Syncing Carbs

Article by Bluewing

I had some concerns with the performance of my bike; the throttle response was not right there was a lack of power and unevenness when I gave it gas. The idle was a bit rough and my gas mileage was at about 41 mpg. I decided to sync the carbs to try and solve some of this. I checked the price to get it done and it was from $100. to $150. I went with buying a manometer my self @ $120, I got Motion Pro 08-0411 mercury free, it uses propylene glycol non toxic fluid, see pick below.

 

 

After reading about the meter and the manual on how to sync the GL1200 carbs, here I go for my first carb sync.
First check and make sure your air filter is clean
Make sure you are working in a well ventilated area.
Point a fan in front of your rad to help control the heat.
Warm the bike to normal operating temperature. If you have an Aspencade remove the left and right lower faring covers. Then I calibrated my manometer, just follow the directions that come with the meter. I then removed the vacume plugs on each carb and installed the 4 adapters, one in each carb. Then I put the 4 vacume hoses on the adapters, the hose from the first tube on carb #1 and from the second tube on carb #2 and so on.

See pic below.

Start the bike and keep it at idle, do not rev the motor and let go of the throttle quickly or you could suck the liquid into your motor, this manometer does have restrictors to prevent this but I would be careful anyway. This won't harm your motor but your manometer will not work until you put replacement liquid back in it. Keep it at about 1000 rpm and look at the gauge to see how even the carbs are by the height if each row of liquid, see pic below, this is how far out my carbs were.

#4 carb does not have an adjustment; you have to sync carbs 1,2 and 3 to match carb # 4. Start with carb # 2, turn the sync adjustment screw until it matches carb # 4,

See pic below

slowly rev the motor up slightly and readjust as needed, slightly revving the motor after every adjustment. Do the same procedure on # 1 carb then # 3 carb. This can sometime take a few tries before you get it even. Using your throttle lock set your idle for 2900 rpm and fine tune the carbs as even as possible using the same procedure,

see pic below.

Once that is done shut off the bike, take the vacume lines off, remove the adapters, and install the vacume plugs, make sure not to loose the washers on the plugs and firmly install them. Replace any parts you took of the bike and you are ready to go.

I just got back from my first ride after the carbs were done; I have to say this has been a complete success. My bike has never run like this since I have had it. The throttle response is amazing; the bike has way more power and a lot smoother. This is a very noticeable difference; even the sound is more throaty and even. The Motion Pro manometer is very easy to use and I am glad I have it. I highly recommend this procedure to any of you who haven’t had it done in the last year.
 

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Ride safe have fun and enjoy. Lane