I have a 2003 Honda 400ex that will not start. It has compression, changed the stator, spark, and the timing is on. Dont know what it could be. Please help. ???

 

The three things you have to have in order for motor to fire over.
-Compression
-Spark
-Fuel

Looks like you have fuel to check. make sure its flowing good and your carb is clean.
Did it just al of a sudden stop turning over.....? what the background on the bike....

 

Bought this way. It has a slip on yosh pipe so i jetted it different as it was recommended. It has a 155 main and a 42 pilot. Cleaned the carb. Removed petcock from tank and looked ok. When we tried to pull start it, it fires for about 2 seconds and dies???

 

does it run with when choked, but die when its not?

 

No Tried choking it but didnt seem to make any difference. It would take off and die then a little later take off again???

 

had a 2000 400ex that wouldn't start,it had compression,spark and fuel,I found that the timing chain had jump time [common on the 400's with some hours on],replaced timing chain,retimed and it took right off

 

Seems like an ignition problem though. When we pulled it , it would take off and almoast ram my other quad then die. It runs for like a couple of seconds then like i turn the switch off it dies. It does this over and over. I had the timing chain off and put a differant one on that came in the spares box with the machine. The original chain was about 1/2 a tooth off when I lined up the marks. The other chain is almoast dead on. Is the chain that critical. I tried a ign. box from a 2005 but it was the same. This thing has a toggle switch instead of the key because he used to race it. It had a 440 kit on it but that engine blew. This engine was bought off of e-bay but he couldn't get it going so he sold it to me. compression ,120psi, timing t in window when cranking, carb apart and cleaned, new plug, differant stator, starting fluid didn't help, drained tank and refilled with new gas. I'm pulling my hair out , it should start.

 

are the valves seating correctly?

 

I do believe so because i had checked them when i had it apart

 

I hope someone can answer this because I'm having the exact same problem with an 03 400EX.

The only thing I haven't checked is the timing, but when I put the engine back together it was TDC. May have slipped a link.