400ex rev problem NEED help QUICK

[400exwheelieboy]

hey guys i just got my 400 runnin and put a slip on on it and rejetted it to 164main needle on 3rd notch and for sum problem when i rev it it starts cutting off at 4000-6000 rpms (not normal) is it my cdi box or is it the jetting? also when i was catwalking it ,it didnt even have the power to lift up in 2nd gear(not normal)

[JOEX]

Originally posted by 400exwheelieboy
hey guys i just got my 400 runnin and put a slip on on it and rejetted it to 164main needle on 3rd notch and for sum problem when i rev it it starts cutting off at 4000-6000 rpms (not normal) is it my cdi box or is it the jetting? also when i was catwalking it ,it didnt even have the power to lift up in 2nd gear(not normal)
164 main jet sounds too rich for just a slip on. Is it a Keihin jet or a Dyno jet?

Air filter? Air box lid on or off?

[400exwheelieboy]

dyno jet, stock filter (lid on)

[400exwheelieboy]

it feels like its the rev limiter though. theres no black smoke or any smoke coming out its clean air. and could it be a problem if the battery is dead?

[JOEX]

Originally posted by 400exwheelieboy
dyno jet, stock filter (lid on)
You're way too rich IMO.

A 146 Dyno jet should be close.

[JOEX]

Originally posted by 400exwheelieboy
it feels like its the rev limiter though. theres no black smoke or any smoke coming out its clean air. and could it be a problem if the battery is dead?
That's what a rich condition feels like.

I supppose it could be an electrical issue but since you just changed the air and fuel system i'd look there first.

[400exwheelieboy]

damn well my dad says that the jetting is fine bcause there is no black smoke coming out .

[400exwheelieboy]

well shall i make a vid for you too watch?

[JOEX]

Try putting the stock jet back in and see how it runs. Since you still have the stock air filter I don't think there will be a problem.

[casey_lamm]

I agree...im running a dynojet kit with a slip on and k&n and didn't need larger then 155 or 156...


Originally posted by JOEX
Try putting the stock jet back in and see how it runs. Since you still have the stock air filter I don't think there will be a problem.

[450rJam]

its too rich

it will only blow smoke if its really really rich

you prob. have good bottom end though, and you only get to use 1/2 of each gear before you have to shift

[400exwheelieboy]

no my bad guys the jet is actaulli a 146

[casey_lamm]

humm...well in that case there might be a problem :)
Originally posted by 400exwheelieboy
no my bad guys the jet is actaulli a 146

[JOEX]

Originally posted by 400exwheelieboy
no my bad guys the jet is actaulli a 146
Well, that changes things...

You're using a dyno jet, correct? I belive they use an adapter as well, assuming that's in place and you're using the needle that came with the kit.

Was it running fine before the slip on and jetting?

[REDRIDDER]

did you take off your car at all?

[400exwheelieboy]

its a dyno i used the main jet adapter of course and im not sure if it ran fine because when i put the rest of the needed parts together and situated it didnt even have a jet in the carb. so it didnt even run. i had to replace timing chain,piston,valves and the jets .

[400exwheelieboy]

and of course i took off my carb becuz i had to replace the jets.

[400exwheelieboy]

cld it be that the cdi is busted?

[400exwheelieboy]

well damn with the respect of joex u guys dont seem to be helping me.

[450rJam]

you need to tell us the whole story so we can give you good advice

is this a basket case where you get a bunch of used problems and try to make a motor out of it?

what do you mean by "I put the rest of the needed parts together?"
and you didnt have a jet in the carb ?
who replaced the timing chain/piston/valves etc ?
why did they need replaced ?
you may have several problems
valves out of adj.(did you use new or used parts)
timing off ? how did you set it and have you checked it since?
did you bore/hone the cylinder? rings in correct?
it could be in the cdi also

you may need alot of help with this one but if you can give us all the correct information it will help us help you

[400exwheelieboy]

alright my dad is a pro car mechanic,we replaced the valves because they were bent. we were moving the timing chain when all of a sudden we saw that the timing chain was bad. so replaced the timing (all the parts we replaced are new ) so we got the parts in (timing chain,valves,etc. ) found out the timing info timed it and it started and wldnt run without the choke and wldnt rev at all.(if u touched the gas it wld die.) so we took apart the carb knowing it was a fuel problem,checked out everything and saw that there was a jet just laying in the spot where it needs to go.(not screwed in) and it was the wrong size(main170) way off. so we got a dyno jet kitand replaced the 170 with the stock 142main and we started it with the stock exhaust on and it didnt rev high(same as now) so the next day my pipe had came in. so i installed it and went straight to the jet manual to see what jet it needs for the aftermarket exhaust. so i see that it needs 146main with apps under 5000feet so i installed it and installed the needle included also (clip on 3rd notch with the small washer on top of the clip)and we put the pilot screw on 3.5 turnswe put it all together and start it .and i drive it down the road(im the test driver lol) i punch the gas and it starts boggin so i turn around pop the clutch and try to wheelie back to my house and it wont even have the power to lift up in 2nd gear! so back to the drawing board so yeah guys please help me out i need HELP!

[450rJam]

why was the valve bent ?
have you done a compression check?

[400exwheelieboy]

yeah the retarded first owner i guess way over revved it and it bent the valves and yea wer did a compression check and we are good.

