I have a 04 AC 400 auto and until this year have not had any problems. Now when it gets hot, it starts missing and eventually quits all of a sudden. It will turn over but it won't start. When it cools, it starts and runs like nothing ever happened. Has anyone had this problem?

 

i had a problem like that once with a brand new one where it would die after i went about a half a mile then i would crank and crank and crank on it finally it would start and sometimes i could go a ways and sometimes i wouldn't go anywhere and it would die. turned out i had a piece of plastic in my carb so i guess try cleaning the carb and also change the plug.

 

Sounds like the ignition CDI box is going bad. Gets hot and it quits producing spark. You can check it, the next time it quits, have a spare spark plug, pull the wire off the plug in the engine and crank the engine with the plug on the wire and ground the base of the plug. Spark, it's not ignition, no spark it's ignition. Has to be either the CDI box, the sensor (trigger) in the flywheel or a bad wire. Normally carb problems don't just shut off the motor like the key is switched off, the motor sputters as it leans out and then dies.

 

Sounds like the exact problem Ihad on an old Suzuki. And BEar is right onthe money, it was the CDI box. Very expensive fix.

Of course, I discoverd a place in Canada that rebuilds the CDI boxes, after I purchased a new one for $450!

The fix I used for a short time was to pack snow around it and ride. Then summer rolled around and it would not work.

There is a test procedure in the service manual I believe.

SJ

 

Not so fast on the CDI box - I have had a similar problem and fixed it absolutely - for a whopping 8-bucks. I have, (had really I just traded it today for an 06 trv), a 2003 400 Auto. When the quad got hot, (especially at higher speeds), it would just plain quit. I tried Bear's tried and true spark plug test and found I was getting very litte spark. A wise old owl who I ride with told me to go get a new spark plug cap. I did. Problem solved!

The spark plug caps have insulation in them that can break down and wear out, (even tiny cracks). Go get yourself a new spark plug cap before you start spending money you don't need to necessarily spend. This was happening to me at 850-miles and never happened again and I just traded it today with 1,559 miles.

 

You are right, but at this point we don't know what is happening and until he tests we won't really know. I can't really include the cap or wire in the equation until we know if there is any spark at all. Your problem is an exception BTW, not the norm. Even though I have seen it before.

 

You are a wise old bear... [img]i/expressions/face-icon-small-smile.gif[/img] I think he's getting spark, (but you're right - it would help to know for sure), as his quad runs until hot and shuts down, (same thing mine did). It also starts and runs after it cools down, (same thing my did). It seems all too similar and I figured a 8-buck cap may be worth a purchase...

PS: I read your post in another thread about the tire size-to-gear ratio...Absolutely brilliant. Where do you learn this stuff?? It's proof that one really does learn something new every single day. I never would have though about larger tires actually reducung gear ratio...I just oversimplified it by terms of weight. You my friend, should write a column or a book....