2003 Conquest Rough Engine

[deermedo]

Bought a 03 Conquest that has 120 hours on it and has been sitting for a while.
It is difficult to start and must warm up with the choke partially on to run.
After it is well warmed up it will run without the choke but backfires a bit and then picks up the governor making for rough low speed operation.
Any ideas??
Thanks John

[dromas]

did it sit with old gas in the carb. if so pull it off and clean it out, old gas turns to a brown varnish and can cause all kinds of problems

[Castro]

Ok, remove old fuel and replace fuel lines and filter. If you really want it to perform throw in a 5-6 psi low pressure fuel pump in line with your Briggs diaphragm pump ( mount it behind seat on rear rail). Also good idea to clean the carb. At this point if you have a 2004 or older Argo that hasn't had this done then its time. The lines weaken and collapse and the pump is garbage. Do this and your machine will really perform, be sure to use a toggle switch for the fuel pump, I tied in some LEDs from auto zone so I never forget it on. If you don't add the fuel pump you will be disappointed when you need the power and your going up a steep incline

[Slimpickin]

I'm thinking it's a kawasaki engine. Take the valve covers off and see if the pushrods are in place. I had one that sounded the same. It seemed to run fine once it was warmed up, but was not powering up.

Slim

[Rock Doctor]

That's not uncommon with the 20hp Kawi. Your problem is with the Idle jet/Siphon tube in the carb. They are plugged or are plugging up. Pull the top off your carb, clean out the float bowl, and clean the tiny little holes in the siphon tube and the pilot jet (Torch Tip Cleaner works great). The reason you are running rough is becouse you are not getting enough fuel to idle, so the governor is cycling just a bit an dumping fuel into the carb, in an attemt to keep the engine running.
As mentioned, the Kawi engines really don't like old fuel. Old fuel can and will cause your Pushrods to stick or sieze up. If this happens, you migh be running with a valve open, or with a bent pushrod. If you suspect that the fuel is old in your machine, you can add a cup or 2 of ATF to the fuel to help lube things up. It will smoke a bit, but that's better than tearing your tappet covers off and straightening pushrods with hammerstones.


RD

[rotaxmax]

The problem is usually clogged passages in the carb. I have a lot of snowmobile experience, and the described symptoms are almost always clogged pilot jets from oxygenated fuel sitting in the carb too long,reacting to the aluminum carburetor. Clean all small passages in the carb with a small diameter wire and compressed air, and reassemble. If it runs good for awhile then relapses, you may have more debris coming from the rest if the fuel system, such as a fuel pump. The ethanol in oxy fuel is corrosive to aluminum. You will have fewer problems if you use non-oxy fuel. Especially if your machine sits idle for long periods. I learned this the hard way on snowmobiles that sat all summer, and outboard motors that sat all winter. We used to race go karts that ran on pure methanol (modified Briggs four strokes) and the carb passages would clog in just two weeks if we didn't flush them with pure gasoline between races. good luck, and don't get discouraged if you have to take the carb apart a few times before you get it clear.