I have been seeing lots of talk here in the forums about Reeds. What are they? What do they do? Can any one enlighten me on them.

Reeds act as a one-way valve between the carburettor and the crankcase and are found in most modern two-stroke motors. Having a one-way valve there means that the volume of air/fuel mixture drawn in can be maximised without limiting the induction timing. Many older two strokes don't have reeds and used the rear bottom edge of the piston to close off the inlet port to prevent the air/fuel mixture going backwards as the piston descends. This makes for a more restrictive flow path than what is possible using a one-way valve (reeds)

In your bike the reeds are thin, stiff plastic composite flaps that are fixed only at one end. They flex inwards when open and seal against a flat seat when closed.

There is a slight pressure drop through reeds which is why for ultimate high performance in two-strokes, a rotary valve (which does not cause a pressure drop) is often used to control the induction timing instead of reeds.

Ok that makes sense. So how old are you talking about? Would a 94 techno have reeds or not?

Most 2 stroke engines have had reeds since the late 1970's early 1980's.

Although i cant comment on your particular model, i would be very surprised if it hasn't.

I have not had to dig that far into the engine of my bike as of yet but thanks for all the info on the subject guys

Considering the age of your bike and its service record which you have shared with us It would be a good idea to remove the reeds on your bike and have a look at them. You need to remove the carburator to gain access to them. Their screwed onto the plastic block that you see between the rubber intake manifold and the engine case. Once you get the reed block out of the motor look to see if the reed petels are chipped or cracked. Also look to see that they are sitting down tight against the reed block. If they are worn they need to be replaced. If they do not rest tight against the reed block you may be able to fix them by flipping them over. Use thread lock on the screws upon reinstallation and be aware not to overtighten them because if you overtighten them the reed petals will curl and lift off the reed block at the tips and not close properly. If after flipping them they do not sit down tight against the reed block they will need to be replaced. When reeds are worn the motor will loose bottom response and torque and the motor will become hard to start.

Edited February 9, 201115 yr by Liviob

Im not having any of those issues with my techno. Its running like it was new. I just had no idea what they were and thanks to all your help i now am more knowledgeable about them however i will keep that in mind for future maintenance.

If your bike is running fine then ofcourse no worries. Just for reference info. I am currently refreshing an 01 REV3 250. Since i had the topend off the motor I pulled the reed cage out to inspect the reeds. I noticed that the reed petals were not making a good seal against the reed cage. I flipped them but they still would not make a good seal against the cage as they had deformed some through the years since 01. I had to replace them with a new set to get a good seal between the reeds and the reed block.