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View Full Version : 400EX dies out when WFO


TRXMaddness
07-07-2005, 05:46 AM
Alright I need a little help. When I hold my 400 wide open it wants to fall flat on it's face, only after I have ridden it to for about 10 minutes though. Last night I noticed it had some black smoke coming out from the exhaust and back firing. I know the thing is jetted right. You can see the mods that I have done to it. I also noticed that it only did this after I changed the rev limiter from stock to a XR250 rev limiter. Can some one give me some advice on this? Tonight I will be checking the valve clearance to ensure it is corret along with a changing the spark plug to a colder plug.
Quadworks
07-07-2005, 05:56 AM
Have you tried changing the rev limiter back to stock??
TRXMaddness
07-07-2005, 06:07 AM
Not yet. I'm doing that tonight too.
YZEATER
07-07-2005, 07:21 AM
clean your carb, sounds like it may have water in it.
07-07-2005, 08:34 AM
I was going to say that there may be some derbis in the carb.

is the choke on? may sound like a dumb question but i have left it on b4.
07-07-2005, 08:35 AM
maybe your too rich
TRXMaddness
07-07-2005, 09:26 AM
choke has been removed.
07-07-2005, 09:40 AM
did you re jet after you removed the choke?
TRXMaddness
07-07-2005, 01:19 PM
Never rejetted after removing the choke. What would I have to rejet it to? It's already sitting at what HMF says to on their website. Main Jet 175 and Needle jet set 2 clicks from the top.
07-07-2005, 01:26 PM
it is possible
muddy400EX
07-07-2005, 01:58 PM
take the outerwears off your k&n, mine did the same thing and it ended up being the outerwears wasnt letting enough air in. doubt its whats wrong with yours but it happened to me:)
rneal
07-08-2005, 10:16 AM
Doesn't HMF recommend 2nd position from the bottom for the needle clip?

I also think their recommended jetting settings are on the rich side. I have an 11:1 416 and run a 160 mj and after a plug test, everything looks perfect.

If your seeing black smoke, either your rings are shot or your running rich.
TRXMaddness
07-08-2005, 11:48 AM
HMF does recommend the needle jet to be on the 2 clip position from the bottom and that is where it is sitting. Must be running rich, because the rings are brand new. I will probably have to change the mj.

rneal... Are you running a HMF slip on?
rneal
07-08-2005, 01:21 PM
Yes... Gt thunder velocity stack, uni filter, stock head pipe, 42 pj, stock carb w/choke, stock needle, 93 or 94 octane fuel... My approximate elevation is 1,250' above sea level.

I run a 165 mj in the winter months.
pead_24
07-08-2005, 06:38 PM
175 main jet does seem a little big