what is this a symptom of?

[bigboi11]

If I go half throttle everything is ok. When i try to punch it, it starts to sputter like its going to cut off. I don't know which way to turn which needle to try and fix this problem. Any help I would love to have.

 

[jon2]

How long does it take to die when you pinch it? Best place to pinch is right at the carb. How does the idle act? Does the idle rev up?more info.

 

[ImBroken]

Usually when you get a sputter, it means it's running a bit rich. When it cuts out clean, it's usually too lean.
I would say, start by leaning out your HSN an 1/8th of a turn at a time and see what happens.
If it gets worse, then do the complete opposite of what this moron just told ya...

 

[CorradoPsi]

what engine do you have? is it a 2 or 3 needle carb?

 

[bigboi11]

I have a hyper .21 8 port. I i have a hsn, lsn, and a midrange that i'm not supposed to touch that i think i did. when i pinch it it takes about five secound to go out and it revs up and dies gracefully. Thats what made me think that my lsn was good.

 

[CorradoPsi]

ok, do you know the difference in sound of a lean bog, and loading up? loading up is kinda blubbery, and lean bog is raspy. drive your car at mid throttle for a bit, like at least 6 seconds. then punch it, and let us know which it is. because it sounds to me like your mid needle or HSN is out of tune.

also, the engine that you have is very prone to air leaks. have you gone through and sealed the backplate and carb?

 

[bigboi11]

When i punch it, it is a blubbery bog. I think it might be the mid cause i touched it even though i wasn't supposed to it was an accident. I will check for leaks I just put a new case on it cause i cracked the other one on my first crash ever. How's that for luck.

 

[CorradoPsi]

try leaning out your HSN first. then let me know how that works for you. make sure at top speed it still has a good trail of smoke and it doesn't sound lean or like its over reving.

 

[flash]

the mid range needle should be flush with the carb body. i would say if the high speed is set right (per info from corradopsi) then you should try leaning the msn just a tad at a time til it quits. from factory settings it should not be turned more than 1/4 turn either way.
every mill I've had with the third needle was set rich from the factory. the v-spec was the absolute worst. it took over 1/4 turn in to get it just right.

 

[CorradoPsi]

hah, flash you think your v-spec was bad. mine needed the MSN leaned out a full turn.

for proper MSN tuning:
you need to turn the LSN an EQUAL AND OPPOSITE amount to whatever you adjust on the MSN. if you fail to do this, you will screw up your LSN setting in the process.

example:
if you lean the MSN by 1/4 turn, you need to richen the LSN by 1/4 turn.

only tune your MSN after both your HSN and LSN are properly set. failure to do so WILL totally mess up all your settings. to check for MSN tune, you need to drive at part throttle for about 5-6 second then punch the gas. if it bogs, lean the MSN by 1/8th of a turn. repeat until its snappy from mid throttle. if it lean bogs the first time you try it (stutters, sounds raspy, very little smoke, then takes off) then richen the MSN by 1/4 turn until its snappy.

 

[bigboi11]

how can I tell the difference between when it is bogging from the msn and the lsn.

 

[CorradoPsi]

do the pinch test to make sure your LSN is set.

get the motor up to operating temp, with the car off the ground rev it to clear it out. once its cleared out let it come down to idle then pinch the fuel line next to the carb inlet. it should take 4-5 seconds for the engine to rev up and die. if it takes longer, the LSN is too rich. if it takes less time or it just dies and doesn't rev up, the LSN is too lean.

once your LSN and HSN are set, you can start adjusting the MSN.