Performance reeds: How do they increase power and do they decrease fuel economy?

[VenomRS4]

As stated in title. I'm having an argument at my place of work and I may be wrong. So I need an answer from some pros! How do they work? And at wide open throttle, I understand an engine with performance reeds will have more power. Will it also use more fuel while doing it compared to an engine with stock reeds at wide open throttle? Thanks!

[RIDE-RED 250r]

Well, it's been my experience that performance reeds are more of a supporting mod to other, heavier mods. Just throwing a set of aftermarket or "performance" reeds into a stock or near stock engine will net you pretty much zero noticeable power increases. Granted a slight gain may be seen on a side by side dyno comparison, but you won't feel it in the seat of your pants. In fact, in the case of a stock or near stock engine, jetting changes are rarely needed. If you don't have to up the jetting then what are you really gaining? About the only difference I have ever noticed with reeds is a little snappier throttle response, and that is very subjective as the reeds I replaced may have just been a little worn and the new reeds woke it back up.

There are people/companies out there who make some pretty tall HP gain claims. But, if you read the fine print you will see that the gains they claim to have seen on the dyno were their reeds used in conjunction with other mods.

[Scootertrash]

What Ride-Red said. I have heard that reeds don't do much for power, it's more for throttle response. A more flexible reed will open and close faster.
My guess with the power part of the claims is that the power is created by the other mods, and a more responsive reed lets the motor develop the power faster by allowing the fuel/air mix into the cylinder quicker.

As far as horsepower gains from bolt on mods, If you read the claims carefully most of them say something to the effect of "Up to (insert number) horsepower increase". The "up to" is the key phrase. ;)

[Mosh]

Reeds do nothing for adding horse power, unless you are replacing stock steel reeds, that take more effort from intake draw to operate. Also removing the stopper plates will let them open further in theory.
Reed's basically move power curves around, unless you install or modify a larger cage in conjunction with jetting and carb work. Many reeds are designed to add low end hit by adding a second layer of stiffer pedals over top the first layer, to make the engine pull more lower RPM torque. You see that more with small bore 2 strokes.

If you picture what a cam and valves do for a 4 stroke with intake and Exhaust duration and valve lift, most of that, is accomplished on a 2 stroke in jug and piston port timing..The reeds have nothing to do with adding power..If you want more power on a 4 stroke, you play with cam and porting..To get that same effect on a 2 stroke, you port your jug..All reeds do, is let the engine hit into the topend sooner or later. On a bigbore/stroker 2 stroke, reeds could come into play some with adding power, but mostly the cage size and flow is what matters to assist the stroker bigbore engine.

As far as fuel mileage, honestly who could, or want to waist the time in even trying to calculate it. The variables and outcomes are too inconsistent and subtle to even compare..

[RIDE-RED 250r]

Reeds do nothing for adding horse power, unless you are replacing stock steel reeds, that take more effort from intake draw to operate. Also removing the stopper plates will let them open further in theory.
Reed's basically move power curves around, unless you install or modify a larger cage in conjunction with jetting and carb work. Many reeds are designed to add low end hit by adding a second layer of stiffer pedals over top the first layer, to make the engine pull more lower RPM torque. You see that more with small bore 2 strokes.

If you picture what a cam and valves do for a 4 stroke with intake and Exhaust duration and valve lift, most of that, is accomplished on a 2 stroke in jug and piston port timing..The reeds have nothing to do with adding power..If you want more power on a 4 stroke, you play with cam and porting..To get that same effect on a 2 stroke, you port your jug..All reeds do, is let the engine hit into the topend sooner or later. On a bigbore/stroker 2 stroke, reeds could come into play some with adding power, but mostly the cage size and flow is what matters to assist the stroker bigbore engine.

As far as fuel mileage, honestly who could, or want to waist the time in even trying to calculate it. The variables and outcomes are too inconsistent and subtle to even compare..

I ride alot of seasonal roads on my R where you tend to spend more time in the higher gears. I used to get 30-35mpg with my old, semi-stock setup.. My 350 with the goodies on the other hand gets 20-25mpg! LOL! I don't really care what my MPG's are, I'm out there to throw some dirt around and have some fun. But knowing about what it gets does help in knowing how far I can ride. Nobody wants to get brought back to camp on the end of a rope behind a quad even if it is just because you ran out of fuel! LOL! Been there, bought that T-shirt.. :beer