Damn! Where are you located at?

 

I am in NC. But I ordered the cheapest set from china. Anyway, can you answer this question? Is the decompression for hot starts or cold starts? it is extremely hard to start when it is cold, and it will not idol either while cold. But once it warms up and runs for about 5-10 mins, It will idol just fine and start right back up, If you cut it off.

 

All of the 400ex are a pia to cold start, that is a jetting issue than can be easily fixed. The 400ex has a decompression pin in the head.
When adjusting the valves, you want to be on the compression stroke. There is a T mark on the flywheel that should be aligned with the notch in the port of the side case.

 

So when I adjust the valves, It will also adjust the decompression pin too?

 

Hey bud, make sure thats not an exhaust leak at the head. There is a copper ring gasket on each side that people dont usually change after removing exhaust. If the bike pops slightly on decel its an exhaust leak. As far as decompression pin and spring. Discard. None of the aftermarket cams have the ecentric to operate it. Hope you ordered the bent style feeler gauges, if not bend yours at about a half inch from the end on about a thirty five degree angle. Makes it easier to get them in under the rocker. Hope this helps.

 

I can honestly say not all of them start hard. Most folks dont jet properly and that is what makes a bike hard to start.

 

Your not gonna believe this, but I pulled the headers off and they were they, but in pieces. one was split in half, other was fine. Just ordered 2 new ones. Thanks for the help. Will let you know if it still ticks after install. And yes my bike did pop on deceleration.

 

And my bike is also jetted properly. I have the jets that my exhaust manufacture recommends, Sparks racing. It has a 155 main, 42 pilot and no lid, K&N filter w/ outerwears prefilter.

 

There is no adjusting the decompression pin. The pin helps will all starting, the temp is not a factor.
Before you adjust the valves read this article.

Honda ATV 400EX Valve Adjustment Instructions

 

I understand the manufacturer recommended jets are in. You must take a few factors into account. Elevation, Mods,Air temps/Quality and the most important, every bike is different. It takes a bit to get it right but when you do you will know it. Ive had my carb apart so many times the bowl screws are worn out, and I have an advantage to most. Air temp and quality stays pretty consistent and at sea level. You should try to dial in a big bore, ported head, stage three cam,huge LRD headpipe and 450 carb. Its right now and starts with no choke,one pull on the trigger.