why won't my ski idle?

[Quinc]

She starts with ease, cant remember the last time i used the primer. runs great pulls hard off the bottom and runs strong on top. I can hold the throttle in any position and go wide open. My problem is she will not idle in the water for more then a few seconds.

I think my jetting is pretty high so not sure if I should go higher or change pop off?


61x 753cc
190 psi
Msd enhancer
Coffman sizzler
RN waterbox
Run 94 octane

46mm sbn
Carbon tech reeds
Tau Ceti flame arrestor
Intake mani opened to match carb
No choke


Pop off 24psi
Pilot 130 - 3.5 turns out
Main 155 - 3.5 turns out

Can go as far as 4 turns out.

I started with a 125 pilot and 147.5 main and there has been no change in the idle going up in jets. But she seems to runs awesomer with each jet change...

 

[Vumad]

Have you tried turning the idle up?

Buy a tach. Hardline is about $30. I like a very gentle idle, so I would prefer it to be about 1200 RPM. My superjet runs great but will not idle below 1400 RPM. It's pretty happy at 1600 RPM, but even then, it will occasionally stall under a load.

My X2 on the other hand will idle perfectly and indefinitely at 1000 RPM, and it's tuned like poop compared to my superjet. Just the nature of the beast I suppose.

Edit: If it keeps running better as you go richer, you should probably keep going richer until it runs poorly, then go back. Always safer that way. Also, 4 turns out on the screw is really outside of it's effective range. You likely wont see any changes between 3.5 and 4 turns out because wide open is wide open.

 

[Quinc]

I have a tiny tach and for the few seconds she idles it is right around 1150-1250. However, the tiny tach doesn't seem to play well with the msd enhancer and starts bouncing from 0 - 7k . I can try going up to 1400-1600rpm but damn that seems fast.

 

[Harbor]

Now that you mention it Quinc mine does the same thing, idle a few seconds then quit, restarts fine, without input from the throttle lever it quits after a couple seconds when in the water, on the trailer it will almost stay idling, I don't trust it during flushing though so I manage it from the throttle lever.

I prefer the lower idle though and control it with the throttle lever, at times I'll turn up the idle speed if I don't want it staling.

Maybe 1300 or 1350 instead.

 

[Vumad]

1600 is fast, but that's how high the motor wants to be to keep running in all conditions. I recall that when I was first putting my limited together, jetmaniac said to set the idle at 1200, but that I may want it higher to keep it running at all times.

I Had a msd and no issues with my hardline. My msd failed so I don't have it anymore.

 

[NVJAY775]

3 turns out on main / high end is maxed. One turn out on pilot / low end is maxed. The low end is debatable somewhat though. Can't remember the reason why (I've heard it a couple times now and always forget) but Ed at FastCarbs said it somewhere, but it may be for a some specific situation? Sounds to me that your bottom end is a bit fat though. Just a guess.

Have you read over the Mukuni manual and tuning? It definitely helps you understand and troubleshoot all the circuits of the carb/s. Skip down to page 13 tuning. Then hit the end for troubleshooting as well. I keep a copy with me always. http://www.mikuni.com/pdf/sbn_manual.pdf

 

[speedysprocket]

1 1/2 to 2 turns out on the low screw is about it. Don't want to go much over 1 turn on the high speed screw.
Plus, jets aren't going to mess with your idle. That's primarily your idle stop screw and low speed screw. If your pop off is too too far off, that could mess with it but 24 psi sounds fine plus the fact that it restarts easily.
Does it idle out of the water fine?

 

[Vumad]

I agree your jetting doesn't much affect your idle. We changed like 5 jet sizes with no changes on the idle on my x2. Now being lean on the low speed did let it start to run away on the trailer, but unloaded is different.