My 87 trx250x stalls when it get warm. Sometimes when it stalls it starts right back up and other times it does not. I was not getting a sparks at the end of the coil wire. This was checked with out the cap on and touching bare wire to the engine block. I tried installing a new ignition coil but it did not help. Does anyone have any suggestions?

 

Thats not the recommended way to check for spark. put the cap back on, the wire, then put in a spark plug, and hold the metal body of the spark plug, on the cylinder or head, and spin the motor. Look at the spark plug gap, for the spark.
Your way could hurt the cdi...there needs to be an electrical load on that circuit, and you effecivly make it a short, by going directly to ground like that. The spark plug is the proper load in the circuit.
When it stalls, was it at idle? How does it idle cold? is there any exhaust smoke?

 

When you first start it it wont idle on its own for the first 10-15mins. When Im riding it just turns off and sometimes it will refire and sometimes it wont.

 

Mine did the same thing, and I spent all sorts of money having people try to fix it. but it was an easy fix. its your wiring harness. you may have a loose conection somewhere. mine was loose in the white plastic plug that connected to the CDI box. you cant just fix the connection into the plug, these things are very picky and you need the original parts. I bought a new used wiring harness off ebay and it fixed the problem. all the connections on your wiring harness must be snug in order for them to work propperly.
believe me I spent over $600 trying to fix this problem befor I found out it was only my wiring harness.

 

I checked all of my connections and they are all snug.

 

Ok, you know the plug that connects to the cdi box? check the four wires that go into the back of the white plug if they are even a little loose in that white plug it will cause problems.

 

OK I will check that. Thanks

 

I think I need a cdi box. Could I use one off a trx300ex or trx400ex ? They look the same.

 

I think you could use the one off a 300ex, but Im not for sure. you should ask your local honda dealer. but dont buy one from tham. you can get cdi boxes off ebay usually brand new ones for alot less than the dealer will sell you one for.

 

The Honda dealer wanted $120 for a stock one. I bought a new performance one for $76.