Well the klx250 has a stout bottom end, basically from the 450, they just made it smaller and put on a 250cc jug. I'll look up the specs of the 450 bore and stroke and see what I can find

klx250 boreXstroke is 72.0X61.2 mm

kx450f boreXstroke is 96X62.1mm

So the klx351 has a boreXstroke of 85.4X61.2mm, now if we were to take that and raise to a 62.1mm stroke we are left with like 356 cc not worth it at all sadly...with these small engine stroke does not effect CC as much as a multi cylinder engine would.

To get 401cc would have to raise the stroke a whole 8.8mm!!! That's 70mm stroke!! If it is possible, that would be a cool prospective...

 

Stout, yes. But from a 450, not at all. The KLX250 has the bottom end of a KLX250.

The KLX250S has a dated engine, its lineage goes back to the KLX250R which was a clean sheet design in 1993. The KLX250R morphed into the KLX300R in 1997, which was unchanged until the end of production in 2007. In 2006, the KLX250S was introduced, related very closely to the 250R/300R, but with several differences to make it an electric start dual sport. There are also the closely related D-Tracker models overseas, but I don't know much of anything about them.

Back when the KLX250/300 engine was a 'modern' technology (basically the mid-90's, before the YZ400F came on the scene), there were several hop up companies offering big bore and stroker engine kits...292cc, 301cc, 320cc, 331, 340, 365. I believe 365 was the biggest combination anyone ever offered for sale. All the current big bores are based on the development done long ago, except for the 351 offered by Bill Blue which is new. Big bores have always been a cheap way to boost engine output, but the stroker kits more or less died off because the expense and factory production of much higher performing bikes with less investment.

 

Monsta: I’m not concerned about the plastics. When I break one, I’ll replace it. I ride a lot of single track trails and the brush scratches them up good. Not to mention laying it down from time to time. It don’t have to be pretty!
Not sure the difference between the new and older KLX’s. This is my first off road bike since 1975.
The track I ride is about 6 miles long. It runs through and around a major functioning sand and gravel mining pit. We use it for a Hare Scramble every year. It has MX, flat, single and double wooded, and open terrain. The KLX holds up nicely. Obviously it can’t keep up with the YZ’z, KTM’s and other similar machines, but I’m very happy!

 

I miss spoke, from what i gathered it can handle te powerfron a 450, i didnt mean it was the same. Wrong choice of words

 

Dated engine? Here I am thinking this thing is a space ship compared to the 85 xr200 I had previously.

Makes sense but I still want one.

 

So I hit 100 miles today with some aggressive trail riding mixed in. It's super fun and easy on the road. I just tried a 2nd gear wheelie and with a light tug it comes up, just need to find the sweet spot now. The cheapo suspension feels like the ninja 250 I took trail riding years ago. It's fine for the rough stuff just need to go a bit slower unless your a mad man.
My neighbor has a cr250f I was eyeballing the suspension and will have to make a few measurements.


On another note I contacted Dobeck performance and ordered a Gen 4 arf plus for the CRF. Its the EFI controller with an A/F ratio gauge. They do not make it for the CRF but were happy to load the programing/specs on it to suit my application. It comes with a wideband O2 sensor so If it's the same thread I will replace the stocker as it is bypassed anyway if not I have to weld a bung somewhere. Either way is fine but does anyone know if it would be the same size thread? Also could I power the unit up and just use the O2sensor/gauge to tune the KLX? If anyone is interested in putting one on the FI KLX just E-mail/call them I'm sure they can help out.

 

That's exactly what people were thinking back in '93! After all, the KLX250R was a marvel in technology when it came out, pretty much the first mainstream four stroke dirtbike with liquid cooling and dual overhead cams.

 

Since there is no CR250F do you mean CRF250R or CRF250X? If so they are not even close to compare to your CRF250”L”. Like I said before just because it says “CRF” doesn’t make it a racing bike. That is like Kawasaki calling the KLX250S a KXF250S. Or Suzuki renaming the DRZ400S to RMZ400S. Hondas marketing scheme………..

 

Sorry I had the model wrong it's a crf250r it's my 15 years old neighbors bike thought thats what he had said it was. Mabey I was confusing it with the cr250 he traded it for.

I promise I am not a twelve year old with high expectations of the CRF branding and I am fully aware of the differences between the two. I never said I was comparing bikes or anything just that I was checking out his suspension because the CRF is really lacking. Something is going to fit the stock 250L tripple clamps probably another Honda XR CRF CR model, hell the KLX is just a smidge thicker and could probably squeek in there.

I appoligize if my post has evolved from a might sell situation to an informative comparison. As I own both bikes I am excited to share information and thoughts about the similarities/ differences etc. I was never trying to Lay a coat of Honda red on the Kawi forum just trying to cure my case of cabin fever.

 

I appoligize if my post has evolved from a might sell situation to an informative comparison. As I own both bikes I am excited to share information and thoughts about the similarities/ differences etc. I was never trying to Lay a coat of Honda red on the Kawi forum just trying to cure my case of cabin fever.[/QUOTE]