340 Cyclone Flooding

[cycloneeh]

Good evening,

I am having an issue with my 78 340 Cyclone flooding to the point where it still runs, barely, but there is fuel coming out of the exhaust. Turning the choke on or off makes no difference. Proper adjustment of the choke is confirmed as evidenced by the imprint in the rubber on the bottom of the new plunger and play in the cable. When I shut off the gas and the engine leans out, it runs perfect - confirming good spark. The sled has been completely rebuilt top to bottom, including the fuel pump, carbs, ignition, coils, etc.

The carbs have been completely rebuilt and are set to factory jetting. The needle and seat work fine and were confirmed by blowing in the fuel line while the carb was upside down - no air could be blown through. Floats float as I placed them in a glass of water to confirm. When upside down the float arm is parallel. I have played with the pilot jets (smaller) to reduce fuel at low speed yet this has not made a difference.

The fuel pump has been pressure tested and is good.

Do I continue playing with jetting?

Any ideas are welcomed.

Allan

[SS440-80]

I don't know how the airbox looks like on Cyclones (was never sold in Sweden) but could you have a stop in the airbox? That would work just like having full choke.

[cycloneeh]

Currently I have been trouble shooting without the air box installed.

[SS440-80]

OK! So not choked by airbox.
Could it be that the carb is vibrating so much that it makes the carb flood? I remember reading about something like that happening on some other Deere sled, think it was Liquifire?

[cycloneeh]

Thanks for the suggestion.
The sled starts fine but will not idle. It almost seems like it drops a cylinder as it bogs badly when any throttle is applied and eventually gas will start spraying out of the exhaust. Once I turn off the fuel valve and it starts to starve for gas, the machine runs and sounds great for 5 seconds before I have to turn the gas back on to keep it running. I have tried reducing the pilot jet but so far it doesn't seem to have any affect. Thinking I might drop the needle jet one notch and try a smaller main jet to see what might happen.

Any other ideas?

[cycloneeh]

Does anyone have any other suggestions, why this sled is running so rich?

[jdjock]

Did it run ok before you rebuilt the carburetor. What type of cd box did you use. Could be losing one cylinder at speed. Should at least idle though. I think it has to be the choke system. With the airbox off, take a small mirror and look at the valve itself as you move the choke lever. Should be 3 positions. All the way open, half way open and all the way closed with no gap.

[Vader440]

Did you ever figure this out? Is it a Mikuni Carb with the plunger type choke?

[400brian]

Very possible that the enrichener plunger was not adjusted correctly, was worn out, or the enrichener orifice was bad.

I had a 76 340 Cyclone that was running way too rich last winter. Looking down the bore, the orifice was really rough looking, I swapped in a carb with a new looking orifice and it was a totally different sled.