I know it's there, because it's necessary to adjust it when jetting for a pipe. But where?! Can someone at least tell me what side to look on? Did I just not look hard enough? I'm used to Harleys where you have to drill out a little cap that the factory installs over the screw so people don't mess with it, and those are kehin carbed as well. Do I have to do the same type of thing to get to the screw on the 400ex?

 

none

 

This has pictures... Also, on 2005 and up, it take a special tool to adjust the screw. No more flat blade screwdriver slot.

http://www.dynojet.com/pdf/Q107.pdf

 

Thanks for the help. Now that I know where the screw is, what condition does it create by turning it in vs. out? If it's an air screw then turning it out (counterclockwise) should make it leaner, right?
Mine is a 2004 so I won't need anything special to adjust it.

 

Somebody correct me if I'm wrong, because I'm not 100% sure of myself here... If the screw is on air filter side of the fuel bowl, you are metering air (turning in richens, out leans). If the screw is on the engine side of the fuel bowl, you are metering fuel (turning in leans, out richens).

From the picture, it looks like it's on the engine side so you are metering fuel. Turning in leans, out richens.

I hope I'm right... HondaMechanic would know for sure [img]i/expressions/face-icon-small-happy.gif[/img]

 

On all 4 strokes the screw adjusts fuel so turning in (clockwise) is less fuel and turning out (counter clockwise) is more fuel. I recently bought a very handy motion pro 12 inch flexible screw driver that most mechanics use to fine tune this enrichment screw when motor is hot. Cost is about $30. and is worth the money. I also have motion pro stubby screw driver made for this. The stubby works OK with cold motor but is hard to fine tune for max idle with hot motor.

 

Do yourself a big favor and replace the stock screw with an adjustable one. MSR makes a great one. It then becomes a breeze to just reach down and make fine adjustment. Do a search on google and you get tons of hit's about fuels screws, also try exriders.com for more detaied infomation.

 

I think now I've got it straightened out. Rich=out, Lean=in, screw is mounted vertically in front of the bowl. Thanks for all the help everyone

 

MSRs website said there screw fits a keihin FCR carb......is this the carb thats on the 400EX?

 

remember that the fuel screw is a fine tune adjustment for the jetting at idle and low throttle positions. it will not change the jetting, or not much at all, at higher throttle positions.