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Case reed vs Cylinder reed

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Does anyone know what the advantages/disadvntages of the 2 are? If you have some sort of detailed analysis that shows how they compare thats available online I would like to read it. Im wondering if there are gains to be made through case reed designs as we saw Honda and KTM switch to that design

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They always said a case reed would favor a top end motor, the cylinder reed type would be better for low to mid. If you look at the designs on a cut-away, you see how much longer the intake is on a case reed system.

The bad part of this is having the two bikes you picked as examples. The honda does not run well down low, or top, and the ktm rips low, mid and high.

I think in time they would have all gone to a case reed system as it allowed so many tuning options with regards to the intake volume. With our yz 250's its pretty easy to see how limited they were due to cylinder placement, reed placement, carb placement and airbox location. Whats left? Maybe an inch of for and aft movement?? The case reed would give another inch, at least.

I believe the case reed design would have given plenty of top end by design. Then electronic ignitions and powervalves come in to play and boost low and midrange. A good example of this is Yamaha's yz 125 which is a low end monster considering the piston is the size of a shotglass.

The design that really had potential was what Kawasaki and Can Am used, rotary Valves. I believe the extra width of the engine doomed the idea.

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Thats interesting, Ive read about the rotary valves in a few places and it seems like more of a weight issue than size. Those rotary valves usually weighed a bit more than the usual valve system

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A lot of the Ski-Doo 2T Snowmobile engines featured the rotary valve system, they were good performers but I can't say that they were a lot more powerful than the other sleds with reed valves.

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They always said a case reed would favor a top end motor, the cylinder reed type would be better for low to mid. If you look at the designs on a cut-away, you see how much longer the intake is on a case reed system.

The bad part of this is having the two bikes you picked as examples. The honda does not run well down low, or top, and the ktm rips low, mid and high.

I think in time they would have all gone to a case reed system as it allowed so many tuning options with regards to the intake volume. With our yz 250's its pretty easy to see how limited they were due to cylinder placement, reed placement, carb placement and airbox location. Whats left? Maybe an inch of for and aft movement?? The case reed would give another inch, at least.

I believe the case reed design would have given plenty of top end by design. Then electronic ignitions and powervalves come in to play and boost low and midrange. A good example of this is Yamaha's yz 125 which is a low end monster considering the piston is the size of a shotglass.

The design that really had potential was what Kawasaki and Can Am used, rotary Valves. I believe the extra width of the engine doomed the idea.

Just after the intro of the reduced-volume case-reed on the 2005 YZ125, for the 2006 model, Yami also reduced the squish of the head and the carb got one less bypass port that gave it:

1. cleaner burn; and

2. leaner mixture that boosted low-end response.

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Case reed engines are easier to work on. Leave the carb and reed cage on while you pull the cylinder.

I owned a 2002 CR250 (first year of Honda case reed). It sucked, not because of the case reed but because of the Mikuni carbuetor. With a Keihin PWK, it was a fine engine for off-road use. My 2006 YZ250 was no better stock.

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Case reed engines are easier to work on. Leave the carb and reed cage on while you pull the cylinder.

I owned a 2002 CR250 (first year of Honda case reed). It sucked, not because of the case reed but because of the Mikuni carbuetor. With a Keihin PWK, it was a fine engine for off-road use. My 2006 YZ250 was no better stock.

Then why didn't you keep it? :moon:

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