'77 Cyclone carb problems

[JDChad1]

Okay, awhile back I picked up this sled off ebay for $50 and am in process of trying my hand at getting it running.

First a little background on where I am at:

I replaced the original 340/22 with a rebuilt 440/21 from a '73 jdx8. The old engine stator was toast and the mice had built a pretty substantial nest under the cowling, so went with the 440/21 and points. The engine drops right in easy. I switched the walbro intake on the 440 to the mikuni intake from the 340. I bought a new V34mm Mikuni from Dennis Kirk and installed it. The choke and throttle cable are installed. I have the JD Service manual for this sled. I rebuilt the fuel pump, replaced the fuel lines, and am running 50:1 from a jug. The engine has about 115-120 psi compression on both sides. My clutch engages at about 3800/400 rpm. The air box is installed.

The carb is set up as follows:

Main Jet: 400
Jet Needle: 6FL14 on third ring
Needle Jet: Q-0
Throttle Valve: 2.0
Pilot Jet: 30
Air Screw: approx 2 turns

This as close as I could come at the time as far as jets, etc. The throttle valve is bottomed out when the throttle is released. I'm not totally sure of the choke set, but it seems alright. It does change the way the motor runs.

Anyway, today I got it all put together and assembled and ready to go. I put on the choke gave it a few pulls and it came to life. Now my problem: I can't get it to run without the choke on all the way. With the choke on, I can set the idle down to 2400 or so and it will run fine. It smokes alot so I believe it is way rich this way. If I flip off the choke, it runs fine for a couple seconds. The engine sounds betterand smokes less, but it starts to get doggy. The idle falls off. It bogs and dies. If I flip the choke back on during this, it will recover and keep running. It will run if the choke is on a fraction, but takes alot of feathering. When it did die, I could flip on the choke and it would always fire up again on the first pull.

It was about 10 degrees F today. After playing with this for awhile, I pulled the plugs and they were a very dark brown which to me says too rich as does the excessive smoke with the choke on.

So, any ideas in where to go with this? It is one of those last minute projects I'm scrambling to get going to take to Waconia to test out on the lake. I'd really appreciate any insight you could give me. I have read the manual but have no previous experience with mikuni carbs. I realize this isn't the normal application for engine/carb setup, but this is what I had to work with. Please help if you can.

Thanks,
Chad

[Danzig]

Get some extra pilots and try a 25 or a 35. See if this will help. If it were mine I would go with the larger pilot. This is your idle circuit and sounds as if this is your problem right now.

[JDT]

The carb slide is NOT suppose to bottom out. Has to be slightly open to maintain idle speed. Crank up the cable adjuster a couple of turns, flip choke on and start. Flip choke off and see what happens. Adjust as needed.

Todd