Carb question HP500 blue engines
 

This is out of curiosity more than anything.

I'm renewing both my carbs and have found black 50cc diaphragms in the front and green 50cc in the back on both. They've never been opened and came installed on the engines from Merc racing.

I called Holly and the tech help said they were not from Holly that way, I'm thinking he was assuming and too busy to care. So I'm ordering greens for the front (no black in kit) and calling it done. Just wondering the logic behind this and WHY you would not just use the greens (alcohol safe) in all applications?

either will work fine, the ones for alcohol are drag racing and running strait methonal...somebody did change yours..