Trying to jet my Airstriker carb........

[fearlessfred]

A brand new prejetted carb should not need all this work to run proper,a 40 sj is crazy .something else is wrong

[Jimbo45]

A brand new prejetted carb should not need all this work to run proper,a 40 sj is crazy .something else is wrong

I know, right!?  But, I can't imagine what else could be wrong.......

[Skeans1]

They didn't happen to modify the fuel circuits in the carb did they?

[fearlessfred]

I know, right!?  But, I can't imagine what else could be wrong.......

reeds have already been mentioned and you said they were good.My next guess would be bad stator and Im only drawing from my own experience .had a friend torch a brand new piston from a bad stator,he kept leaning it out to get it to run right and it ran right for a few second.If you had one you could borrow ,it would be nice.

[Jimbo45]

They didn't happen to modify the fuel circuits in the carb did they?

I don't think so.  Nothing like that was mentioned, anyway.

[Jimbo45]

reeds have already been mentioned and you said they were good.My next guess would be bad stator and Im only drawing from my own experience .had a friend torch a brand new piston from a bad stator,he kept leaning it out to get it to run right and it ran right for a few second.If you had one you could borrow ,it would be nice.

But it runs so solid, I can't imagine the stator is bad. Starts right up everytime I try, like the 2nd or 3rd kick on choke, and runs and idles strong.  WOT acceleration is very strong too.  The stator is a ricky stator, with not a whole lot of time on it.

I have got it in the ballpark now, it just is odd that the idle and main circuits need to be at relatively lean settings, when the needle likes to be at a really fat setting, compared to what I am seeing others run.  I don't get it.

The small pilot doesn't really surprise me so much, since I am not running a hi flow open airfilter.  I have the stock airbox covered with an outerwears box cover (probably is kinda restrictive, maybe as much as just running the lid on and a snorkle), and a fairly heavily oiled uni filter with belray oil.  If I were running an open element K&N, like some guys, I suspect a pilot closer a 50 would be needed.  What is wierd with the pilot, is that the air screw is not easy to find a sweet spot.  I start at 1.5 out, and back out until the rpms quit rising, and that is where it runs best, but if I cotinue another turn or so, it really doesn't start to slow much from a lean condition. It could be that the particular sweet spot is at about 2.5 turns out with the 42 pilot.  I will put the 40 pilot in, and see if it shows a more definite sweet spot, at around 1.5 turns out, hopefully.

[fearlessfred]

They didn't happen to modify the fuel circuits in the carb did they?

Im pretty sure Carla buys them from sudco prejetted  and marks them up ,who knows though ,for a while there he was selling carb towers to anyone that had any kind of carb problem,until he ran out of stock

[fearlessfred]

But it runs so solid, I can't imagine the stator is bad. Starts right up everytime I try, like the 2nd or 3rd kick on choke, and runs and idles strong.  WOT acceleration is very strong too.  The stator is a ricky stator, with not a whole lot of time on it.

I have got it in the ballpark now, it just is odd that the idle and main circuits need to be at relatively lean settings, when the needle likes to be at a really fat setting, compared to what I am seeing others run.  I don't get it.

The small pilot doesn't really surprise me so much, since I am not running a hi flow open airfilter.  I have the stock airbox covered with an outerwears box cover (probably is kinda restrictive, maybe as much as just running the lid on and a snorkle), and a fairly heavily oiled uni filter with belray oil.  If I were running an open element K&N, like some guys, I suspect a pilot closer a 50 would be needed.  What is wierd with the pilot, is that the air screw is not easy to find a sweet spot.  I start at 1.5 out, and back out until the rpms quit rising, and that is where it runs best, but if I cotinue another turn or so, it really doesn't start to slow much from a lean condition. It could be that the particular sweet spot is at about 2.5 turns out with the 42 pilot.  I will put the 40 pilot in, and see if it shows a more definite sweet spot, at around 1.5 turns out, hopefully.

air screw should only be opened exactly at the point were the highest idle is found,so that requires going past that point and returning to it,sounds like that's what you are doing

[Jimbo45]

air screw should only be opened exactly at the point were the highest idle is found,so that requires going past that point and returning to it,sounds like that's what you are doing

Yeah, that is what I am doing.  I guess I am comparing it to the fuel screw on 4 strokes, which I have much experience.  On those, the fuel screw is very picky, one way or the other.  An eight turn to far in, engine slows, and eighth turn too far out, it slows.  On this R, I can back out the airscrew to a point where the rpm is the highest, and then back it another turn farther, without the engine rpm changing.  But yes, I am putting it back to a richer setting, where the idle just begins to slow a bit from the highest idle.

[Jerry Hall]

................. My next plan is to shim up the DGH needle with some stainless number 4 washers, the distance of another clip position or two.

Be careful, raising the needle like this may cause the needle to pull out of the needle jet at full throttle causing the throttle to stick wide open!!!!!!!!!!!!!!!!!!


