SuzukiSavage.com - Carburetor Air Screw Setting?

savagerider87 Full Member Offline Riding a quality Japanese machine since '13 Posts: 224 Northern NY Gender:	Carburetor Air Screw Setting? 04/02/13 at 04:31:34 Sorry for such a noob question, but what is the factory air screw setting on the BS 40? Which way do you turn the screw to lean the mixture out a little? My bike is running a little on the rich side. Thanks
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Dave

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Re: Carburetor Air Screw Setting?
Reply #1 - 04/02/13 at 04:39:54

I generally start at 1.5 turns when adjusting any carb. You then turn the screw in until you hear the engine start to slow down or run rough. As you turn the screw out you should hear the rpm increase and the engine start to run smooth. When you have turned the screw out far enough the engine should begin to change the exhaust tone will begin to burble which indicates the engine is running rich. You then want to turn the screw midway between those two settings (lean/rich). If you can turn the screw out 3 full turns from being lightly seated and not get a sound of running too rich - then the pilot jet is too small. (After 3 turns out the tapered screw is no longer restricting the flow and additional turns will do nothing).

Learn to use the Index in the Technical Section to do some research, there is plenty of information there that will answer most of your questions.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1181745927

Here is a list of ths stcok carb settings:
http://suzukisavage.com/cgi-bin/YaBB.pl?board=tech;action=display;num=1098869040

Here is another suggestion on how to adjust your carb:
http://suzukisavage.com/cgi-bin/YaBB.pl?board=tech;action=display;num=1157720585

Here is Serowbot's method:
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1309246277

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Coaxial Full Member Offline SuzukiSavage.com Rocks! Posts: 184 Toronto, Ontario, Canada Gender:	Re: Carburetor Air Screw Setting? Reply #2 - 04/02/13 at 05:14:00 I myself tried reading those guides still am confused. 1.5 turns clockwise ? like do we start by turning the screw clockwise all the way in or something?
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Re: Carburetor Air Screw Setting?
Reply #3 - 04/02/13 at 06:10:03

The screw has normal threads and turning it clockwise will cause it to bottom out out on the seat (do this gently). You then turn the screw counterclockwise and back the screw out 1.5 turns and start the engine. The engine should be completely warmed up before you start trying to adjust the idle mixture. Turning the screw clockwise will turn the screw in and reduce the amount of fuel, turning it counterclockwise will increase the amount of fuel in the mix.....until you get to 3 turns and then it wll not hav any additional effect.

The idle screw only has an effect on the fuel mixture at idle and at throttle settings less than about 1/8 of the full throttle movement. You may be able to help reduce backfiring by going just a tad richer.

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oldNslow

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Re: Carburetor Air Screw Setting?
Reply #4 - 04/02/13 at 06:11:15

Coaxial wrote on 04/02/13 at 05:14:00:

I myself tried reading those guides still am confused.
1.5 turns clockwise ?

like do we start by turning the screw clockwise all the way in or something?

That's correct. CAREFULLY turn the screw in(clockwise)until it stops. Don't turn it tight -just till it stops. Then turn it out 1 and one half turns.
Start the bike. Let the engine warm up, and then follow Daves directions.

Be very careful with the screw. The slot for the screwdriver isn't very deep and the screw is brass. It's real easy to bugger it up.

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bill67 Serious Thumper Offline old tired Posts: 8517 genoa city wisconsin Gender:	Re: Carburetor Air Screw Setting? Reply #5 - 04/02/13 at 06:29:57 Go back a forth till you get the highest rpm idle. from 1 1/2 open.
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Coaxial Full Member Offline SuzukiSavage.com Rocks! Posts: 184 Toronto, Ontario, Canada Gender:	Re: Carburetor Air Screw Setting? Reply #6 - 04/02/13 at 08:01:59 Thanks guys that really helps. I am immersing myself in the workings of the carburator now. I will venture into rejetting when my new muffler arrives
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Re: Carburetor Air Screw Setting?
Reply #7 - 04/02/13 at 08:10:40

Coaxial wrote on 04/02/13 at 05:14:00:

I myself tried reading those guides still am confused.
1.5 turns clockwise ?

like do we start by turning the screw clockwise all the way in or something?

