05 CR250 and CR125 news.....Just out

[Rider 007]

Case reed engines can produce bottom power...It's just that the case reed engine will tend to have a better upper mid and top end...

The KTM got better low end than the previous year but it still is more of a upper mid and top end running engine...

I understand that the conventional wisdom is that a case reed is more conducive to upper-rpm power, but there are too many examples of them making solid bottom or all-around power to blame Honda's "woes" on the engine type.

As far as the KTM still being more of an upper mid and top engine, I'll repeat the quote from DB, the same mag that said the 03 CR250 had "weak bottom end power" and "The CR truly labors at low rpm." (DB, Jan. 03)
DB, Jan. 04: Regarding the 04 KTM 250SX: "Now it comes on very strong on the bottom...", "...use the crazy low-end power", "Great torque".

That doesn't sound like and engine that "is more of an upper mid and top end running engine..." to me. Nor does the following quote from MXA:

MXA, Feb. 04: "KTM is an easy third - and not more than a hair behind the RM and YZ in overall power, (although it needs more top end.)"

Huh? Doesn't sound like the high-rpm type of engine they claim the case reed design is. Sounds like the opposite.
They are making my case for me, yet they keep saying "blame it on the case reed engine" for the CR.

What I want to know is how does KTM (and others) get a case reed to produce good power and what does Honda need to do to cure theirs?
How can KTM have a good running case reed and yet MXA will ignore this fact and blame Honda's low end on the case reed design? :bang:

Am I still sane? :eek:

:ride:

 

[john3_16]

Yeah....I see you point....The CR is very powerful though...It just needs some low end....It seems like Honda could do something just a little different to bring it down a little....Maybe it's the power valve ?

 

[marcusgunby]

They have too big ports-have been the same for a while-just like the 125.

 

[kbob]

the information is the new law going into effect it just doesnt effect are dirt bike, but also diesel trucks, lawnmowers,cars.The place to look for it would be the epa website.The other thing is honda already has a clean burning two stroke seen the motor in a dirt bike magazine a few years back.the question is will they put it in to productionhttp: This is a link that clearly shows a yz 250 model to be sold in europe.//www.yamaha-motor-europe.com/products/motorcycles/competition/competition_overview.jsp and here but you may be right the us does probably have the lions share of the market but will still be buying them also for closed competition.

 

[Rider 007]

They have too big ports-have been the same for a while-just like the 125.

I suspected this since I was hearing that most of the hop-up shops were machining the base of cylinder as part of their mods. I figured it was to correct "overporting"... the ports were too high.

What are the affected ports?

Makes you wonder why someone hasn't come up with a way to weld up the ports, replate and retime them.
Or cast a new cylinder like Athena did for the YZ125. And it's cheaper than the OEM one.

:ride:

 

[marcusgunby]

You could reconfigure the ports but i think its more complicated to get it perfect, milling the base often has the right effect-ie more bottom less top so thats the prefered option-i dont think demand would allow a new cylinder casting.

 

[bedell99]

Marcus according to MXA the CR250 is still the best selling 2-stroke. I think the demand will always be there, but to design a entirly new cylinder must take mucho dinero. I think Athena's(YZ125) R&D was funded by a GP team. When there is a will(and money) there is a way.

Erik

 

[Rider 007]

Going back to the original post on this thread, on page 19 of the Sept. issue of DB they have printed a retraction regarding their pictures and statements about the 05 CR's.
The funny thing is that they said it was in the July issue and it was actually in the August issue! Even their correction is incorrect! :nener:
Just another example of the accuracy and effort that has been lacking in moto-journalism for the last several years. It seems like things are thrown together anymore and not checked for accuracy or even proof read, especially the minor stuff. Really sad. :think:

Back to the CR cylinder: If the base is milled it will drop the top of the ports and affect their timing. But it has no affect on their size or the volume or angle of them.
It seems that some of the expensive two-stroke design software should be able to model the needed design and show whether or not the cylinder is capable of being modified (within reason) or not.
I know you won't get trials type power, or even KDX type power out of an MXer without a redesign of the cylinder, but it must have missed the mark if they can't modify it to make it bark off the bottom without a new jug.
Heck, Suzuki finally got smart and just Xeroxed the YZ top-end! :eek:

:ride: