots?