Carburetion/Fuel

From Suzuki RV Wiki

The RV90 uses a Mikuni VM17 carburetor. The VM17 is a roundslide, spigot mount carb, and a member of the venerable Mikuni VM family of carbs. The carburetor mounts on a spigot that comes out of the right side of the engine case. The carb does not mount directly to the cylinder like many engines, instead, it is mounted inside the case underneath a cover, and intakes directly into the crankcase.

The carb area inside the right case has two ports molded into the bottom of the case, underneath the carb, see the image to the right.

The round port on the left is a drain port that will take carb overflow and route it out the bottom of the case. The oval port on the right is a case drain port that will drain any gas that runs out of the carb body itself. The carb drain port on the left needs to have the drain hose running from the carb to it, as pictured. The right hand drain port needs to have a piece of filter foam stuffed in it, which is not pictured in the image to the right. If both of these things (drain hose and foam) are not in place, the carb will intake unfiltered air through the case drain. It will also run lean.

The manual doesnt mention these things, nor does any of the parts fiche online include the foam for the case. However, both ports need to have their respective hose and foam in place, or the bike wont run quite right, and will be hard to tune.