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johnnydufus
05-09-2005, 04:46 PM
well i was fiddling with my 400ex trying to find my problem and i came across my revbox, i took it off and i noticed a W and a B engraved on the side. i've heard things about these revboxes that arent good. like how they are a xr50 box with a modification. and how that they wont work unless the battery is fully charged.

we checked my spark and i have none whatsoever, could this be from the revbox not working properaly or something else?

i'm charging my battery at the moment and i hope it will work again..

any ideas?

thanks,
johnny
F-16Guy
05-10-2005, 10:17 AM
It's an XR250R box. The reason people have problems is that there's an anti-kickback circuit that prevents spark below a certain rpm. This circuit prevents the kick starter from whapping you in the leg if you are kicking the XR over slowly (getting on the compression stroke). The problem people have on the 400ex is that when they put a high compression, over-sized piston in it, the electric starter won't turn the engine over fast enough to overcome the anti-kickback circuit unless the battery is FULLY charged.
johnnydufus
05-10-2005, 08:20 PM
my bike wont even try to turn over.... i dont know what to do besides check all the connections
cals400ex
05-10-2005, 11:10 PM
get a stock rev box and change the plug. you should be able to find a stock one pretty cheap in the for sale section here.
F-16Guy
05-11-2005, 11:59 AM
Originally posted by johnnydufus
my bike wont even try to turn over.... i dont know what to do besides check all the connections
You may have a number of problems. You may have a bad run/stop switch, a bad coil, a problem in the harness somewhere, or there could be a couple of wires swapped. Did it run good and then just die one day, or did you buy it not running?
johnnydufus
05-11-2005, 03:36 PM
it died in the middle of my race
cals400ex
05-11-2005, 04:56 PM
ignore my first post. i read your problem incorrectly. :D
johnnydufus
05-11-2005, 06:54 PM
ok i ran a few tests on it. when i hit the start button absolutely nothing at all happens. all connections around the battery are still good and all the connections around the front revbox are still good. i did get it to try to start by jamming a screwdriver into the silenoid (sp?) and it tried to turn over but it didnt sound like any compression is coming out. any ideas?

i'm sorry guys for not having a clue on this. when it comes to electrical i am brain dead
05-12-2005, 05:50 AM
may sound dumb but I have done this my self about 30 times, did you make shure your kill switch is on?
cals400ex
05-12-2005, 11:02 AM
Originally posted by mittimj
may sound dumb but I have done this my self about 30 times, did you make shure your kill switch is on?


he said it wasn't even turning over though.
journeyman
05-12-2005, 02:48 PM
my 05 does this all the time..maybe its the same problem...check the fuse block under the left rear fender above the battery...wiggle it back and forth and then try to start
johnnydufus
05-12-2005, 02:54 PM
Originally posted by mittimj
may sound dumb but I have done this my self about 30 times, did you make shure your kill switch is on?

i've done this to myself plenty of times aswell but this isnt the problem

when i turn on my key and the bike is in nuetral the light doenst even come on. i'll try the fuse thing in a minute