engine stall when blipping the gas

[promisc]

When i blip the gas from idle to WOT(at neutral) and keep it WOT, it completly stall. if i blip it from the 1/8 to WOT or idle to WOT but slower, its ok.. does it means its too lean so only air comes in (not enough air restriction so no fuel raise in the mj...) or too rich so the plug get fooled and stop to spark?

Got a 42pilot(keihen), 160mj Dyno, needle on the 4th groove from the top and K&N filter w/o lid.

Also, white smoke when the engine is cold is normal ?
The engine doesnt burns oil. I use Motul or Hypertech.

[zephead400ex]

Is the quad warm when you experience this? What does your plug look like?

[promisc]

warm but not like after a ride.. its like 2-3min idleing..

i checked the plug after a long ride.. its light brown

i miss to say that at idle, its runs without stalling but it skips and the rev is not stable.. the rev goes faster.. then slower.. miss some strokes etc. it looks like i have a pilot circuit problem.. i tried to adjust the fuel screw but no big change

[cals400ex]

it could be a lot of things. you need to make sure it is up to FULL temperature. also, once you start modding the bike a bit you really really have to mess and tweak around with jetting to find a good setup for your bike, the elevation your at, the humidity, the temperature outside, etc.

it may be tough to get rid of a miss when quickly flooring it from a dead stop.

[KASCHAK]

haha.. just soved taht problem..
my plug was golden brown too..
try turning your idle mixture screw just behind the idle screw. and move the clip on the need down one position..
helpe alot makes it run a ton better. and now a darker chocolate color plug

[KY Woods Rider]

The only way you're really going to be able to tell anything about it is to take plug readings and riding it when it's fully warmed up.

If you're sitting in neutral, especially with an engine that isn't up to full temp, and you try to go directly from idle to WOT as fast as you can punch the throttle, you're going to have some problems. Under those conditions, it's normal for the motor to stumble and cough once or twice and then start revving. If it's not warm, you may even stall it completely. When you open the throttle so quickly, the engine needs more fuel to work with, but then it suddenly receives a huge dose of fuel and it can't handle that transition period very well. The problem is that much worse when there's no load on the engine (neutral) and it's a 4-stroke with an accelerator pump in the carb.

Even while riding, if you let the engine go down close to idle (near stalling) and you punch the throttle wide-open as quickly as you can, the same problem can occur.

Assuming the engine is up to full temp, if it does it when you have the RPM up pretty good and punch it wide-open, when you go from idle to wide-open but it in a slower and more gradual motion, or it does it under normal riding conditions when the RPM is up a bit and you go from about 1/8 throttle to WOT, then you have a problem. It can be caused by either a rich or lean condition, you just have to go by plug readings and if you have some experience at it, you can usually tell whether it's a rich or lean condition just by seat-of-the-pants feel.

If the smoke at start-up is white without any hint of blue, it's most likely condensation in the exhaust pipe. It could possibly be a bit of raw fuel if it's only doing it when you suddenly hit the throttle while the engine is still cold. If it does it just a bit when at idle or when you barely rev the motor, it's just condensation.

[promisc]

Originally posted by KY Woods Rider
The only way you're really going to be able to tell anything about it is to take plug readings and riding it when it's fully warmed up.

If you're sitting in neutral, especially with an engine that isn't up to full temp, and you try to go directly from idle to WOT as fast as you can punch the throttle, you're going to have some problems. Under those conditions, it's normal for the motor to stumble and cough once or twice and then start revving. If it's not warm, you may even stall it completely. When you open the throttle so quickly, the engine needs more fuel to work with, but then it suddenly receives a huge dose of fuel and it can't handle that transition period very well. The problem is that much worse when there's no load on the engine (neutral) and it's a 4-stroke with an accelerator pump in the carb.

Even while riding, if you let the engine go down close to idle (near stalling) and you punch the throttle wide-open as quickly as you can, the same problem can occur.

Assuming the engine is up to full temp, if it does it when you have the RPM up pretty good and punch it wide-open, when you go from idle to wide-open but it in a slower and more gradual motion, or it does it under normal riding conditions when the RPM is up a bit and you go from about 1/8 throttle to WOT, then you have a problem. It can be caused by either a rich or lean condition, you just have to go by plug readings and if you have some experience at it, you can usually tell whether it's a rich or lean condition just by seat-of-the-pants feel.

If the smoke at start-up is white without any hint of blue, it's most likely condensation in the exhaust pipe. It could possibly be a bit of raw fuel if it's only doing it when you suddenly hit the throttle while the engine is still cold. If it does it just a bit when at idle or when you barely rev the motor, it's just condensation.


Thanks alot, im reassured for both of my questionning... :)
ill never try to adjust my bike without riding it first to warm it correctly..

[BLACKeR]

at idle, its runs without stalling but it skips and the rev is not stable.. the rev goes faster.. then slower.. miss some strokes etc. it looks like i have a pilot circuit problem.. i tried to adjust the fuel screw but no big change

if you try the other stuff and still have a problem, you might have an air leak. the climbing revs withought you giving it gas, sounds like an air leak to me. would also goof up your jetting.

[zephead400ex]

Originally posted by BLACKeR
if you try the other stuff and still have a problem, you might have an air leak. the climbing revs withought you giving it gas, sounds like an air leak to me. would also goof up your jetting.

This is true too. When the quad is running, spray carb cleaner around the boot, if the engine revs, there is an air leak. However, I have had similar problems and this was the fix for mine.


Originally posted by KASCHAK
try turning your idle mixture screw just behind the idle screw. and move the clip on the need down one position..
helpe alot makes it run a ton better. and now a darker chocolate color plug