Turn it clockwise like very gently until it stops. This screws it in. Then turn it out counterclockwise like 1.5 turns. Then do what Dave said.

Make sure the motor is warmed up all the way, but have a fan on it when adjusting the carb. If the motor is too cool, or if it is getting like too hot from idling a long time, the adjustment will be correct for some situation other than normal.

You'll never get it right and you'll be like OMG.

Another trick for the lazy people like me is to put it at 1.5 turns, drive it around for a few days and see how it works.
-- Then screw it out .5 turns and drive around for a few more days.
-- Then another half a turn for another few days. Etc.
-- After a while you'll find a setting where you and the bike are most happy.
-- This is not all that silly an idea because you are setting the carb for real world operations, rather than an approximate setting with the motor idling and idling and idling while you adjust it. It takes longer though.

Ain't this fun?

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Re: Carburetor Air Screw Setting?
Reply #8 - 04/02/13 at 08:25:38

Gyrobob wrote:

Quote:

Another trick for the lazy people like me is to put it at 1.5 turns, drive it around for a few days and see how it works.
-- Then screw it out .5 turns and drive around for a few more days.
-- Then another half a turn for another few days. Etc.
-- After a while you'll find a setting where you and the bike are most happy.
-- This is not all that silly an idea because you are setting the carb for real world operations, rather than an approximate setting with the motor idling and idling and idling while you adjust it. It takes longer though.

Amen to that. Plus you get to ride around a lot while yer messin' with the screw.

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Rogue_Cheddar Serious Thumper Offline Hang up the phone and drive! Posts: 725 Haverhill, Massachusetts Gender:	Re: Carburetor Air Screw Setting? Reply #9 - 04/02/13 at 08:47:57 May I also suggest to not try to adjust the screw while you're riding? I just know there are some who like to multitask.
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Re: Carburetor Air Screw Setting?
Reply #10 - 04/02/13 at 12:39:24

Rogue_Cheddar wrote on 04/02/13 at 08:47:57:

May I also suggest to not try to adjust the screw while you're riding? I just know there are some who like to multitask. Cheesy

Cool idea!! Solder a knurled knob to the screw so you can reach it and turn it easily. Wait!!! Better yet!!,... mount a rotary knob mixture control on the handlebars and a cable just like in a Cessna 150 -- turn the knob and twist the screw! Then you can futz around with the mixture as easily as flicking on the high beam. Of course, it'll only make much diff at idle, but what a conversation starter, eh?

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« Last Edit: 04/02/13 at 14:42:34 by Gyrobob »

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Re: Carburetor Air Screw Setting?
Reply #11 - 04/02/13 at 13:21:24

There are some companies that sells screws that don't require a screwdriver and they make them for installation in common motorcycles - so you can adjust the mixture screw. I had a Kawasaki Super Sherpa that once you removed the brass anti-tamper knob - the mixture screw was still not accessible unless the carb was off the bike. The screw was on the bottom of the carb and there was no room between the engine case and mixure screw to get anthing in there to reach the screw.....but you could reach an extended knob.

http://www.koubalink.com/fuelscrew.html

With our carbs there isn't any reason you could not solder on an extension for your fingers.

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: Carburetor Air Screw Setting? Reply #12 - 04/03/13 at 10:54:42 Step one Small screwdriver, fingertips only, close the needle & count the turns. That way, you can always put it back where it was. The tip is soft. Close it softly. Tighten it? NO.
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Re: Carburetor Air Screw Setting?
Reply #13 - 04/04/13 at 17:49:56

justin_o_guy2 wrote on 04/03/13 at 10:54:42:

Step one
Small screwdriver, fingertips only, close the needle & count the turns.
That way, you can always put it back where it was. The tip is soft. Close it softly. Tighten it? NO.

JOG did you ever write for Penthouse Forum? Cheesy

(sorry I'm sleep deprived the boy had me up very early today........slinks away to bed)

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