QuestionWhen I'm riding my 1975 honda cb200t I have the petcock turned to the
"on" position. Randomly it will act like its out of gas and turn off. The
only way I can start it again is if I switch the petcock to "reserve". Then it
starts fine and gets me home. I just had this bike serviced at a Honda
dealer and they found sediment in the tank. They cleaned the tank out
and put inline fuel filters on. Also, later I can start the bike up in the "on"
position and ride it till it acts up again. Is the petcock switch bad?
AnswerIssac.... here is the petcock in exploded view:
http://www.cmsnl.com/honda-cb200t-usa-1976_model425/partslist/F++11.html
If the tank was rusted/contaminated inside, I would hope that they completely cleaned the tank AND the petcock, by disassembling it to clean out the cross drilled passageways inside. Replacing the petcock packing (4 hole) gasket, would complete the job. The bike is going to run onto the Reserve at about 3/4 tank down from full. That is the way it is designed.
The function of the brass tube sticking up is to capture fuel from the top half of the tank, then when the level drops below that point, you need to switch to reserve, which will pull fuel from the bottom of the petcock body/fuel tank.
A cleaned petcock can't really go "bad" if all parts are correctly installed and a new packing gasket put in.
The other thing that can happen with the fuel system, similar to that, would be the gas cap vent hole being blocked, which will create a vacuum in the fuel tank, until the cap is opened or pressure is otherwise equalized.
Bill Silver
