I just bought a used 400EX with WB E-Series Exhaust, K&N Filter, WB Rev Kit and everything else is stock. It seems to be running o.k., but I have nothing to compare it with. Everyone tells me to put a bigger main jet. Anyone else running same setup. I am at sea level. I want my quad to RIP!

 

WHat size is in it now? Check your plug.

 

Another thing to do is to take off the airbox lid however i would reccomend you not do it. You squeeze some more power out of the machine when you take of the lid. However, I was riding it one day with the airbox off and i found myself about 2 feet under water and stuck, I was lucky it didn't suck and water into the engion, cause my airbox was full. So if you are just riding around the yard or something, you might try it.

 

stock 148 main jet. It didn't come with a manual, so how hard is it to check plug?

 

it should rip... if you're not comparing it to a 416,425,440, etc. ?

 

Rest In Peace? you could burn it.

 

To check your plug, Put a new one in, Run it in a straight line through all the gears, pinned in each gear, when you hit the top of 5th, hit the kill switch to off and hold the throttle wide open until you come to a stop. Dont use the brakes to stop, let it stop itself. Then take the plug out and look at it. If its a tan color, it perfect. If its black your too rich. If its white, your running lean. I think thats how it's done.

 

Run a 170 with no air box lid and a 14 tooth front sprocket, it will amaze you when the front end comes up in 5th, it's awsome. If you leave the lid on I think a 165 is about right. You'll have to play with the air screw, I run 3 turns out.

 

Fast453ex. Do you think if i just have a slip on and a K&N that a 165 or 170 would be too rich if i am riding at sea level. The dealer had a 155 which I'll try but if you think i would be better off with maybe a 160 or higher then I'll try it!

 

Thats what I thought that he meant. hehe