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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Pilot Air Adjusting Srew /cgi-bin/YaBB.pl?num=1174429328 Message started by georgekathe on 03/20/07 at 15:22:08 |
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Title: Pilot Air Adjusting Srew Post by georgekathe on 03/20/07 at 15:22:08 I'm curious - which way richens the mix - screwing the screw clockwise or counterclockwise? when I screwed it counterclockwise was when I got rid of 90+% of my "banging." |
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Title: Re: Pilot Air Adjusting Srew Post by serowbot on 03/20/07 at 15:35:00 clockwise or in, is leaner. |
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Title: Re: Pilot Air Adjusting Srew Post by Greg_650 on 03/20/07 at 16:03:48 As I understand it, this is an "Air Adjusting Screw" therefore if you turn it in you decrease the air to fuel ratio which makes it richer. If you turn it out the air to fuel is increased which makes it leaner. Finding the "happy place" in the middle of those extremes is where you want to be. Under the diaphragm cover on top is where you'll find the fixed pilot fuel jet. Lancer, old Buddy, "What say you?" :P |
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Title: Re: Pilot Air Adjusting Srew Post by georgekathe on 03/20/07 at 18:11:12 darn - I knew I'd get conflicting opinions, but not in the first 2 responses! :) (I wanted to address this to Lancer but thought I'd be polite & throw it open to all) :) so, to echo Greg - over to you, Lancer... ;D (incidently, I am refering to the screw on the side of the carb - formerly covered by the brass plug - hope I got my terminology correct). |
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Title: Re: Pilot Air Adjusting Srew Post by serowbot on 03/20/07 at 18:54:59 I'm working on the theory that you turn out/cc to correct the factory lean backfire, and if you must go more than 3 turns out you need a bigger pilot jet. I believe you are actually increasing and decreasing the diameter of a small fuel passage coming up from the float bowl that exits just on the intake side of the throttle valve. Now..., watch me be wrong on this... Lancer? |
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Title: Re: Pilot Air Adjusting Srew Post by LANCER on 03/20/07 at 19:46:22 Carburetors can have two different types of air or fuel mixture screws. This one seems to be called the pilot air adjusting screw, even though it is technically a fuel mixture screw. The air mix screw is located on the filter side of the carb, while the fuel mix screw is located on the engine side of the carb. The adjustments on these types run opposite of each other. The one on the Savage carb is on the engine side and is therefore actually a fuel mixture screw. For this one, turning CC will richen the mixture. Got to go for now. |
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Title: Re: Pilot Air Adjusting Srew Post by georgekathe on 03/20/07 at 21:31:26 sorry Lancer - maybe it is me being thick - I'm refering to the screw on the side of the enigne nearest to your right leg - the one that people can only get at after drilling out the brass plug. I turned it counter clockwise & got rid of virtually all my backfire. was I richening or leaning out the bike? thanks for first reply - sorry if I'm sounding confused - would appreciate clarification, Lancer. :) |
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Title: Re: Pilot Air Adjusting Srew Post by Greg_650 on 03/20/07 at 21:46:47 LANCER wrote:
Oh no...No fair. You aren't skating out that easy....you can adjust fuel "mixture" by changing the air too. The fixed pilot air jet (fuel) is located in the top. It is factory fixed. You can't remove it (cause the slots are gone). The screw we're talking about that normally has a plug, adjusts the air flow. Sure it runs opposite, which is what I said. Turning in closes it down and cuts the air and makes it richer. Out is leaner. Either way, on the opposite extremes the bike runs rough. So you adjust for the sweet middle spot. Lets not confuse this with the pilot jet shown below, which everyone changes. http://i21.photobucket.com/albums/b277/gmdinusa/MikuniJets_1823.jpg Of course, the important thing to know...you too George :P Adjust it until you find the middle point when the bike runs smooth and then forget it. |
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Title: Re: Pilot Air Adjusting Srew Post by georgekathe on 03/20/07 at 23:00:11 from what you said Greg guess my turning it out made bike run leaner, which I thought would not make bike lose popping. however, as it turned out it did. whatever, end result was :) |
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Title: Re: Pilot Air Adjusting Srew Post by Rockin_John on 03/20/07 at 23:19:33 georgekathe wrote:
