400 ex axles & lectron carbs

Hey guys as a first time poster I hope someone can help.My first question is will the 250r axles fit the 400ex and what needs to be modified if it will.2nd has anyone used the lectron carb on their 400.Ibought one on e-bay and when i installed it was to short to reach the airbox boot and it also hit the bottom of fuel tank.Also what has been the best mods to bring some life to the somewhat sluggish ex.Thanks Xracer

i'll answer your axle question.Yes, the 250r axle fits. you need the wheel hubs. the 400ex brake hub works on the R axle. there's really no difference. if you go to a +4 250r axle it's like +6 on the 400ex cause the 250r axle is longer than the +4 400ex axle.

[400exJOE]

although I have not installed my 440 or lectron yet (hopefully this w/e) I can help you out some. 3 things that will turn your horse power up are (in no perticular order) #1: aftermarket exhaust. Stay away from dg or cobra. And, only a slip-on is needed. Forget the header. #2: a high compression stock bore piston or bigger bore if you want. Don't go over 11-1 compression though unless you don't mine making a 50/50 mix or running straight race gas ($4 a gallon!) J.E. Pistons make a 10.8-1 compression piston in all sizes-400, 406, 416, 425, 440...etc. #3: an xr400 dirtbike cam. This cam is more aggressive than the stocker and does not require hardening of the rockers to be used. That is whats next on my list. As for the Lectron questions, get a small plate of metal and drill two holes in it. Place the holes about 1" apart. Remove the one bolt at the back of the air box and screw one bolt into the frame hole and one hole of the plate and another one throught the other hole of the plate into the air box. This will move your air box foward 1" to meet the carb. Also, the carb has to be mounted at a 1 o'clock position to clear the gas tank. As for jetting the carb, remove the top cover and there is a needle which you turn in or out to make it richer or leaner. Not sure which is which though. Hope this helps, JOE

[chris29]

Yes they both will work You have to have the 250r hubs, carrier, and It would be good to put the brake on because 250r brake has 2 pistons in it insted of 1 like the 400 and the brake roator is shorter and that makes for better ground clearance. Your lectron carb is fine you just have to move the airbox up like 400ex joe said. And oh yeah better get used to taking it apart and cleaning it all the time. I have one on mine and the littlest piece of dirt will get in it and make the slide stick. So I clean mine after every 2 races.

you don't need the carrier for the axle. the 400's works. their actually the same i belive. but if your looking for aftermarkt parts might as well throw in a tappered or double bearing design. the 250r axle also dosen't taper down as much as the 250r axle which makes the 250r axle stronger than the 400 and the 250 hubs are stronger