Hey fellas, I have had my 05 AC300 4x4 since 500 miles, now has 2500ish

Started running rough and over a few weeks went to sputtering at high rpm's. cranks up purrrfectly and does just that purrs...when i go to ride it it spitts/sputters dies. but will idle for ever.

What i have done....
plug gapped to specs
new airfilter (not that it would help but what the hey)
cleaned carb x3,
bought all new factory jets and air needle spring thing finally
turned the spring snug then back 2 1/2times to set it (was told to do that)
Attempted compression test, wrong size fitting and not paying 75 for a whole set, auto parts stores here do not have the right fitting to rent or borrow

found frayed wire coming off the ignition coil ( so i assume,)its the wire from the plug to a black thing bolted to frame and goes back from there to harness then batt. I cut the wire back a few inches, new wire and ring terminal. was very hopeful it was the prob, NOPE

How can i troubleshoot this it cant be a carb issue.

Thanks for any help, i really cant afford the 90/hr for cycle places to tell me its a wire.

 

Check valve adjustment, 250/300's will eat the intake valve over time and check battery voltage while running, shouldn't be over 15.5volts while doing a brief wot.

 

OK thanks, Intake valve huh? yikes

 

First thing is to get you a service manual. I think you can find one for your model here: "K&T Parts House Lawn Mower Parts and Chain Saw & Trimmer Parts"
Next, get you a multimeter and get to work. I would start with voltages around the coil and stator. Several people started to tell me the stator was bad on mine because AC had some issues and my model year was one of the suspect years. To make a long story short, my stator is okay but I have issues elsewhere in the electrical system. My 400 was doing the same as yours but mine would start running bad after about 1/2 hour or so. I am suspecting the coil and replaced that last night but have not had a chance to ride it and figure out if it is fixed....hoping to tonight.

One other thing to check first is to make sure that you vacuum lines from your carb. and fuel tank are clear and not kinked. Several folks have run into that issue and that is an easy fix (blow out the vacuum line).

Keep us up to date. There is a lot of knowledge on this forum.

 

May try unplugging voltage regulater first this could be an easy fix, is common to have voltage regulater failures....Just an ideal..

 

also ckeck gas in the gas tank make sure no water or dirt in tank. if you need to clean carb you should always check gas tank gas. most of the time ther is water in the gas because the gas cap plastic piece for gauge is missing or cracked. you can put an omc 6gal gas cap on the arctic cat 4 wheeler and you do not have this problem any more.