Linking the Vacuum Ports

This is a simple and near zero cost modification that improves low end throttle response and is claimed to increase gas mileage. (yet to be verified) The only drawback is that it causes a slightly irregular idle.

Step 1 - Remove the rubber plugs from the vacuum ports of cylinders 2 and 4 and the AIS hoses from cylinders 1 and 3.
Step 2 - If you have already disabled the AIS by plugging the hoses going to the exhaust ports, then the small rubber hoses attached to the vacuum ports of cylinders 1 and 3 can be left disconnected. For protection, they should be plugged. (a spent .22 shell fits very nicely)
Step 3 - If you plugged the hoses in step 2, then connect a piece of 3/16" fuel line between the vacuum ports of cylinders 1 and 2. Connect another piece of line between cylinders 3 and 4. Skip to step 5.
Step 4 - To leave the AIS vacuum control enabled, connect the control hose to a small T fitting with the other 2 ports of the fitting to the vacuum ports of cylinders 1 and 2. Repeat for the other side. (A suitably sized brass T is available from aquarium supply stores.)
Step 5 - Ride your bike and enjoy the increased performance and mileage!

Last update: 04:57 PM Sunday, September 26, 2004

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