A DCH in the top clip position will give you the same mixture vs throttle position as the DGH in the bottom position you are now using.

A DEG in the middle clip position will be a little richer in the 0 to about 1/2 throttle position and the same as the DGH in the bottom position from about 1/2 full throttle position.  

You need to invest in a hand full of different needles so that you can make changes and learn how these carbs really work.  This is the only way you are going to learn how to tune these carbs.  There are over 125 needles that fit this carburetor.

I would recommend that you put these needles in your tuning kit.
DDE, DEF,  DEG,  DEJ, DEK,  

If one of these needles does not make your engine run correctly you probably have other problems with your basic engine package.

[fearlessfred]

Be careful, raising the needle like this may cause the needle to pull out of the needle jet at full throttle causing the throttle to stick wide open!!!!!!!!!!!!!!!!!!


A DCH in the top clip position will give you the same mixture vs throttle position as the DGH in the bottom position you are now using.

A DEG in the middle clip position will be a little richer in the 0 to about 1/2 throttle position and the same as the DGH in the bottom position from about 1/2 full throttle position.  

You need to invest in a hand full of different needles so that you can make changes and learn how these carbs really work.  This is the only way you are going to learn how to tune these carbs.  There are over 125 needles that fit this carburetor.

I would recommend that you put these needles in your tuning kit.
DDE, DEF,  DEG,  DEJ, DEK,  

If one of these needles does not make your engine run correctly you probably have other problems with your basic engine package.

Jerry, have you ever had to use a 40 pilot in a 38 a/s

[Jerry Hall]

I do not recall using a 40 but I have used a lot of 45s and 48s.  To make the engine idle correctly and not have an off idle lean hesitation when using pilots in the mid to low 40s, you may need to use a richer slide and or needle that has a smaller diameter where the needle is a constant diameter before the taper starts.  

Most guys do not want to spend the money for different slides and needles so they usually end up having to use a pilot that is in the mid to upper 50s.


Having to use a very small pilot to make the engine idle when using some popular needles like a DGH or DEJ may be a sign that your needle jet is worn and letting a lot more fuel flow between the needle and needle jet at closed throttle than a new carb would do with the same needles.

[Jimbo45]

Be careful, raising the needle like this may cause the needle to pull out of the needle jet at full throttle causing the throttle to stick wide open!!!!!!!!!!!!!!!!!!


A DCH in the top clip position will give you the same mixture vs throttle position as the DGH in the bottom position you are now using.

A DEG in the middle clip position will be a little richer in the 0 to about 1/2 throttle position and the same as the DGH in the bottom position from about 1/2 full throttle position.  

You need to invest in a hand full of different needles so that you can make changes and learn how these carbs really work.  This is the only way you are going to learn how to tune these carbs.  There are over 125 needles that fit this carburetor.

I would recommend that you put these needles in your tuning kit.
DDE, DEF,  DEG,  DEJ, DEK,  

If one of these needles does not make your engine run correctly you probably have other problems with your basic engine package.

Excellent post! Thank you for the help!  I know I have a lot of learning to do, but i will get there!

[Jimbo45]

Update:

So I shimmed up the DGH needle with two washers, the distance of what would be a 6th notch, to richen it futher.  I bogged a lot from a rich condition, from 1/4 to 3/4 throttle, and the 162 main even seemed to rich bog a bit with this setting.

So, knowing that the DGH needle had a slight lean bog in the middle position previously, and ran good, but a bit flat at the bottom 5th position, I tried the 4th position, which I hadn't tried before.  Took it for a spin, and this seems to be the sweet spot!  It ran like a raped ape, and the needle seemed about perfect there!  Maybe the 1/8th to 3/8th throttle position seemed a touch lean, but the rest felt great!  The 162 main was a bit rich but rideable.

So, I am getting there.  If I could find a needle, that would be a touch richer in the 1/4 throttle area than the DGH, and the entire needle a notch shorter than the DGH, so I could run in the middle notch instead of the 4th notch, I think I would be dialed in!  Any needle suggestions for this situation?

Thanks for all the help guys, this is exciting, to finally get this bike ready to ride!

Got my rear Hipers that came with it installed too!

[fearlessfred]

I do not recall using a 40 but I have used a lot of 45s and 48s.  To make the engine idle correctly and not have an off idle lean hesitation when using pilots in the mid to low 40s, you may need to use a richer slide and or needle that has a smaller diameter where the needle is a constant diameter before the taper starts.  

Most guys do not want to spend the money for different slides and needles so they usually end up having to use a pilot that is in the mid to upper 50s.


Having to use a very small pilot to make the engine idle when using some popular needles like a DGH or DEJ may be a sign that your needle jet is worn and letting a lot more fuel flow between the needle and needle jet at closed throttle than a new carb would do with the same needles.

Thanks,I always like hearing your comments