top end power loss???
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Intermediate
Joined: Sep 2012
Posts: 30
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From: california
The main jet is a 190, picked a 180, and 185 today,Will change that out and see what happens. The pilot jet is a 45. Makes sence it would be to rich if that's what u got with drag pipes!! Do u think there will be a need to adj the mixture screw at all???
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Joined: Apr 2012
Posts: 2,938
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From: North Florida
Ok some basic 101 carb tuning.
First you never change more than one thing at a time.
You always start with the idle jet, this jet flows all the time, so it affect all the other jets when it is changed.
Make sure the idle adjustment screw is drilled out and opened up.
Put in a jet larger than you think you will need then start leaning it out with the idle screw.
if you cant get lean symptoms then the jet is to large.
When you start getting lean symptoms, then screw the screw out half a turn.
Then turn the screw gently all the way in counting the turns, if it is more than three and a half then the jet is to large go to the next smaller jet.
You should be about two turns out.
Lean symptoms are a cough or hesitation when you slightly try to accelerate.
Also when you start the bike, you should need the choke, (enricher) only on cold starts.
If you have to choke hot then the bike is too lean.
If you dont have to choke cold the bike idle is too rich.
The idle screw is the best way to tell if you are to lean or rich a jet.
The midrange is controlled by the needle. I am not familiar with the needle you are talking about but assume it is the 87 sportster, or is it 88 that did not have a accelerator pump.
This needle is thinner than the stock needle.
It is much richer, and makes the main jet kick in faster.
People use this needle so they dont have to change the idle jet.
So you should not use this if you are changing the idle jet unless you are taking the effect into consideration.
In all honesty usually you dont have to worry about changing the stock needle jet in most cases.
Some people will shim the stock needle up so it will kick the main in sooner, giving the mid extra gas.
After you get low and mid then you worry about the high speed jet, you tune it the same as the low speed, except you do not have a high speed adjustment.
Start out rich then lean it out by going to a smaller jet to see how it runs.
Lean symptoms are a cough, (because the gas is to lean to ignite) rich symptoms are sluggish performance.
You can check the plugs with a plug chop. Wide open throttle cut the motor and pull the clutch and roll to a stop, pull the plug.
But personally I do a seat of the paints, change jets going smaller until it runs best without symptoms.
Also keep an eye on gas mileage, this is a good indicator of how rich you are, good gas milage, = lean, bad, = rich.
First you never change more than one thing at a time.
You always start with the idle jet, this jet flows all the time, so it affect all the other jets when it is changed.
Make sure the idle adjustment screw is drilled out and opened up.
Put in a jet larger than you think you will need then start leaning it out with the idle screw.
if you cant get lean symptoms then the jet is to large.
When you start getting lean symptoms, then screw the screw out half a turn.
Then turn the screw gently all the way in counting the turns, if it is more than three and a half then the jet is to large go to the next smaller jet.
You should be about two turns out.
Lean symptoms are a cough or hesitation when you slightly try to accelerate.
Also when you start the bike, you should need the choke, (enricher) only on cold starts.
If you have to choke hot then the bike is too lean.
If you dont have to choke cold the bike idle is too rich.
The idle screw is the best way to tell if you are to lean or rich a jet.
The midrange is controlled by the needle. I am not familiar with the needle you are talking about but assume it is the 87 sportster, or is it 88 that did not have a accelerator pump.
This needle is thinner than the stock needle.
It is much richer, and makes the main jet kick in faster.
People use this needle so they dont have to change the idle jet.
So you should not use this if you are changing the idle jet unless you are taking the effect into consideration.
In all honesty usually you dont have to worry about changing the stock needle jet in most cases.
Some people will shim the stock needle up so it will kick the main in sooner, giving the mid extra gas.
After you get low and mid then you worry about the high speed jet, you tune it the same as the low speed, except you do not have a high speed adjustment.
Start out rich then lean it out by going to a smaller jet to see how it runs.
Lean symptoms are a cough, (because the gas is to lean to ignite) rich symptoms are sluggish performance.
You can check the plugs with a plug chop. Wide open throttle cut the motor and pull the clutch and roll to a stop, pull the plug.
But personally I do a seat of the paints, change jets going smaller until it runs best without symptoms.
Also keep an eye on gas mileage, this is a good indicator of how rich you are, good gas milage, = lean, bad, = rich.
Outstanding HDF Member
Joined: Apr 2012
Posts: 2,938
Likes: 30
From: North Florida
Now that you are going to a more restrictive pipe, the carb is to rich. Plus the bigger main and the richer needle will make the bike very sluggish at higher rpms.
Yes you need to adjust the idle jet, read the above post.
In all honesty I would start out with the stock jets, and put in the stock needle then go from there.
Outstanding HDF Member
Joined: Apr 2012
Posts: 2,938
Likes: 30
From: North Florida
Yep did a search for cv performance needle and got this.
Product Description
A direct replacement for the factory discontinued Harley N65C needle. The classic N65C needle was originally fitted to the first CV carburetor on 1988 Harley-Davidson Sportsters that lacked an accelerator pump, therefore requiring a needle with a richer profile to overcome the lean stumble. For years tuners and techs have used the N65C needle to custom tune all model Harley CV carburetors to deliver the optimal amount of fuel just off idle and to smooth acceleration. Replaces p/n 27094-88.
CV Performance has brought the Harley N65C needle back using the original factory profile spec while utilizing our own machining process not found anywhere else. CNC milled from aircraft quality billet aluminum for precision and durability. Will fit all Harley constant velocity (CV) carburetors on 1989-2006 Big Twin and Sportster models.
if you are going to use this then you need a even leaner idle jet, so use the stock needle.
Product Description
A direct replacement for the factory discontinued Harley N65C needle. The classic N65C needle was originally fitted to the first CV carburetor on 1988 Harley-Davidson Sportsters that lacked an accelerator pump, therefore requiring a needle with a richer profile to overcome the lean stumble. For years tuners and techs have used the N65C needle to custom tune all model Harley CV carburetors to deliver the optimal amount of fuel just off idle and to smooth acceleration. Replaces p/n 27094-88.
CV Performance has brought the Harley N65C needle back using the original factory profile spec while utilizing our own machining process not found anywhere else. CNC milled from aircraft quality billet aluminum for precision and durability. Will fit all Harley constant velocity (CV) carburetors on 1989-2006 Big Twin and Sportster models.
if you are going to use this then you need a even leaner idle jet, so use the stock needle.
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