Case Reed Induction 250

[1982 XC 430]

As far as I can tell Husqvarna never jumped on the bandwagon of the early 80's like the Japanese with the case Reed induction. The interweb also has a lot of people with the usual grips and groans as to whether it did good or harm. None the less the KTMs of today use them and there power seems to lead the way. So if Husqvarna never used it, did Cagiva ? And if so did they wile they were still using the traditional Husqvarna lower end. As in with the same Motor Mounts as our 82 and newer bikes ?

 

[justintendo]

there are some pics floating around of swede prototypes with case induction..
seems like if husky stayed in sweden, the 89/90 or so 2 strokes would have had it along with electric powervalves across the board. the pv did just sneak in in the last cr250.
cagiva scrapped all swede 2 stroke design and continued their 4 strokes, instead using the italian 2 stroke in its place.

 

[Kartwheel68]

KTM went to it first with a hybrid system '81-'83 and full case reed in '84, the Japanese went back and forth in the '80s but by '90 everything was case reed. Today, I am not aware of a race 125 that is not case reed.

As to your question on the Husky, I dont think Cagiva ever used any Swedish 125 parts, from '87 on the 125 was 100% Italian.

 

[fran...k.]

Could not the 87-88 and perhaps a bit earlier 250 two strokes be called hybrid? I seem to recall the transfers connected to the reed cage area and perhaps a way around the piston down low. Not enough room in the larger bore two cycles.

The elimination of the long rods that go from the case to the head probably is more of a hindrance than where the reed cage is located. The Yamaha 250 two cycle still has the reed cage attached to the cylinder. Not sure how far if any it is behind Ktm with similar rider and set up. The way it looks to me is the case reed as currently used in motorcycles has less holes/hole area in the sides of the cylinder but the rear of the piston is trimmed more. The modern 125 has all been case reed for a while best as I can tell.

 

[Kartwheel68]

The hybrid KTM125 actually had a reed cage that bolted to the case and cylinder and sent half the charge to the cases and half to the cylinder. There have been a few 250s with case reed induction but it does not work as well as on a 125. All modern 250s are non-case reed as far as I am aware.

 

[Kartwheel68]

Another interesting engine feature, all modern 125s are 54x54mm bore and stroke. The Sachs and Zundapp 125s from the early 60s were 54x54mm while Husky and all the Japanese fiddled around with oversquare engines in the 56x50mm range until the late 80s, about the same time they went to case reed.

 

[Norman Foley]

The hybrid KTM125 actually had a reed cage that bolted to the case and cylinder and sent half the charge to the cases and half to the cylinder. There have been a few 250s with case reed induction but it does not work as well as on a 125. All modern 250s are non-case reed as far as I am aware.

I think you have this backwards... Pretty much all modern 250's are case reed. I'm not sure you could call an Italian Husky WR250 "modern". When the last '14 rolled off the line, that Cagiva engine was over 25 years old.

 

[1982 XC 430]

OK, so what is the real advantage to Case Reed Induction ? Since most of the manufactures went back and forth for a wile it must not of been that big of a deal. Kinda like Up side down Forks.
I see the new KTM 250's have a longer stroke than our Husqvarnas. With our low end and mid range I would of thought our bikes had the longer stroke. Although my 2000 MXC has some pretty good low end grunt.

 

[justintendo]

OK, so what is the real advantage to Case Reed Induction ? Since most of the manufactures went back and forth for a wile it must not of been that big of a deal. Kinda like Up side down Forks.
I see the new KTM 250's have a longer stroke than our Husqvarnas. With our low end and mid range I would of thought our bikes had the longer stroke. Although my 2000 MXC has some pretty good low end grunt.

the 87-88 husky 250 went to undersquare design, compared to the oversquare all husky 250s had been...the result was better bottom end and mid..
one advantage of case reed induction is not having the restrictions of trying to jam the reeds into the cylinder, and working around cylinder studs or bolts. even with your reeds mounted on the cylinder the charge goes straight to the crankcase anyway..the case reed setup apparently is a more direct path.

 

[Kartwheel68]

I think you have this backwards... Pretty much all modern 250's are case reed. I'm not sure you could call an Italian Husky WR250 "modern". When the last '14 rolled off the line, that Cagiva engine was over 25 years old.

