QuestionI recently bought a 1979 CB750K that had been in storage about 20 years. I cleaned it up, put new fluids in it and it started right up but the drain hoses on the bowl floats run gas. Is this hard to fix and what is involved?
AnswerIF the carbs were left with 20 year old gas in the float bowls, then it is amazing that it started at all. Evaporated gas will leave varnish deposits, gummy goo and all kinds of unpleasant things in there. The entire fuel system needs to be checked for debris, rust, varnish, etc.
That includes the fuel tank, petcock (fuel valve), fuel lines and carbs.
To do it properly, you have to disconnect the carb rack, fully disassemble all four carbs, boil out the parts in carb cleaner, buy at least 4 new rebuild gasket kits, then reassemble it all, reinstall and synchronize the carbs and you are on your way.....
Options: Go to your Yamaha dealer and find some Yamaha carb cleaner solution, mix with gasoline as instructed and then let it sit overnight, drain carbs, refill the fuel system with fresh fuel and pray that you get lucky enough to prevent the above procedure.
If you have a small tipped phillips screwdriver with a long shank, but short handle, you might be able to remove the float bowls and clean things with carbs in place. Somewhat of an advanced procedure, though, if you don't have tools and a good workplace to do this, plus some expertise in repairing carbs.
After 20 years, fork seals, hydraulic brake systems, drive chains, tires and cables will all need attention before you go out tearing around the town. If you can't do this work, have someone with experience check it over for you.
Shop manuals are available from www.helminc.com, www.motorcyclebooks.com or www.motorcyclememories.com
Bill Silver
