I had 20 city miles on a new 351. After about 4 miles on the highway at 65 the bike just quit. Came to a stop and was able to restart. Same thing 2 miles later. 3rd time wouldn't. After overnight on my trailer started right up on choke. Idled for one minute, quit, and wont restart. Any clues?

 

You need to find out what is missing. Spark or gas.

Fire it up, run it till it quits and give it a squirt of gasoline directly in the carb See if it will start on that.

Next (or first) Pull the spark plug, inspect it, hook it up to the wire, make sure the spark plug is grounded and crank the engine. See if you have spark.

Motor oil full? Full gas tank? All lines and hoses hooked up? Radiator full?

Good luck.

Its 9*f here with lots of snow. I aint going no where on the bike.

 

Well if you were doin 65 when it stalled, at least that rules out your idle circuit in the carb.

As David said, check your spark. Sounds like you may have a loose connection issue. IIRC you just had your motor apart for the 351 kit, that could bring on other issues related to timing if the teeth weren't set properly.

 

Either loose electrical connection, or, my first guess would be something as simple as a crimped/occluded carb vent line or a gas tank vent line not on correct. If it were timing-related, it would show up immediately, not run for a while then quit, then run, then quit.

 

You have the timing right.

Spark? Gas?

David

 

I'm guessing a clogged fuel filter. Been here before in several machines.

 

Oh, yeah! Does your bike still have that little screen filter that goes in the fitting on the petcock where the fuel line enters?

 

Checking all the above suggestions. The fuel filter should go after the petcockj and before the carb. Right?

 

did you have the carb apart when you did the big bore kit to rejet?
FLoat stuck?
did you take the fuel line off the catb and open the petcock to see if fuel is flowing to the carb? Pinched vent line. If no fuel flows or trickles out, open the gas tank cap and see if there is better flow.

 

Fuel filter was my first guess, but only if you have put an aftermarket fuel filter on your bike. The klx's don't come stock with a fuel filter. I think they have screen material on the pickups of the petcock in the tank, but not a actual fuel filter. It's a good idea to add one, and yes it should be at some point after the petcock and before the carb. The fact that you ask where it is makes me believe that you haven't put one on, so your problem may be something else. Spark and gas, as everyone has said, see which one is missing. Check the ground for the coil. The coil had to be removed for the 351 swap, maybe it didn't get good contact when it was re installed. ????????
Dan