Yx160 wont idle

[CHINA-BIKE-YO!]

hey ib been playing with this for a few days
done my clearances.....
But i cant get it to idle with the choke off
it will idle rough with the choke on
but when i turnn the choke offf it will rev up then drop back down backfire/pop and then stallll
what can i do i need help!!!!!!!
Thank you

 

[Barnesd09]

Sounds like its too lean. If you turn the chock off and give it some throttle does it still run?
You may need to bump up the pilot jet.
Im in the same situation with my YX160 except having an irk doesn't help, I havent done it yet, but will have it dialed in on Saturday as the neighbours wouldn't like a a reving bike at 9pm.

 

[CHINA-BIKE-YO!]

My pplug is black wich would indicate rich tho wouldnt it....????
And yea if i turn the choke off and keep the revs up it willl keep running but as soon as i drop the throttle it will pop and stalll.... Gay as aids!!
This is a stock bike with no igniton mods
im thinking about taking it to a shop but i wanna learn this stuff

 

[CHINA-BIKE-YO!]

Lol i just got it to a point where i could start it with the choke off......
How can i tell how rich/lean my bike is running??????????????????

 

[Barnesd09]

Yeah, the black plug does indicate a rich mixture but.... you have been idling it with the chock on which makes it rich and has made the plug black, and then when you switch it off it dies. to get a proper plug read the engine needds to be at full oprating temp and have been running in the rev/throttle range for a bit. Revving it wont tell you anything.
the popping/crackling is a lean mixture exploding in the pipe.
Farting/coughing is a rich.
Up the jets just one number and see how it goes.

There are also a few threads on here that teach you what to look for when tuning a carb.
There is a thread where people have posted thier jetting on different bike and carbs that you can use as a starting point.

For me, I have an oko26 on a stock yx160 that was jetted for a Daytona 125. It has a 35 pilot and 105 main but the main is too big and the pilot too small, So I'm goin gto drop it back to 100 main and up to 36 pilot, and if its still not enough I change them again.

 

[CHINA-BIKE-YO!]

By 1 number what are the incriments ?? Umm i dont think the pilot jet had a number on it...... I did looktho..... The main was a 105. But no number on the pilot

 

[Barnesd09]

If your going to embark on this to learn, its best to get a jet kit, with the numbers stamped on them
For mikuni jets the will usualy be 15 - 25 in 2.5 increments and mains 90 - 105 in 2.5 increments
Keihin jets will be 34-39 in single increments and 90 - 110 in 2 increments for a 26mm and 130 range for bigger carbs.
Without knowing what jets you are running and are unable to change with different ones you will only chase your tail, become frustrated and in the end give up because it wil never work.
Its like typing on a keyboard without the letters on the keys and having never seen a computer before.
DHZ sell good jet kits that are reasonably priced and will come in the mail in a couple of days.

 

[CHINA-BIKE-YO!]

kk sweet bro i just dropped the needle to the very bottom .....
if i put my hand over the carby in let and restrict flow it will start and roughly idle .......
also would a leaky inlet manifold gasket make any major differance........
runs better with choke off ie revs lower with out stalling with choke off but not quite idleing
so would i add more fuel or slow the air flow........ and how do the air adjust screws work on the carby
cheers and thanks 4 the help!!!

 

[CHINA-BIKE-YO!]

plastic bag round da air filter??? lol with holes??

 

[Barnesd09]

kk sweet bro i just dropped the needle to the very bottom .....
if i put my hand over the carby in let and restrict flow it will start and roughly idle .......
also would a leaky inlet manifold gasket make any major differance........
runs better with choke off ie revs lower with out stalling with choke off but not quite idleing
so would i add more fuel or slow the air flow........ and how do the air adjust screws work on the carby
cheers and thanks 4 the help!!!

I'd be putting the needle back to the middle clip and working on the idle first, then move to the needle then to the main jet. Each part effect the mixture at different throttle opening positions. For idle all your woried about is the pilot jet and air/fuel screw.
By putting you hand over the inlet, you are doing the same job as the choke.
A leaky manifold... Yes, is generally causes the engine to hunt [unstable idle speed] and makes the mixture lean and engine get hot.
I'd be adding more fuel, ie. bigger jet, But if you know what your really doing, float bowl level can be adjusted [but for a beginer just leave it.
Can't say as different carbs are different, which carb do you have???

 

[CHINA-BIKE-YO!]

i have a molkt carby do u need to know what size coz ill go take it off and measure the inlet....???
that makes a lot of sense the needle is affecting half throttle isnt it...
im sure i got some gasket paper here some where ill make a new gasket (lotsa experience) lol
how hard is it to adjust the float ie.bend the bracket it sits on even ...?? is it that simple .. how far would i take it ........ this would increase/restrict fuel wouldn't it?? so id wanna bend it up u bit..??
thanks 4 puttingg me on the right track!!!!

 

[Barnesd09]

There are 2 molkt setups in this tread http://www.miniriders.com.au/carby-tuning/24570-carby-settings-your-bike.html
I'd just leave the floats alone, as it changes everything and it will set you back to square1.
Stock it should work ok, give it a clean.
and if, i mean if you do decide to play with the float levels they ar measured by turning them up side down and measuring from the edge to the top of the floats (the bottom part when the right way up)

 

[CHINA-BIKE-YO!]

im gunna replace the gasket and try again if nothing....
im gunna take my pilot jet out take it to a shop and get somthing bigger and put the needle back to middle
if that dont work i think i might have to take it to a shop.... but i really dont wanna

 

[CHINA-BIKE-YO!]

cheers bro bike is running sweet no ned 4 jets yet(havent been 4 a ride
done the gasket and she idles sweet revs right thro sounds good!!!!!!!
+2 bro big help

 

[CHINA-BIKE-YO!]

theres a smakk tapping in the topend very small and it goes with the revs .... what cold it be... is it normal....???

 

[Barnesd09]

does it go away or get better once the engine is up to full temp?
If it does, its usually valve clearance.
If it doesn't..hmmmm. I hate to suggest, but could be detonation.
But most likely you have too much clearance.

 

[wogtaz ryder]

get a oko26mm plug and play ........ usually

 

[CHINA-BIKE-YO!]

ill wait till it cools down and check em.....
im also experiancing low to mid throttle bogging ...almost to the point of stalling slip the clutch and off i go
is that a lean pilot jet???

 

[Barnesd09]

ill wait till it cools down and check em.....
im also experiancing low to mid throttle bogging ...almost to the point of stalling slip the clutch and off i go
is that a lean pilot jet???

Now play with the needle, you will find it probably is a touch lean. If when you try it and it get worse, move it back the other way.
But raise the needle 1 groove. So the clip gets moved down.

 

[CHINA-BIKE-YO!]

Cheers bro!!
ILL LET YA KNOW!!!!!