The KTM250 is case reed, all the Japanese 250s are non-case reed. Looks like Beta and GasGas are also case reed. For a 250 I dont think there is much advantage one way or the other.

OK, so what is the real advantage to Case Reed Induction ? Since most of the manufactures went back and forth for a wile it must not of been that big of a deal. Kinda like Up side down Forks.
I see the new KTM 250's have a longer stroke than our Husqvarnas. With our low end and mid range I would of thought our bikes had the longer stroke. Although my 2000 MXC has some pretty good low end grunt.

The Japanese settled on undersquare 66x72mm, I think Yamaha was the last of the Japanese to go to that bore and stroke in '99, and its pretty much universal now, even small companies like GasGas use the same bore and stroke for their 250s which interestingly is the bore and stroke of all Maico 250s back to the mid 50s. I think for two strokes bore and stroke is over rated as a factor in power, I think cylinder porting is far more important to power delivery. Look at the '81 and '82 250CRs, same bore and stroke and they have completely and totally different power characteristics. Case reed, in theory, will make more power because as justintendo said, the fuel charge has a straight shot right into the cases, but in practice it puts that power more towards the top end at the sacrifice of low end, which is why it is preferred for 125s and not as common on 250s. I dont believe there has ever been a 500 dirt bike with case reeds, but KTM380s were case reed being developed from the 250 platform.

 

[troy deck]

OK, so what is the real advantage to Case Reed Induction ? Since most of the manufactures went back and forth for a wile it must not of been that big of a deal. Kinda like Up side down Forks.
I see the new KTM 250's have a longer stroke than our Husqvarnas. With our low end and mid range I would of thought our bikes had the longer stroke. Although my 2000 MXC has some pretty good low end grunt.

WELL YOU CAN PULL THE TOP END AND NOT TOUCH THE CARB IT SEEMS TO ME THAT CASE REED WOULD BE BETTER BUT WHAT DO I KNOW

 

[Norman Foley]

Only one modern Japanese 250 2T engine left... YZ250 and yes it's cylinder reed induction.

That still makes the majority of modern 250 2T engines case reed induction, including TM....

 

[Kartwheel68]

Suzuki and Kawasaki still sell their 250 2Ts everywhere in the world but North America. Honda is the only one who doesnt offer them at all anymore.

 

[Norman Foley]

Suzuki and Kawasaki still sell their 250 2Ts everywhere in the world but North America. Honda is the only one who doesnt offer them at all anymore.

I checked 3 major off road markets... UK, Italy and Australia. The RM and KX250's are not available in any of them. Not to say they are not available somewhere. Hard to navigate Kawasaki Japan site, but can't seem to find KX250....

 

[2premo]

one of the biggest advantages to case reed is a more complete charge without the turbulence of the piston port issue
my KTM 380 has a case reed but the power is not dramatically greater, except that its larger cc, power per cc is not any better or more linear
seems to matter more on the smaller engines that need full charge for the power

 

[fran...k.]

Your ktm 380, at least the way it comes originally does not have a filled crank.

 

[Kartwheel68]

I checked 3 major off road markets... UK, Italy and Australia. The RM and KX250's are not available in any of them. Not to say they are not available somewhere. Hard to navigate Kawasaki Japan site, but can't seem to find KX250....

I guess the Yamaha is the only one left now, as little as a year or two ago you could still get the KX and RM. Probably not much demand in Europe for those bikes since all those other European brands have bikes that are being developed instead of a 10+ year old design with new graphics.

 

[Norman Foley]

I guess the Yamaha is the only one left now, as little as a year or two ago you could still get the KX and RM. Probably not much demand in Europe for those bikes since all those other European brands have bikes that are being developed instead of a 10+ year old design with new graphics.

Italy is a big market for Japanese off road bikes... Importers of the big 4, do street legal enduro conversions on the available MX bikes.

 

[troy deck]

DONT KNOW BOUT 250S BUT YOU SEE YELLOW AND GREEN IN EMX125

 

[2premo]

Your ktm 380, at least the way it comes originally does not have a filled crank.

what do you mean by "filled crank"?