READ YOUR REEDS: MR. KNOW-IT-ALL

Dear Mr. Know-It-All,
My new-to-me 2007 RM250 won’t run properly. It runs super rich and stalls on every downhill. I can’t keep the thing running for the life of me. It has fresh fuel and a clean, well-jetted carb. It is a new issue that randomly popped up. Please help.
Tim Tearly
via [email protected]

Tim, Timmy, Timothy, you sound like a chap who loves your machine’s appearance but pays little attention to its vital organs. And, it sounds like having a two-stroke in your family may be a new thing? Now, etch this into your gray matter—your two-stroke inhales fuel/air through the intake when the piston rises in the stroke. Once the piston falls, it pushes the mixture through the transfer ports and into the combustion chamber. There is always some of the charge remaining and back-flows into the intake, and your machine’s reed valve performs the task of acting like a check valve that curtails the backwash of the unused air/fuel mixture. Reed valves use flexible reed petals that open and close, either on the piston’s ascent or descent, expelling the mixture on the engine side and sealing the reed block on the intake tract. These reed petals wear out, get chipped and lose their sealing ability.
This is your dilemma.
Purchase a new set of reeds. My suggestion is either Boyesen or Moto Tassinari. Both companies offer excellent product that will suit your needs quite nicely.
You really should have known.

If you don’t mind displaying your ignorance for the world to see, who are we to deny the opportunity?
Send evidence of your failures to
[email protected] or Mr. Know-It-All
Dirt Bike, P.O. Box 957, Valencia, CA 91380-9057