Yes, it was. The factory set the screws using emission testing equipment, then put caps on them. But as stated earlier, they were typically set lean to produce a lower emission reading. They were also set at sea level. But slight adjustments are needed to compensate for many factors such as altitude, jetting for aftermarket pipes, pod filters, etc. And last I checked, the EPA doesn't do any surprise inspections on old Suzukis, and I'm not aware of any of the 50 states requiring smog tests on these old bikes.
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The question has already been answered, I will just offer confirmation on each of your questions.
You have no "air screws".
You DO have "idle mixture adjustment screws" as Chef said.
Note that all adjustment screws operate the same way. When you turn them IN, they reduce whatever they are controlling.
When you turn them OUT, they increase it. The trick is to know what they are controlling.*
In your case, you have CV-style carbs. That is the only external adjustment, and, as Chef said, it controls a pre-set mixture, so the answer to your question is "both". It adds more fuel to the air flow at idle speeds, so yes, it does richen the mixture when you turn it OUT. By the way, a good starting point is three full turns out from lightly seated. When the engine is warmed up, turn each screw slowly, listening for highest engine rpm. Lower the master idle speed, if necessary, repeat for each mixture screw.
*On the VM carbs, the pilot fuel screw (the one on the bottom) controls fuel, so turning it OUT will add fuel, richening the mixture.
The pilot air screw (the one on the side) controls air, so turning it OUT will add air, leaning the mixture.
Whose "future help"? I don't know of anyone on this board that does not recommend adjusting for proper combustion.
We ALL agree that it was not proper from the factory and offer suggestions on how to set it.
And that is not even considering the fact that you have to remove it completely to properly clean the carbs and change the o-ring.
Now, an appeal: we have several on this board that are currently, or have been in the past, mechanics at a dealership. When is the last time you saw anyone from the EPA visit your shop, let alone impose a fine on an "improperly" tuned bike? Has anyone ever heard of the EPA making a visit at an owner's house to do an inspection or impose a fine?
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mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
#1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
#2 son: 1980 GS1000G
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Oh, the guy left behind for example...gsxr.
Also, I'm not "infected" with your laws. My Clymer manual saze so...'bout EPA.
Also, I have NEVER troubled these screws, well only on a 1979 425 (NOT blanked).
I have also NEVER soaked my carbs., always ONLY removed sump and "top" and "spray" cleaned. Even with a tank full of rust after sitting outside over a decade. Well, maybe UNNECESSARILY the choke assy.
The point is, my opinion, these screws are being modified over some other cause.
I also have no need to open my carbs. after bike is going once I DRAIN sumps MONTHLY.
Maybe, instead of rushing people to their air-screws, suggest instead to try the fuel octane that is suggested in the owners manual.
Note, also, I have never the need to ask any questions or help, personally.Last edited by Guest; 03-23-2010, 01:15 AM.Comment
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