Ok so I had my 400ex taken to a mechanic and he cleaned and supposedly tuned the carb. The bike is stock except for the pro circut slip on exhaust. It ran kinda ok before I took it to go get tuned but the bike was a really slow on throttle response. It would bog on first a little and it would go away. Well any ways… So he supposedly tuned it and everything. When I tried out the bike it was running weird it sounded much louder from the engine. It also poped a lot! When I was in first gear it would pop a lot! It wouldn't really respond and sounds like it wants to die. Then once I get to 2 or 3rd gear it stops popping and runs normal. I'm guessing the bike is jetted incorrectly. It only pops when I give it throttle not when I let it go. When I snap the throttle it revs fine but when I hold it pops and it sounds horrible. And it doesn't blow out any smoke at all. When I hold the throttle is pops a lot and wont stop unless I stop reving the engine. And I took my lid of the air box and it was worse. What size jets would you recommend for my bike? I also want to run no air lid. And also what pilot jet size I heard the 42 pilot jet gets rid of bogs. What size main and pilot jets should I use and what position should I put the clip on for the needle and mixture screw setting. And my elevation where I live is about 3,000 to 5,000 feet of elevation. Thanks for any help! :)
Read more: 2002 Honda 400ex Running bad poping and backfiring?
