carb help???

[batz3]

well i am just getting into working on quads and riding quads and i am trying to set up my bike to be as perfect as it can be. now when i start my bike it tends to backfire and seems like the carb is jumping like it hessitates. now i have been reading the manual and i am trying to get my bike to the proper idling speed. now my question is it says to turn the piolet air screw until it is lightly seated...what does this mean?? and help with this will help, cause to me the bike is idling to high and sometimes shuts off while in idle.

 

[klutchbuster350]

their should be a black idle knob on the carb you should be able to turn to adjust the idle.

 

[griff]

In order to adjust the idle properly, make sure the engine is fully warmed up.

All 4-strokes with CV carbs are gonna cough and spit a bit when cold (choke or not). Get it up to operating temp, and adjust from there.

Edit: The manual says to adjust the pilot A/F screw?? Which manual exactly? If a jet-kit, didnt they provide a base-line setting for everything?

 

[batz3]

first off let me tell you i am getting this information out of the yamaha supplementary service manual and i will write exactly what is say so i can get some help..


1 start engine and let it warm up for several minutes
- this one to me is clear
2. attatch inductive tachometer to the spark plug lead.
- this is clear to i just need to buy the tool
3. check engine idle speed with tool.
4. adjust engine idling speed
5.(now here is what i don't get) turn in the pilot air screw until it is lightly seated
6. turn the pilot air screw for the specified number of turns
7. turn throttle stop screw in or out until specified idling speed is obtained.

 

[ratchracing]

its a screw on the bottom of the carb in front of the bowl. You turn it in all the way then turn it out 2 1/2 turns, then adjust in 1/4 turns until you have the proper air/fuel mixture

 

[02yfm350]

dude this is happening on my wariror. I always let it warm up for a good 1 to 2 minutes and I was telling my dad I think its idiling too high. Could this be effecting my throttle response? cause whenever its revving low in a gear and i punch it, it just doesnt give power right away. i have to feather it. but under high reving in will give good throttle response. I'm definatly not familiar with anything much on a quad so I would have to get my dad to adjust it. Is the pilot air screw or whatever you need to adjust hard to get to?

 

[dave76]

If it's idling too high after it warms up, just turn the idle screw down.

 

[ratchracing]

dude this is happening on my wariror. I always let it warm up for a good 1 to 2 minutes and I was telling my dad I think its idiling too high. Could this be effecting my throttle response? cause whenever its revving low in a gear and i punch it, it just doesnt give power right away. i have to feather it. but under high reving in will give good throttle response. I'm definatly not familiar with anything much on a quad so I would have to get my dad to adjust it. Is the pilot air screw or whatever you need to adjust hard to get to?

if your having throttle response problems its most likely the accelerator pump needs to be adjusted properly

 

[Guest]

IT coul be the Jet he installed also. When i installed mine i tried the 152 and it coughed alot, expically on top end while riding. I went to the 148 and it clear'd up alot but still done it so i dropped down to the 146 and it completely stopped.

The issue for mine was that the 152 - 150 - 148 altitude requirement's.

 

[02yfm350]

well i'll try the idiling screw, and if it doesnt help the throttle response i'll get after my dad to take off the carb and check the accelerator pump. but i doubt that would happen cause my dad is just too lazy and he wouldnt let me do it myself and I also have the stock exhaust

 

[griff]

You should only be adjusting the a/f screw for jetting purposes. That circuit will be kinda noticable for part-throttle response. All you need to do is adjust it for whatever the setting is your given base-line, and then just make sure the idle (regardless of speed), doesnt hang or surge.

So adjust for jetting 1st, then adjust for idle speed when done (and not before)

For example....

If idling, and you rev the engine up real quick, and the idle stays high for a little bit before settling down further, then you are lean on the a/f screw. If its surging, probably still lean, and or you have a vacuum leak on the intake boot. To richen, turn the screw out (counter-clockwise), quarter turn at a time.

If its too rich, it will stumble and bog down momentarily when you try to rev up the engine. Turn the screw in (clockwise) to lean it out.

Once throttle response and idle behavior seems good, then adjust the idle speed via the black knob already mentioned.

Hope that makes sense.

 

[batz3]

need help with a warrior i am new to this stuff so all the lingo doesn't make sense to me yet i would like visual.

 

[ratchracing]

theres a good thred in the tutorials page about the breakdown of the carb and how the jetting works together and it has pictures for the imagination impared....... do a search