Carb Jetting Instructions
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Transcript of Carb Jetting Instructions
7/17/2002 Sherco Carb Jetting 1
Sherco Carb Jetting Instructions
This manual provides instructions on how to remove and reinstall the stock carburetor, it also shows you how to change the pilot jet and the main jet. It is intended to be used for all Sherco 1.25 2.9 Trials Motorcycles.
The motorcycle shown is a new 2002, 2.9, the one that you are working on may be slightly different but the principles shown will apply to all of the models indicated.
The technician shown in the photographs is David Chaves who received his training at the Sherco factory in Spain. David is also a member of Team Sherco and is competing in the NATC national series as a Champ rider.
If you have any question or are not certain about any procedure call Ryan Young Products on 1-800-607-8742.
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The First Step is to Remove the Rear Fender.
Remove the 2 rear fender mounting bolts.
Remove the front mounting bolt.
Disconnect the taillight harness.
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The Second Step is to Remove the Fuel Tank
Remove the top fuel tank mounting bolt and disconnect the fuel overflow line and the fuel line.
Remove the airbox by removing the 3 mounting screws.
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Air Box Removal Continued
Notice that David is loosening the rear clamp, the one that attaches the air box to the rubber manifold.
Do not loosen the clamp that attaches the rubber manifold to the carburetor.
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To facilitate the removal of the air box remove the fender retaining nut.
Remove the air box and set it aside.
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Loosen the 2 screws that retain the carb slide, remove it and set it aside.
David hangs it over the side of the frame as shown.
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Loosen the manifold clamp at the carburetor.
Remove the carburetor from the frame as shown.
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Changing the Jets
Set the carburetor on a clean surface.
Use a 14 mm wrench and remove the main jet holder.
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Main jet holder
Set the float bowl upright as shown in order to keep the floats from falling out of the bowl.
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To change the main jet hold it in a 14 mm box end wrench and use a straight screw driver that fits it tight, remove it and replace it with the appropriate one for your operating conditions.
The pilot jet is located in the body of the carburetor as shown, to change it use a straight screw driver that fits it tight, remove it and replace it with the appropriate one for your conditions.
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Replacing the Float Bowl
Notice how David holds the carburetor body and the float bowl, this method insures that the floats do not fall out of the bowl.
Install and tighten the main jet holder.
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The jets are changed and the carburetor is ready to be reinstalled.
For the most part the assembly process is just the disassembly reversed.
We will make note of a few things that David does to make the job go smoother.
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Carburetor Installation Tips
David routes the fuel line under the engine breather line as shown.
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Install the carb as shown.
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Reinstall the slide, look to make sure that it is installed properly.
David operates the throttle and makes sure that the slide is operating properly.
This is CRITICAL, take your time and do this right.
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David installs the air box and the fuel tank before he tightens the carburetor clamps. He does this so that he can rotate the carburetor in order to provide operating clearance for the choke lever.
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Rotate the carburetor so that the choke lever operates properly. Now tighten the manifold clamps.
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External Carburetor Adjustments
There are 2 screws that allow you to make adjustments to the carburetor, the one on the right is the idle adjustment screw and the one on the left is the GAS screw.
Turning the idle screw in (clockwise), increases the idle speed, turning it out decreases the idle speed.
Turning the GAS screw out (counter clockwise) makes the idle mixture richer and turning it in makes it leaner.
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Tighten all the bolts, connect the fuel lines, install the rear fender and the bike is ready to be test ridden.
If you have any questions or are not certain about any procedure call Ryan Young Products on 1-800-607-8742.