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Testing Reed Block petals

184 Views 4 Replies 3 Participants Last post by  RJL1983
Hi all
I hope everyone is well

I'm hoping someone may have some thoughts on the below.
I have a question regarding testing the effectiveness of the reed block and petals in situ. I've a 2005 RS50 (d50b1 engine) which is most of the way through a rebuild. I've completed a leak down test by sealing off both the exhaust and inlet ports, placed the piston at BDC and I've adapted an old compression tester hose to pressurise the crankcase through the spark plug hole. Everything is good and I can hold 8-9 psi for 30mins without any movement.
So I next removed the rubber blanking seal from the inlet side of the crankcase and put back the original reed block (with reeds) and tightened this down (using a gasket as normal)
My question is if I should be able to pressurise the crankcase through the spark plug hole and expect the reeds to prevent any leakage back out the inlet port - hope that makes sense. I'm working on the basis that the reeds should only allow the fuel mixture into the crankcase and nothing back out and therefore when I pressurise the crankcase through the spark plug hole I should be able to maintain that pressure if my reeds are working (eg no air should leak backwards through the read block?
Currently, when I test, the air comes straight back out through the reeds immediately and so I assume they need to be replaced - although visually I don't see any obvious holes\gaps. I was just wanting to make sure this is a valid test to check the effectiveness of the read block
Many thanks in advance
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Reeds don't make an air tight seal. Best way to test reeds is to look up through reed cage at a light. Very slight light should be visible. But no big gaps. You can flip the reed petals around and see if they will sit flush. Even brand new V Force reeds have a touch of light you cann see.
Great - thanks. I should be good to continue with the rebuild then. I might get some replacement reeds anyway but they do currently look ok doing a visual check so will probably leave it until I'm further into the build.
Many thanks
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