Super Jet 61x jetting

[Dohc4valve250]

I got a 61x with jetting issues. I have an "Ada" head coffmans pipe and it's ported. The jetting in it now is a 120 pilot 142.5 main and a 1.5 seat. It idles fine but when u hit the throttle it Boggs right out and dies. Any suggestions????

 

[ryan]

bigger low speed jet for starters. what spring? what compression ? high low screws where they at?

 

[Dohc4valve250]

bigger low speed jet for starters. what spring? what compression ? high low screws where they at?

No idea what size spring. What do u suggest for a low speed jet? 150 compression. 1 1/4 high 1 1/2 low. I was thinking a pinched fuel line or clogged fuel filter however neither is the issue. Runs with choke on.

 

[DirtyJ]

Find out what your pop-off is first, thats key. Your adjustments dont sound to far off.
I would try a 122.5 or 125 p and a lower main jet 137.5 or so.

 

[whitca]

According to the mikuni manual off idle response is controlled by popoff up to 1/4 throttle where pilot circuit comes on. Check what spring you have. If its running with the choke on its too lean. Its getting more fuel with the choke and when you open it it leans out with the increase of air to the mix. What carb(s) just for reference?

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[Dohc4valve250]

According to the mikuni manual off idle response is controlled by popoff up to 1/4 throttle where pilot circuit comes on. Check what spring you have. If its running with the choke on its too lean. Its getting more fuel with the choke and when you open it it leans out with the increase of air to the mix. What carb(s) just for reference?

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Standard stock 38 carb. What spring should I use then? It has the gold spring in it now

 

[DirtyJ]

Standard stock 38 carb. What spring should I use then? It has the gold spring in it now

Is it a 38 or a 44? Stock carb on a set of 61x cases would be a 44.

 

[Dohc4valve250]

Then it's a 44

 

[whitca]

Popoff is too high. Gold spring (115 gram) with a 1.5 needle and seat puts you at or around 55psi. Try a less stiff spring or bigger needle and seat. Or you can try cutting rings off your gold spring and see if it improves, just start small if you decide to try this. Before you do any of this try going bigger on the pilot jet and see if it improves. This can sometimes compensate for too much popoff pressure.

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[Midlake Crisis]

Make sure your internal and external fuel filters are clean and clear before you start messing around with adjustments.
I have had internal filters clog on 2 skis.

 

[garretonufer]

next time you ride, take your FA off. see how it runs, if it runs better than you know you're too rich, if runs worse you know you're too lean.

not familiar with coffmans pipes but i know the factory pipe says to run a 145 main.

from what i've read, your idle is controlled by low speed screw, 0-1/4 throttle controlled by low speed jet. pop off pressure (N/S & Spring) controls transition from low speed jet to high speed jet. the rest is controlled by high speed screw and jet.

if your ski idles than i'd say your low speed jet and screw are fine. i'd toy with your high speed screw and pop off pressure.
if you need to turn out your high speed screw 3 turns, you need to increase the jet size.

I hope this gives you a starting point.

 

[2XLR8]

Have you tried turning out the low further out ? If not I would try that first before getting inside your carb. If it has a stainless low speed screw 2 to 2 1/2 turns out is not uncommon.