Hypercharger Mods for the 800 Vulcan

For some time, many 800 owners have been plagued by the quirks exhibited by the Kuryakyn Hypercharger. While an easy conversion for the 1500 Vulcans, the Hypercharger installation on the 800 Vulcan has often proven to be much more temperamental. Many have experienced much difficulty in rejetting, problems caused by riding in strong headwinds, stumbling at part throttle, etc.

After a bit of experimentation it became obvious that the carb venturi pressure was rising substantially above that of the carb bowl. The CVK carbs used on the Vulcans requires the opening of the emulsion tube in the venturi to be at a lower pressure than that of the bowl. When the pressure rises above that of the bowl, fuel flow stops. Many sport bikes, with ram air intakes, pressurize the carb bowls at a higher level than that of the venturi to insure adequate fuel flow at all speeds. After a bit of experimentation, pressurization of the carb has proven to be an easy task, and really tames the Hypercharger into an easily tuned intake system.

Pressure measurements at hiway speeds were measured at various locations within the Hypercharger with a manometer. The common connection of the manometer was piped under the tank, into a "quiet" location, while the "high" side connection on the manometer was attached inside of the Hypercharger with double sided tape. The highest pressures were measured at the point indicated in the photo above. At this point, a hole was drilled into the rear of the Hypercharger, tapped to 1/8 NPT, and a hose barb fitted. This hole was drilled through a casting mark, seen from inside of the Hypercharger at the point indicated in the photo above. Then, on the inside of the Hypercharger, I used a dremel tool to remove any of the hose fitting that protruded into the Hypercharger area, so it is a "flush" connection as viewed from inside.

This is a photo of the back side of the Hypercharger, showing the hose connection installed to supply pressure to the carb. Notice the spacer that bolts between the Hypercharger and the chrome mounting bracket. Yours won't have that black allen screw (seen here just below the black hose), as that's a plug that was installed to fill an 'experimental' port. Hey, you gotta experiment if you want to know for sure :-)

Here's a shot of Pusher holding the modified Hypercharger. The pressure from the Hypercharger is routed through a small filter (cheapie $2 fuel filter) to keep small critters and other contamination from being blown into the carb bowl.

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