air adjustment screw
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Senior Member
SuperSport
Joined: Jul 2012
Posts: 582
From: Santa Fe, New Mexico
air adjustment screw
I've had several bikes with duel carburation and they have all had air mixture screws for each carburetor. The general rule of thumb is 2 to 2 1/2 turns out and tune the second carb to that. Why does the hawk fix the front carb with no way to adjust? The only way to adjust, (that I can tell), is to adjust to the front carburetor. So, if I want to adjust the bike to run a bit rich because I put new cans on all I can do is adjust the rear? That doesn't make any sense! I read here all the time how some have adjusted to running 1 1/2 turns, or 2 and so forth. What am I missing?
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Superstock
Superstock
Joined: Jun 2005
Posts: 489
From: San Antonio, TX
You may be identifying the throttle synchronization screw mistakenly as an idle fuel mixture adjustment screw.
US models have one 'D' shaped mixture screw on each carb pointing downward just outside the float bowl.
US models have one 'D' shaped mixture screw on each carb pointing downward just outside the float bowl.
Thread Starter
Senior Member
SuperSport
Joined: Jul 2012
Posts: 582
From: Santa Fe, New Mexico
I did mean pilot screw. So the single screw on the rear carb is for balancing only? The pilot/fuel mixture can be set on each carbuerator? In the past I have done this by ear, set one cylinder as perscribed by the manuel and then setting the second by ear and then working the two to get the best balance depending on how ritch or lean I want to go. Same on the hawk?
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MotoGP
Joined: Nov 2006
Posts: 6,109
From: Skurup, Sweden
oops, I did mean pilot screw. So the single screw on the rear carb is for balancing only? The pilot/fuel mixture can be set on each carbuerator? In the past I have done this by ear, set one cylinder as perscribed by the manuel and then setting the second by ear and then working the two to get the best balance depending on how ritch or lean I want to go. Same on the hawk?
I did mean pilot screw. So the single screw on the rear carb is for balancing only? The pilot/fuel mixture can be set on each carbuerator? In the past I have done this by ear, set one cylinder as perscribed by the manuel and then setting the second by ear and then working the two to get the best balance depending on how ritch or lean I want to go. Same on the hawk?
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Senior Member
SuperSport
Joined: Jul 2012
Posts: 582
From: Santa Fe, New Mexico
since this bike has never been synced, or had any service done to that part of the bike as far as I know of, I am in process of getting that little boost joint for the front carburetor and setting things up for easy sync in the future. I believe the bike is running a tad lean with the addition of the two bros cans so a tweak to the rich side is in order. I think this bike could run better and I think a simple tune up will go a long way to making it run the way a bike like this should run. PO did nothing but change the oil. Off topic: the mobil 1 motorcycle oil has made a slight difference in the way it shifts, for the better!
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MotoGP
Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
since this bike has never been synced, or had any service done to that part of the bike as far as I know of, I am in process of getting that little boost joint for the front carburetor and setting things up for easy sync in the future. I believe the bike is running a tad lean with the addition of the two bros cans so a tweak to the rich side is in order. I think this bike could run better and I think a simple tune up will go a long way to making it run the way a bike like this should run. PO did nothing but change the oil. Off topic: the mobil 1 motorcycle oil has made a slight difference in the way it shifts, for the better!
So to start, I would slowly turn the screws in until they seat lightly while counting the number of turns.
Write this information down and don't be surprised if the rear is open more than the front.
Then open the screws 1\2 turn more than stock. Then write those numbers down.
Now you have a base line and can tweak from there.
Sorry if you already know all this, just trying to give a complete answer.
Also I do believe the bike runs well with 1 size larger pilot jets but that is covered in the carb thread.
Thread Starter
Senior Member
SuperSport
Joined: Jul 2012
Posts: 582
From: Santa Fe, New Mexico
The bottom end is lean from the factory for emissions reasons.
So to start, I would slowly turn the screws in until they seat lightly while counting the number of turns.
Write this information down and don't be surprised if the rear is open more than the front.
Then open the screws 1\2 turn more than stock. Then write those numbers down.
Now you have a base line and can tweak from there.
Sorry if you already know all this, just trying to give a complete answer.
Also I do believe the bike runs well with 1 size larger pilot jets but that is covered in the carb thread.
So to start, I would slowly turn the screws in until they seat lightly while counting the number of turns.
Write this information down and don't be surprised if the rear is open more than the front.
Then open the screws 1\2 turn more than stock. Then write those numbers down.
Now you have a base line and can tweak from there.
Sorry if you already know all this, just trying to give a complete answer.
Also I do believe the bike runs well with 1 size larger pilot jets but that is covered in the carb thread.
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