Greg is wrong. The idle mix screw in question is regulating fuel, just as it does in about every carb design. There are rare carbs that have a seperatly adjustable idle air regulation, but they are the exception. That is, unless you want to consider the idle speed adjust screw to be an "air" screw, which would be wrong by most conventional thinking. In this case: CCW = rich and CW = lean As for the "sweet spot in the middle" you aren't going to find it sitting in your driveway... The best way is to Road Test: screwdriver at the ready. :) |
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Title: Re: Pilot Air Adjusting Srew Post by LANCER on 03/21/07 at 05:14:47 We have what is called a variable venturi type of carburetor. It has a slide (throttle valve) that goes up and down, and does it either mechanically like in a VM carb or by using engine vacuum like in the stock CV carb. In this type of carburetor there can be two types of idle mixture control, or even both types, on the carburetor depending on what the manufacturer wants to do. Air Mixture Screw On a mechanical slide carburetor, the air mixture screw is always located on the air filter side of the carburetor slide. It varies the flow rate of the air bleed passageway. To create a richer air/fuel mixture, you turn the air mixture screw in (clockwise). This reduces the amount of air allowed to enter the ciruit, creating a rich mixture. To create a leaner air/fuel mixture, you turn the air mixture screw out (counter clockwise). This increases the amount of air allowed into the circuit, causing a leaner mixture. Fuel Mixture Screw This screw is always located on the engine side of the carburetor slide. The fuel mixture screw controls the amount of the fuel exiting the idle outlet port. The fuel mixture screw changes the amount of fuel entering the carburetor while the engine is at idle. When this screw is turned out (counter clockwise), it enriches the air/fuel mixture by increasing the amount of fuel allowed to enter the circuit. When the fuel mixture is turned in (clockwise), the mixture becomes lean by reducing the amount of fuel allowed to enter the circuit. When a fuel mixture scew is used on a street motorcycle, the carburetors have factory-installed anti-tamper plugs over the screw to prevent the untrained consumer (this is a secret code, meaning US) from changing the factory and EPA approved setting. The stock Savage/S40 carb has the second type, the fuel mixture screw, though it is referred to as the pilot screw in the Parts Manusal (microfich) and Clymer does not address it at all. The Suzuki Service Manual does not mention it all either. I have usually used the term pilot air adjusting screw in the past, and if that has confused anyone I apologize. I just got in the habit of doing that. A lot of instructions from assorted sources use the same term, but for the stock carb on our engine it is more correct to call it a fuel mixture screw. On the Mikuni VM carburetors the screw is of the first type, it is an [i][b]air mixture screw, or may be called the pilot air screw[/b][/i]. On this carb turning the pilot air adjusting screw IN (clockwise) will richin the mixture, and OUT (counter clockwise) will lean the mixture. I hope this is helpful and that I have not confused anyone. Also, I have a nagging feeling that I may have given incorrect info to a few in the past regarding the direction of the pilot air screw adjustment on the VM carburetor. If so, then I humbly apologize for that. There have been occasions when I was getting questions on several types of carbs at the same time and I could have mixed the info from one to the other. If it did ...I am sorry. Anyway, the information above is directly from a training manual. I did not want to try to condense the instructions this time, so I wrote it out as it is printed. That helps to eliminate problems. |
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Title: Re: Pilot Air Adjusting Srew Post by Savage_Rob on 03/21/07 at 05:22:46 Rockin_John wrote:
That is correct. I think the confusion is in how everyone refers to this screw at different times. I prefer to call it the pilot adjustment screw so that it pairs in one's mind with the pilot jet since they are both parts of the same fuel circuit. Some folks call it the fuel/air mixture screw. That is partially correct in that it alters the fuel to air ratio in the pilot circuit. The problem is that it's not the only adjustment screw on the carb that fits that description; it's just the one for the pilot circuit. Even worse is when the name is shortened to pilot air adjustment since the screw actually adjusts fuel. I also hate to use the word "idle" in this case because it is then sometimes confused with the "idle speed screw". But then I still occasionally use the term "choke" when it's actually an "enrichener" on this carb (and on my Amal too) because it adds fuel instead of throttling air. Some carbs have true chokes which reduce the air instead. Just an old habit I try to correct whenever I realize I'm doing it. |
