Reeds?

[mike-evans]

What do reeds do, and what part do they play in starting the bike? What problems wil you have if they are worn out?

 

[dirt bike dave]

Here is a link for you: http://www.ret-monitor.com/articles/1332/reed-valves-for-two-stroke-induction/


If they are worn out and not sealing, you can get compression leaking back out the reeds, and maybe too much fuel/air getting in on the intake stroke.

Mostly you will notice this as hard cold starting, loss of low end power and poor throttle response.

I think Yamaha was the first one to really popularize reed valves, about 1970+-. Other makers like Can-Am, Suzuki and Kawasaki used rotary valves to accomplish the same things, but reeds soon became the standard.

 

[2strokerfun]

I learned about what a reed valve does from Cox .049 engines back when I was about 8 years old. I also learned how to drill holes in plastic and lace with safety wire, mix epoxy and melt plastic back together with mom's Zippo about the same time (in addition to learning how much a little propeller hurts when it hits ice-cold little fingers Christmas day). I'll bet I wasn't alone, either.

 

[mike-evans]

Just phobed my local Yamaha dealer to order a reed valve.gasket (between rad valve and cylinder) and he told me the genuine one doesn't have a gasket?? I'm yet to have a look, but how does it make a good seal, because the rad valve I'd made of rubber?? Is that good enough?

Will boyesen reeds fit my standard rad valve?

 

[whenfoxforks-ruled]

Doesn't Boyseen make the rad valve? And yes, it should have a rubber seal cast into 1 side.

 

[IndyMX]

Just phobed my local Yamaha dealer to order a reed valve.gasket (between rad valve and cylinder) and he told me the genuine one doesn't have a gasket?? I'm yet to have a look, but how does it make a good seal, because the rad valve I'd made of rubber?? Is that good enough?

Will boyesen reeds fit my standard rad valve?

Boyesen does make stock replacements.

 

[mike-evans]

Just removed my rad valve to check my reeds, and they are very slightly lifted on one side, checked it with feeler gauges and its 0.1mm, factory manual spec is 0.2mm, so reeds are fine....

 

[RM_guy]

The spec may say it's OK to be lifted but I'd replace them if I were you. They are starting to go and you are loosing power in the condition they are in now.

 

[mike-evans]

The spec may say it's OK to be lifted but I'd replace them if I were you. They are starting to go and you are loosing power in the condition they are in now.

Ok wil order some up....

I'm on standard jetting and suffering from spooge so going to drop my pilot from 55 down to 52, will it be ok to do this and put new reeds in at the same time and not cause a lean condition?

 

[whenfoxforks-ruled]

Change 1 thing at a time, or you may never know.

 

[mike-evans]

I'm picking a smaller pilot jet up tomorrow, just checked my air screw position, and its 2 1/4 turns out, does that mean a smaller pilot is needed?

 

[RM_guy]

Yes you need a smaller pilot. I do agree with fox though, see how it runs after the new reeds before changing the pilot.

 

[mike-evans]

Well I've just picked my 52 pilot jet up, and after reading this just ordered some Boyesen reeds, probably best to stick the new reeds in and try that before I change the pilot?

Once the reeds are in, what shall I do with the air screw as its 2 1/4 turns out now, take out back to standard settings or leave it?

Will it be to lean once new reeds are in and air screw is left where it is now?

 

[whenfoxforks-ruled]

You need to fix all the possible mechanical issues, before attempting to jet the bike. That includes the reeds. Over tighten the reeds, and they can buckle up, and measure out of spec. Be careful. I would not mess with the air screw, until its started up, then adjust it after its warmed up and cleared out, if possible? You may need to adjust the air on the stand, if its far off. But it will change after its cleared out. You are not that far off right now, at 2 1/4. But?