ATV Florida Forum

ok guys still pulling out my hairs with my sons z400. remember i jetted it and lost high rpm. well ive pretty much ruled out carb.ive put two other carbs and still the same. at high rpm it sputters as if the rev limiter kicks in early. ive tried another cdi box AND coil w/wire i got at ebay and same thing.

dont know what to do.


PLEASE HELP..............

I've gotta say that now you just gotta play with the jetting, have you taken a look at the plug at all?  This guy here seemed to have the same problem, read through it and see what you find.  http://www.atvoutdoors.net/topic.asp?TOPIC_ID=10794
I mean really if the spark is perfect, and there's no probelms with the carb, it's gotta be the jetting.  The jet kit is kinda like a baseline kinda, it won't be perfect for every single Z400 in the United States.

we changed the spark plug, and it cant be the jets, rememeber we tried two other carbs with stock jetting, and with jets.

we changed the spark plug, and it cant be the jets, rememeber we tried two other carbs with stock jetting, and with jets.
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Guys at this point you must look some where else.
Leave one of the stock carbs on the bike for now.
Inspect the intake manifold for cracks. This would be my #1 suspect.
Check all wiring in the carb area for pinched or crushed wires.
If your really board you can bring it to my place in Naples and I'll help you tear into it.

But like you know on my bike, when it's running rich and fouling plugs, the plug is black and maybe oily, so that means there's too much deposits on the plug, = too much gas coming in, so I had to go leaner on the jets.  There are all different sizes of jets, not just stock and jet kit size.  I'd have to say the main jet is the wrong size, and depending on how it's running, go up or down with it.  I guess you could try this, ride the bike with the choke on, and see if it gets better or worse anywhere, how it changes.  Put the airlid back on or take it off and see also. 
So is it blubbering like it's getting too much gas when you rev it high?

did you replace the rectifior i think is what its called. i know on the yfz's it goes out and i replaced it and it fixed it. we tried everything and that was the problem. its something you should look into.


its the thing bolted in the middle of my frame next to the shock ressi


(http://i2.photobucket.com/albums/y16/53RAPTOR350/2daee86e.jpg)

#5 on the chart
http://216.37.204.206/alba/Suzuki_OEM/SuzukiATV.asp?Type=13&A=112&B=25

sounds like maybe possable flywheel key broken but only way can see that is if it back fired also heard of the 03's flywheel has several allen screws that can come loose and do some dammage in the stator area you may want to try the tec corner on z400 central just my 2c

1st Question, did you get dirt in the cylinder when removing the spark plug?? Have seen this happen many times, Only takes a couple grains to stick a ring. Compression falls and then the rich running syndrom...

2nd, There is a roll black controller on the left side of the engine that is for the netural and reverse lights and also controls rev limiter in all gears, I have seen these go bad and limit rpm's when not needed, If you check your wiring diagram this can be elimated so there is no rev limit in any gear.

I wouild look into the 1st suggestion first, any questions give a call   

KEN 352-584-0959

Hey Gery,

     Before you burn it let me know, QT might take it off your hands for free!!   lol     ;D

freakk

ILL BUY IT FOR $10 ;D

thanks everyone . i am working tonight(2nd job). so tomorrow when i get home i'm gonna check toy doctors theory. it sounds as if the limiter kicks in so maybe the cdi thinks its in neutral or reverse.

also my son changed the handlebar at the same time i changed the jetting so maybe something happened there(neutral/reverse light). well toy doctor gave me an idea i hadnt thought of(thanks).

i'll keep ya'll posted.

I would also look for a pinched or cut wire in the handle bar area

Freakk

Hey Freakk,

Are you sure you need to be giving directions for repairs??  If memory serves correct, I had to tow you home the other weekend!! ;)

hootchman

Yea yea yea.....  I knew what my problem was. 

I do not know much about sport quads but sounds like the breather hose for the carb is kinked....or clogged....Just a thought....hope it is a simple fix