Author Topic: “Check Valves” location  (Read 251 times)

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Offline Stoneman

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“Check Valves” location
« on: April 25, 2022, 12:40:43 PM »
If I’m reading the parts manual illustration correctly, the check valves are built into the bolt that’s part of the oil tube banjo connection assemblies?  Understand the valves are a small ball and spring that opens, closes regulated by positive/negative pressure in the oil line generated by the piston stroke.  Do I have this right?



Offline OldSwartout

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Re: “Check Valves” location
« Reply #1 on: April 25, 2022, 02:27:29 PM »
Yes. The check valves keep oil from seeping through the pump into the crankcase when not in use, and also keep the crankcase vacuum from pulling in more oil than is supposed to be pumped.
Karl Swartout
Mooresville, IN
BS175 Roadracer. BS200RS, BS175HS

Offline BRT-GTR

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Re: “Check Valves” location
« Reply #2 on: April 26, 2022, 10:32:26 AM »
    Some additional information to the above :-
                                           Be careful when unscrewing the checkvalves. Because the 8mm brass bolt is drilled to accomodate the check ball and spring, they are very fragile and often shear at the base of the thread when unscrewed. And they are relatively expensive to replace.

   The ball is arranged to provide a positive stop which prevents crankcase +ve pressure from pushing oil back towards the pump.

   The oil pump pushes the ball off its seat, against a very light spring pressure, and a slug of oil is (injected?) more like dribbled! into each alternate cylinder for each revolution of the pump.
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