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Title: Re: Pilot Air Adjusting Srew Post by Five_Points on 03/21/07 at 07:25:03 hey georgekathe, the screw you are referring to on the right side, that was formerly covered by the brass cap: Counter Clockwise to richen Clockwise to lean out |
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Title: Re: Pilot Air Adjusting Srew Post by klx650sm2002 on 03/21/07 at 08:31:04 The FCR 41 on KLX has both an air mixture screw and a fuel mixture screw. She also has 7 positions of adjustment on the needle, to which I've just (today) added a washer to get 4.5 clicks from the top (just as a try-out). Clive W :D |
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Title: Re: Pilot Air Adjusting Srew Post by Greg_650 on 03/21/07 at 08:39:40 Rockin_John wrote:
Still exhibiting your extensive array of people skills and other true lies, I see. |
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Title: Re: Pilot Air Adjusting Srew Post by georgekathe on 03/21/07 at 08:53:35 agghh! my head hurts! ;D think I'll just sign off on this thread now & leave well enough alone - the screw I turned counter clokcwise on the right side (ie where your right leg is) that used to be covered over by the brass plug got rid of the popping. think I'll leave it at that - whether it richens or leans out the bike it had the desired effect. over & out :) |
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Title: Re: Pilot Air Adjusting Srew Post by Rockin_John on 03/21/07 at 09:07:00 Greg_650 wrote:
I said it like that just for you. ;) You didn't disappoint me! ;D |
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Title: Re: Pilot Air Adjusting Srew Post by Greg_650 on 03/21/07 at 09:07:13 LANCER wrote:
Well, actually, your word usage isn't wrong as the SSM calls the screw a Pilot Air Screw and a Pilot Screw, depending on the particular Spec sheet you are reading. Just a bit of confusion that I guess comes from changes over 2 decades. In the earlier models, or on a few foreign models some jets exist that aren't even present now. However, I guess that I was wrong and had the actual operation backwards. I didn't realize the "filter vs. engine side" differentiation. I appreciate your explanation. It's certainly more intelligent, anyway. Still though, the adjustment instructions that I have read and used, do not concern "rich or lean" they only concern finding the smoothest running position located mid point between "in and out". On ours, the adjustment was simple and hasn't been touched in a couple years. We don't ride around with screwdrivers like some kind of newbie. |
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Title: Re: Pilot Air Adjusting Srew Post by Greg_650 on 03/21/07 at 09:09:10 Rockin_John wrote:
Always the mental midget. |
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Title: Re: Pilot Air Adjusting Srew Post by Greg_650 on 03/21/07 at 09:14:31 georgekathe wrote:
Well, as Lancer pointed out, I had the operation reversed. However the adjustment is the same. No need to try to adjust it for either lean or rich. Once you get it set, you could put the plug back if you wanted... |
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Title: Re: Pilot Air Adjusting Srew Post by verslagen1 on 03/21/07 at 09:14:34 That's rich! ;D |
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Title: Re: Pilot Air Adjusting Srew Post by Greg_650 on 03/21/07 at 09:23:06 Savage_Rob wrote:
Yep. Different subject but similar confusion. The knob for this function says "Choke" whereas, if you're looking at the carb schematic the word is replaced with "Enrichment". Instead of closing off the air, it opens up more fuel...different means to the same end. |
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Title: Re: Pilot Air Adjusting Srew Post by Rockin_John on 03/21/07 at 09:27:27 georgekathe wrote:
Wait George!!! There's still so much to worry about: It is against Federal law for individuals as well as pro mechanics to tinker with that screw. The civil penalty for an individual is up to $2500 per occurrence! A dealer or shop can be fined $25K per !!! OUCH !!! :o http://www.epa.gov/compliance/resources/policies/civil/caa/mobile/engswitch.pdf Shhh.... |
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Title: Re: Pilot Air Adjusting Srew Post by Rockin_John on 03/21/07 at 10:06:10 Greg_650 wrote:
Let's see... You sink into personal attack mode; in two posts or less; if I dare to differ with you, but I'M a "mental midget" and in need of "people skills." Maybe that all adds up in your world. You need to get over me and move on honey. :-* ;) ;D Bet it's not the first time you've been told that! |
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