A common failure on Yamaha 2 strokes bike (like RD500LC / RZ500 / RZV500R and RD350 / RZ350) is the leak of 2 stoke oil from the pump to the crank case due to one way valve failure.

The idea is to use a petcock on the oil line between the tank and the pump. But we don’t want to ride the bike with the petcock off.

Then, the solution is to put a switch on the petcock which acts like a kill switch. I’m planning to use a standard fuel petcock (figure below)

A reed switch will be used to avoid mechanical contact and it will be Normally Open one because in case of failure the bike can be started. The reed is activated by a magnet.

Done come CAD and design the plate holder and a new lever. The plate bolt on the petcock and the switch is located in it. The lever has a magnet to activate the switch.

A first prototype has been 3D printed in PLA to validate the concept. The original lever can also be used (see picture below printed lever and modified petcock)

Experiments

The design needs to deactivate the kill switch only when oil flows for sure

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