400ex wont start after rebuild...troubleshooting! HELP!

[LG300ex]

just rebuilt the entire engine because i had to swap the bottom end center cases off of a previous engine, its all back together now and when i turn the key the neutral light comes on, I am getting gas to the bottom of the plug after turning it over (turns over strong) I am getting a good spark to the plug, I have compression, I have air flow, and gas is getting to the carb. Im stumped. My only thoughts are my float in my carb is stuck open or closed? or my timing is off? can any help me with ideas??? thanks guys

[CJM]

so its cranking right? It doesnt sputter or anything just cranks over and over and over?

Try push starting it, if it fires up you know its possibly a timing issue (most likely valves.

Id start by checking the timing, anytime you have the topend apart the valves go out of adjustment. I would also check the cam sprocket to make sure its in time as well.

Also when you put it back together (assuming you have a stock cam) you made sure your decompression mechanism was on there right?

[AtvKid4Eva]

sounds like your timing is off. thats usually the culprit after a rebuilt involving the top end. Re check it.

[rocky_mtn_honda]

Mine wouldn't start after building mine, but it wasn't the decompressor mechanism itself, it was the little dowel pin and spring that I neglected to put back into the head.