getting incredibly hot

[the ultimate warrior]

got an 02 warrior believe its a stock bore has a pro circuit t4 pipe running the air box lid main jet is a 150 42.5 pilot i can start it up and idle it for a minute or so and the header starts smoking and my infrared thermometer reads around 650 degrees timing is spot on ive made sure i have no air leaks cleaned the carb i dunno how many times the motor does not seem to cut out at all either im at my wits end with this thing hoping i can get some advice any help would be awesome

 

[Gen1Pat]

You need to plug chop it. Sounds like your pilot jet is too small, and it is running lean. If I remember correctly, 42.5 is the stock pilot jet. With a pipe, you'll have to re-jet it richer to compensate. Let it run at idle until it is at operating temp. Then, shut it down and pull out the spark plug. WEAR gloves, plug is HOT!! Look at the center and ground electrodes. They, and the tip of the porcelain, should be the color of a brown paper bag, or "golden brown". If it's lighter then that, it's lean. Only use genuine Mikuni jets. DO NOT USE DYNA-JET.

 

[jimmyde78]

^^^^^ yup.... try a 45 pilot jet in there

 

[the ultimate warrior]

Thanks guys plug is perfect cardboard brown.....I've heard I could be 180 degrees out so that's my next thing to check.....as of now the longest I can run it is about 20 seconds

 

[Gen1Pat]

No such thing as being 180* out on a single cylinder four stroke. Soon as you turn the crank 360*, it is on the exhaust stroke, and the cam will be 180* away from it's timing mark. Move the cam sprocket 180* back to it's timing mark, without moving the crank, and you go from the exhaust stroke to the compression stroke. So, mechanically, there is no 180* out. If the woodruff key is sheered off for the flywheel, then yes the ignition timing COULD be out 180*. BUT, if the ignition timing was 180* out, then it would be firing on the exhaust stroke and not run at all.