My classic 350CC is a months old and 1st service is done. Post 1st service in the recent days i have expereinced an issue that when bike is in moving condition it automatically stops. The fuel tank has close to 6 ltrs of fuel and set the fuel nob to ON. I immediately changed the fuel nob to Reserve and the bike started running as usual without any problems. Then I changed the fuel nob to ON and bike started working for say 2 to 3 KMs and then bike started to stop. I had to immediately move the fuel nob to Reserve for it work.

Note: The Bike never stopped when it is in Reserve mode.

Why Am I facing this issue? Any suggestions or fix?

  • Does it have a vacuum operated petcock (is there a hose going to the airbox)? What are the available settings on the petcock?
    – raydowe
    Commented May 31, 2017 at 7:57
  • I'm facing the issue , my 350classic two weeks old and I can't raise the accelerator . It is sounding like to be getting off. And if I change gear and move again same issue. Bs4 engine sucks
    – Chakri
    Commented Dec 5, 2017 at 12:05
  • friends I WAS ABOUT TO POST about the same issue when I found this posted by someone. So I would like to say that mine one is BS3 9 months old 2700km driven and I am facing this problem since I got my bike serviced from authorized RE dealer. When fuel lever is at ON position then bike shivers just like it does when fuel is short and then suddenly stops. When I changed it to reserve then it perfectly runs alright. First I thought my bike was giving low mileage but it actually was giving 41.7km/l since the tank went nearly full(since I kept on refueling it). I will try the above remedy. Commented Dec 24, 2017 at 18:58
  • how much is the reserve fuel capacity of your bike.?Have you tried filling in more fuel and checked if it is still not allowing you to operate your vehicle in ON position?
    – DhKo
    Commented Dec 26, 2017 at 6:28

2 Answers 2


It sounds like a fuelling issue, where your petcock isn't allowing enough fuel to flow into the carburetor when in the on position. When the bowls are full the bike will run for a while, but eventually the level in the bowl will drop to the point that the engine stalls.

Fuel petcocks are usually operated by a vacuum. There is a rubber diaphragm inside, and when the engine runs, a hose connected to the air box provides a vacuum on the back of the diaphragm. This pulls the diaphragm open, and allows fuel to flow freely. When the bike stops running, the diaphragm closes, and prevents fuel from continually flowing into the carburetor. If your float bowls ever get stuck open, this will stop your entire tank of gas from ending up on the pavement. When you use the reserve setting on the petcock, the diaphragm is bypassed, and fuel is allowed to flow to the carburetor.

I would check the vacuum line. There should be one that runs from the back of the petcock to the air box on the bike. Check that it's connected, and that it isn't cracked or otherwise damaged. If you don't find the problem, I would investigate the petcock itself. It's possible it's damaged or improperly assembled in some way.


Depending upon the design of the fuel tap it could be blockage in the tap itself.

I would test this by disconnecting the fuel line from the carburettor to see if fuel flows. Have a container ready to catch the fuel.

You could also try blowing back through the fuel line. With the fuel cap removed that should not be difficult. Be careful not to swallow or injest any fuel. Use a compressor or large syringe if possible to avoid injesting fuel.

If nothing flows, and/or you cant blow throught it the tap may need to be removed and cleaned or possibly replaced.

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