2010 John Deere Gator HPX v-twin gas mis fire under load (2 Viewers)

Jan 7, 2016
I have a 2010 HPX with a Kawasaki vtwin engine. The machine starts fine and runs great until gas is applied then it spits and sputters and sometimes it will take off. Other times it seems to be running on only 1 cylinder. Here is a list of items I have done. Gator has 1743 hrs

Fuel pump flow test
Changed fuel filter
Changed oil made sure it was not overfull
Drained gas tank then added 93 octane
Checked valve clearance. In spec
Cleaned carb. Carb looked very good for most part but did have a lot of carbon. Main jets were 57 air adjustment screws set at 2 1/2 turns each I do not know the factory settings. this is what it was at. IN and it leans it out. out and it richens. I am slightly above sea level.
Removed plugs. A lot of carbon put new plugs in BPR2ES
Spark arrestor removed.
Ran engine with out air intake -no change
Replaced one coil - my thought was it was loosing a cylinder. I could not find a test for this in the service manual. -no changed swapped the other two coils no change
compression checked both cyl about the same 95psi

A slow acceleration and the engine runs fine, but a quick stop on the throttle and it spits and sputters until it gets up to speed. Starts up and idles perfect every time.
I posted on john deere gator forum web site but have had no luck

Here are my questions
1. Has anyone had a igniter moduale failure on these? This is the first item before the coils on the wire diagram
2. My carbon problems, has anyone adjusted the carb to lean it out a little with the two adjustment screws on top? How about a hotter spark plug?
3. A thought I had was the exhaust is plugged robbing power but that may not explain the mis fire.
4. On my carb the parts manual shows two pilot jets on outside of either carb. Mine did not have those. Are there different carbs for different gas machines?
5. another guess is an air leak in the intake gasket or carb gasket. I tried spraying penetrating oil around gasket- no change- Is there a "smoke test" to determine a leaking gasket?
6. with the amount of carbon mabie it has buildup around the valves? Anyone used sea foam with good luck on these?

Thanks for any help
Jan 7, 2016
Sorry it took me so long to update this thread. I ordered new carb gasket kit which included intake gaskets and carb gaskets and the plastic spacer plate. I also replaced all gaskets in the carb and the jets in carb but saved the old ones as they looked fine (37.5 pilot and 75 main). I set the idle mixture screws at 2 turns out at first then checked the plugs after few hours then turned the rear out another 1/2 turn and the front out 1/4 turn. Then I adjusted the idle again.

The gasket material was very dried and I am assuming it was sucking air in at some point making the engine stumble. It has been running great now for about 70hrs. Still is cold blooded upon startup however, the choke helps this but nobody uses it for some reason.

One thing that I have learned are that Kawasaki engines will not run well if there is the slightest air intake leak around an intake gasket. I have had a similar problem on a Kawasaki FE 400D in a club car gold cart that had a hesitation on startup as well.


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