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Reed valve question. Small gap

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I am in the process of doing a rebuild on my 2007 YZ250. The cylinder is in the UPS truck headed to Eric Gore. He suggested an evaluation and the do work as needed. I am sending out the crank to Andrew Cooksey for a rebuild. That pretty much leaves sending out the head to RB Designs when I get it back from Eric Gore, unless he modifies it himself and then the reeds.

There is a small gap in one of the 4 reeds. There is nothing physically blocking the reed up so I figure it needs replacing. Should I go with an OEM set or a set of Boysen Super Stock reeds? From what I understand Only the Boysen Rad set requires a new valve body and the Super Stock use the original Valve body. Also, it sounds like I need to remove the valve stops and install the little bars that come with the reeds. When I look at the oem reed assembly from inside the jug, it looks like there is not much room for the reeds to open much further then the stops allow. So will the impact the cylinders valve opening? It just looks really close. Can the Boysen reeds be run with the stops?

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Reeds really dont travel that much from full open to close, its their ability to do so precisely and without fluttering etc that is really important.

depending upon what you are trying to accomplish and the type of reeds you can flip the reeds over, simple and you will see if they close tight against the cage.

also, you may want to have new reeds on hand (if the reeds are open they maybe stressed to that point and if you have enough hours on the bike that you are doing a complete rebuild, and those are stock reeds, its time to change out anyhow.....but have them on hand and then once you get the Eric G special back you can swap them out AFTER you see what his work has done.

THEN swap out the reeds

lets you know where the motor is performance wise before any intake changes. Change them all at once and you wont really know what is doing what to your power delivery.

Eric I know has dont some evaluations on the Boyesen set up, and there are lots of folks that love the V Force reeds....

Good Luck


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