A common question that many people have is -why do jet ski carburetors need to be rebuilt?- Winter storage and ethanol are the two major drivers. Failing to put in a gas stabilizer (and making sure it gets into the carburetors while you're flushing to prep for storage) can cause water and/or moisture to get into the gas. If any water or moisture is in the gas and it sits in a carburetor all winter, there will probably be issues. And the ethanol in gas eats away at rubber and plastic parts, limiting their lifespan. SBT recommends rebuilding your jet ski carburetors every 2 years.
If you have any questions about rebuilding your carburetors, SBT's tech support department is ready and willing to help answer your Jet Ski part questions.
SBT sells Mikuni and Keihin rebuild kits. For Mikuni, SBT has kits for the BN, SBN, and SBN-I carburetors. The BN carburetor will have a round 6 bolt pattern above the diaphragm, whereas the SBN carburetor will have a square 4 bolt pattern. For Keihin, SBT has kits for the CDK and CDK-II carburetors. Your diagram will be helpful when putting it all back together.
When you are working on a personal watercraft, you can save money by rebuilding the carburetor yourself!