With the stock rev box you can sit the 400ex on the rev limiter all day and it will run perfectly fine. I'm serious you can bounce it off the rev limiter forevr and everything is perfect. But if you have a different rev box that adds 1000rpm or anything like that then you can bend valves or blow up your motor

[blasterandy]

It still sounds like fuel deliv. have you tried taking the air box lid off and seeing if it runs n e better. If so it is a fuel prob.
Try that... i doubt its a cdi problem. Did you break the new piston rings in... or did you just go out and start bashing on it... if so you may have just screwed it right there.

[400exwheelieboy]

no we did perfect break in and its not a fuel problem because we started to rev it and my dad sprayed starting fluid in it and it did the same thing. also i tried without the lid and still nothing.

[project400ex19]

check your choke too...It's simple but i've done it once. What a stupid headache.

[blasterandy]

Your other option is take it to a shop and have them diag. the problem could your timeing be off, also have you changed your spark plug.

[400exwheelieboy]

nah i havent changed my spark plug but if its the spark plug fouled wldnt it not start?:confused: :confused:

[kyexgirl]

Originally posted by 400exwheelieboy
nah i havent changed my spark plug but if its the spark plug fouled wldnt it not start?:confused: :confused:

not always. it doesnt have to be completely fouled. the spark from it can be weak causing the fuel to not combust properly. it could start, but run like crap.

[kyexgirl]

Originally posted by 400exwheelieboy
it feels like its the rev limiter though. theres no black smoke or any smoke coming out its clean air. and could it be a problem if the battery is dead?
ok i have read all the posts here and think i'll throw my 2 cents in. one of your posts ask if it could be caused by a dead battery. and another said you had to put a lot of stuff together. the way its acting could be a couple of things i believe were not mentioned. first, when you got into the carb, did you give it a thorough cleaning. i dont mean stick it in some kind of solution and rinse it out. if it has sit for a while before you got it the carb could be gummed up somewhere. you can boil it out or take some fine, stiff wire and rod out all the holes in it. then take some wd-40 or something and flush out the holes. you will have to take the bottom end of the carb completely apart to do it. some carbs have a screen under the float needle and that could be partially stopped up as well. the other thing is the dead battery. if the charging system is good, that shouldnt be the problem. but if it is going bad, you are not getting enough juice to run the bike with a dead battery. it will act like a semi- fouled plug. also dont run it long with a dead battery, that can cause your charging system to go bad. hope this helps

[blasterandy]

the thing about the alt that ky said is true but i don't see that being the problem as the are pretty reliable, and they normaly just go and don't start slowly deteriorating. Dpr9z-dpr8z i have about 20 new ones so if you come over to my house il give ya one to put in just to say i told you so. :D Just go pick one up and see. I bet its the spark plug. The 9z is a hotter plug better for low gear trail riding and high rpm applications. 8z is good for relaxful riding... personally i use witch ever one is in stock. :D but prefer the 9z they seem like they don't foul as much... my 400 use to be pretty bad on plugs.

[400exwheelieboy]

dood i went to the store taking your word for it thinkin it was just the plug so i bought 10 9z's for 22.50$ and the bike still has the same problem. thanks alot!!!!:ermm: well i guess the only other thing it cld be is the rev box is bad or its the coil so im gonna order both and keep yalll posted.

[JOEX]

Originally posted by 400exwheelieboy
dood i went to the store taking your word for it thinkin it was just the plug so i bought 10 9z's for 22.50$ and the bike still has the same problem. thanks alot!!!!:ermm: well i guess the only other thing it cld be is the rev box is bad or its the coil so im gonna order both and keep yalll posted.
Why did you buy 10:confused:

[400exwheelieboy]

cuz i figured well while im here might as well get em now so i dont have to come back. and i thght cuz so many peepl said it cld be the plug that i got sum.

[450rJam]

well make sure you get a dozen coils so you will have a life time supply of those also

dont hack on the guys trying to help you, it could be several things and the plug is cheap to check (if you dont buy bulk)

[QuadManiac]

Umm, take 9 plugs back?

Seriously, does it bog immediately when you reach, about 3/4 throttle, or does it take a few seconds at high throttle to bog?

Does the 'bogging' follow throttle position, or engine RPM? In other words, at 1/3 throttle in 1st gear on flat terrain, can you run all the way up in revs without a bog or does it do it anyway, once the RPMs get up high? (trying to isolate ignition from fuel problems here)

A suggestion: go back to stock exhaust and jets until you get this worked out. With the aftermarket parts, you are compounding your diagnosis problems.


Good Luck!

[QuadManiac]

Originally posted by 400exwheelieboy
well i guess the only other thing it cld be is the rev box is bad or its the coil so im gonna order both and keep yalll posted.

NO..... There are at least 10 or 20 more things it could be.

If you continue to troubleshoot by buying a new component and installing it without any real diagnosis, you can and very well might spend more than the bike's worth trying to fix the problem...

Spell out the problem carefully and logically, and let the team here try to help you DIAGNOSE it. Else, happy shopping.

Good Luck!

[400exwheelieboy]

Sorry I haven't kept you guys posted... well I did diagnose the problem and I repaired it.. It was tha coil,and or the rev box... one was junk. But anyways now I gotta chop sum stuff off my bike to put my new motor in (blew the old one) . Cuz sum1 welded the swingarm pivot bolt to tha frame!!! So yea.

[Exrider434]

check the electrical, my buddys got an 05' 400ex and when his lights are on it bogs because there is no battery power to the lights cuasing the motor to have to make up for the lost power in the lights. If the lights are off it will run fine.