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Pulse Pump

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mstull

R.I.P.
Joined
Jun 23, 2005
Messages
1,263
Location
West Texas
I have a question about Mikuni pulse pumps. I read in a U/L magazine years ago that the tiny bleed hole in the pump is important, and to check for it. But the last two "single" pulse pumps I've bought didn't have that hole drilled. There is a little divot in the casting where it goes. But no hole was drilled by the factory.

I put over 100 hours on one of those pumps before I noticed it. And it always worked fine. I can guess a reason or two for the hole. But does anyone know for sure its function and whether it's really important? I assume the factory knows the pumps they're selling don't have them.

On some installations, two stroke oil can accumulate in the pump until the whole (pulse side of the diaphragm of the) pump is full of oil, and even the pulse line can gradually fill with oil. Noticing oil in my pulse line led me to check for the hole. I used a micro-drill bit to add the hole to my present pump. A #60 drill bit is way too big.

Do the double pumps still come with the hole?
 
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