Quote:Can anyone explain the mechanics behind it please? I ask as my old machine runs as rough as a badger backside and I am tempted to put a genuine petcock on.
A petcock is nothing more than a valve that lets fuel run run from the tank into the carb.
The raptor is manual. Turned to either ON or RESERVE it lets fuel flow. Turned OFF it shuts of the fuel, just like turning off a faucet.
The OEM petcock requires engine vacuum from a port on the carb- to pull on a rubber diaphragm built into in the petcock to open the fuel passage when the lever is either in the FUEL or RESERVE position. That's the reason for the vaccum line from the petcock to the carb. There is only vacuum applied to the diaphragm when the engine is running. When the engine is not running the petcock shuts itself off. The only reason for the extra complication is so that you don't have to remember to turn the fuel OFF like you would with a manual valve like the Raptor. When the stock petcock lever is turned to PRIME, the fuel passage is always open however. In that position the valve cannot be shut off.
When you install a Raptor you need to plug the vacuum port on the carb.
If your bike is not running right with a Raptor, and you have that port on the carb plugged, switching back to a stock petcock is not going to fix anything. A properly operating stock petcock and a raptor do exactly the same thing; they let the gas run from the tank into the carb. That's all.
The stock unit is known to malfunction and cause problems sometimes. That's why people switch to the Raptor. If the stock petcock is not malfunctioning a Raptor isn't going to change anything except that the Raptor won't shut off automatically when the bike is turned off. You have to turn the lever to OFF by hand.
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