Air screw adjustment?

blaster003

blaster003

Member
May 13, 2014
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ok so I started up my bike today and it was idling higher than usual when I reved it the idle it would hang for a little then after 30 seconds it goes down then down lower until it stalls I had my airscrew out 1.5 turns and my main jet is 280 when I turn my air screw all the way in i idles perfect and revs the best and idles down fast do I need to put a bigger main in it?
 
the airscrew has nothing to do with the main jet,
it controls airflow thru the pilot jetting circut only which determines idle to 1/4 throttle

is this a stock carb on a stock cylinder ?
then i would say no to the larger pilot.
the stock 32.5 pilot has proven to be spot on for almost all situations, temps and elevations
normally the airscrew under 1/2 turns out does mean you need a richer pilot,
but i'd suspect a partially clogged pilot.
when was the last time you ran it ?
cleaned the carb ?
could be just dried oil partially clogging the pilot.

if this is a larger carb than stock and it's clean, then yes you may need a pilot jet increase.
plug chops will determine your main jetting
 
It's a stock carb with an fmf it idles perfect with the air srew all the way in but as soon as I turn it out it stalls
 
blaster003 said:
It's a stock carb with an fmf it idles perfect with the air srew all the way in but as soon as I turn it out it stalls
Click to expand...


the airscrew in suggests a larger pilot, but not if the pilot is partially clogged with dirt or dried oil.
try properly cleaning the carb and try the airscrew adjustment again after that....

http://www.blasterforum.com/threads/how-to-clean-your-carbureutor.254/

check your reeds and float level while you have the carb out for cleaning
http://www.blasterforum.com/threads/float-heights-and-how-to-adjust-them.50565/
 
Turning the air screw in fully means that there could be an air leak.

Leak test is in order!
 
Last edited:
Ok so I cleaned the carb it still revs the quickest and idles highest with the airscrew turned all the way in do I need to get a bigger or smaller pilot jet or do I need to do something else?
 
It was about 35 outside today the last time it was jetted was during the summer which was about 75 to 85 when I would take off with the airscrew 1.5 turns out it would bog a little and when I turned it all the way in it takes off fine and runs a lot better but idk what I need to do now
 
blaster003 said:
If I get different size pilot jets will I need to get different size main jets?
Click to expand...

no to bigger mains because of a pilot change.
yes to bigger main if a plug chop says so

the airscrew adds air to adjust the fuel/air mix of the pilot jet circut.
turning the screw in adds less air, richening the mix
if under 1/2 turn out to achieve highest idle, you need a larger pilot jet. go 1 size bigger
IF....all else is good, including passing a leakdown test

did you check the float height ?
 
Did you delete the tors and are you running oil injection or no? I agree with awk,, your symptoms say larger pilot but the stock pilot covers allot of different variations of mods without needing to be changed.. If leak test comes out good and float height is correct than change pilot.. Are you sure stock blaster pilot is in there now? and that it is a stock blaster carb and not a banshee carb?
 
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