Hi everyone,
New to the forum here. I recently have recieved a 2006 trx400ex. It was sitting for a year and a half. Wouldn't start or crank when I recieved it. I installed new battery. New namura 11:1 piston. New rocker arms. The works. Cleaned carb. Fuel lines. Cleaned Vacuum line. No air filter. Replaced sheared woodruff key. (That was a piece of work! 5 minutes max)

I have been working non stop on this machine and couldn't figure out what was wrong. I finally found the fuse was my problem. I replaced with 30amp fuse. Now it will turn over but won't start. I adjusted valves. .12 exhaust and .10 intake. Cleaned carb again to make sure. I finally had it turning over and firing. Now when I try to give it gas and start it, it pops and backfires through carb and exhaust. I have about 110 hours of work on this machine. Has HMF pipe. Only aftermarket on it. I need help. My family wants to go to LBL when it starts getting warm! Any help is appreciated. Thanks

 

The exhaust valves should be .005 and intake valves .004
Have you re jetted?
No air filter?

 

Could that cause it to pop while giving it throttle and hitting the start button

 

Not jetted. An no air filter cuz I'm in the process of just gettin to run. When that happens I have a k&n pro flow. And air box has holes drilled in it

 

Removing the air filter, 11:1 piston and aftermarket exhaust requires you to re jet. Even one of those mods requires you to re jet.
When your valves are out of adjustment it makes the motor not want to start easy.

 

Air filter is off. And it wants to start so bad but will fire and keep turnin over. An when I touch the throttle it pops and spits white smoke out of carb and exhaust. An what jet size?

 

When you start adjusting the carb do it with the filter on. Otherwise your findings or tuning wont be accurate.

 

What is the bore size 416, 440, etc and what is your elevation?

 

Elevation.? I'm in west Tennessee. And standard. 399cc

 

Ok, I just found Jackson as a elevation of 410'.
Keep in mind when it comes to jetting no 2 machines are the same. I would start with a 165 main. May have to adjust up or down . But I think its a good place to start.
Also properly adjust those valves before you go any further.