Super Jet Tuning question...

[MADMAT]

I was trying to figure out what was wrong with a friends dual 38 701 today......to me it felt like a bad plug or plug wire. Cut the wires back with new terminals....no change....new plugs no change....swapped out stock CDI for a known good MSD.....woke up the ski! But no change in the bad running. Plugs looked dry and didn't match colors after all of this. Richened it up a little...rode it....plugs look same.....richened up a lot! Just to see if it made the plugs change. They didn't....they still look dry and the back cylinder is way to dry and white. It runs on either front or back or both so it is getting at least some fuel and they both have a great spark. Compression is a even 185 in both and no sputtering at all. (as if it had a bad Oring). Internal carb filters????

 

[BruceSki]

Have you opened them up yet?

Pull the return line off the tank and see if fuel comes out of it while ski is running.

We have been issues with skis clogging up the restrictor in the slave carb on dual 38's recently.

Acts really funny and you scratch your head swapping electrics and stuff chasing it.

 

[MADMAT]

Good idea! I should have pulled that return line to see if it was really flowing well!

 

[BruceSki]

Should just dribble out at idle.

Mine was so bad it did nothing. Clogged up solid. That restrictor is so small a grain of sand could do it.

 

[blaster800]

Matt thats the exact symptoms my dual 44 showed and acted like at the Erie freeride even the white rear plug , I got home , pulled the carbs and found rusty water in the rear carb , I cleaned them out and its good as new FWIW

 

[motozachl]

Pulled the carbs apart, nothing looking obvious yet. Needle isn't stuck, no rusty water frank, internal filters good, reeds in minty shape. Where is that tiny restrictor so that I can inspect that?

 

[BruceSki]

It's the blank dummy plate on the carb without a fuel pump.

Blow air through the return where it comes in from the other carb and see if its coming out the return line.

Remove this plate to do this.

 

[motozachl]

It's the blank dummy plate on the carb without a fuel pump.
Blow air through the return where it comes in from the other carb and see if its coming out the return line.
Remove this plate to do this.

Did that last night, nothing blocked. Also pulled the head, o-rings are great also compression was 185 and the cross hatching of the honing is intact. What's next?

 

[blaster800]

Coil ??? IDK But I would try one !

 

[motozachl]

I will changed it out once its back together. Performed a leakdown test and dropped 1psi for ten minutes, sprayed the entire engine with soapy water. The only minor leak was the rear main seal, would this cause the rear cylinder to run lean?

 

[Jp79]

I've had a main seal ruin the party, no matter what you do you can't get it to run just right. It was letting air in (wouldn't pass the leak down test) there for leaning the cylinder.

 

[550headache]

isn't 1 psi in ten minutes acceptable?

 

[mybad]

If the cdi checked out good.......I would swap the coils with known working ones. The carbs looked good when we had them apart. I had this same problem......it was a bad coil. Mine would spark on a ground check but not under a load.

 

[mybad]

And if your previous motor had the same problem......it must be electrical.

 

[motozachl]

All back together with new seals and it runs like a champ!!!

 

[MADMAT]

I just hope we put them in right! I just read a thread that said use 1211 around edges of the seals or grease between the 2 back seals at least. I never have...but I use OEM.....and yours looked like aftermarket seals...