Hey guys - my 250R started recently to make a sort of funny noise when I'm on the pipe - sounds like predetenation - my dad says it is the reeds. He says that they are similar in function as valves are on a fourstroke motor.

If so - what are some good aftermarket reeds for my 250R?

Is it possible it could be causing this wierd timing-is-off type noise? When I get the video digitized later (maybe tonite), I'll post it and you all can hear it...

Thanks

 

i hope im wording this right

they are a one way valve that allows air/fuel into the chamber via the vaccum created by the destroke of the engine. dont be affraid to take off the old air box boot from the air box to the carb, pull the carb, and pull the reeds and cage out of the cylinder. it's a very straight forward process. check the reeds for any abnomalties most common would be if they arent sitting flat/flush against the cage. some people flip them upside down for temporary fixes but they are so cheap (30 bucks) that i would just buy new boyesens. all questions on boyesens reeds are explained in detail on their site and they have a picture install process you can upload( i believe its a PDF so make sure you have adobe acrobat). HTH

 

HA2 is right. When the piston goes up it creates a crankcase vacumm. This vacumm pulls air in and the reeds open. As the piston comes down, the vacumm is gone and the reeds close. The downward motion forces the air out of the crankcase and back against the reeds (which are now closed) and into the cylinder for combustion.

Reeds can get soft over time and not open and close fast enough. Boyesens are the way to go. Just follow the instructions. Remember, the reed stopper won't be used with the boyesens.