question for the KTM 250sx Experts...

Kinetic1
Profile picture for user Kinetic1
Posts
2796
Joined
6/4/2009
Location
Gun Lake, MI, USA
Kinetic1 12/7/2009 7:02am
12/7/2009 7:02am
Was it green? I was thinking the white one was the mellow one? The dealer should be able to tell him.
Deetsmx
Profile picture for user Deetsmx
Posts
888
Joined
4/21/2008
Location
Visalia, CA, USA
Deetsmx 12/7/2009 9:27am
12/7/2009 9:27am
On the 09, replacing the powervalve spring helps delay the hit a bit. Other than that, I thought it was a fairly easy to ride bike, just shift early cause it's dead up top. I had an 03 and that was the only 2-stroke I've ever had that would pull a 450's. Only problem was that it handled like crap and you could only hang on to it for about 2-3 laps before it wore you out and then the motor became a handful. It was one of the best bikes I'd ever ridden in the sand though, unfortunately there were no sand tracks where I raced. I sold it after a couple of months and got a Suzuki, which had a good motor but felt slow after riding the ktm. I have no doubts that ktm 250 had over 50 hp.
ratonmacias
Profile picture for user ratonmacias
Posts
1194
Joined
4/1/2008
Location
Guadalajara, MX
ratonmacias 12/7/2009 9:38am
12/7/2009 9:38am
i had a 03 250 sx and my brother had a 450 exc so we traded the triple clamps from both bikes the exc and the sx benefitted from the change also got the suspension done to terry hays' specs via munn racing wow night and day difference.

we used to ride many sandy dry creek beds that were full of berms that we made from riding so much the bike was a blast. one of my buddys had a husashit 650 enduro and he would love to start first and then go all jeff emig blocking the way only my sx was fast enough on the sand to corner quickly behind him and pull him under braking on the following berm.

it was the only bike i actually spent money to make it slower. power valve springs, pipe from the enduro bike flywheel weight. etc.
TeamGreen
Profile picture for user TeamGreen
Posts
37432
Joined
11/25/2008
Location
Thru-out, CA, USA
TeamGreen 12/7/2009 9:47am
12/7/2009 9:47am
55HP...Bwaaahahahahaha!

Gee...let me me know when a "Works" 250F makes 55...o.k.?

The Intro-Web..."Mystical"....

The Shop

See All »
williamsmotowerx 12/7/2009 10:04am
12/7/2009 10:04am
There's an Australian magazine... ADB I think that will be publishing a test.

YZ144, 250SX (2strk), CRF250... I won't tell you guys the results... I think that would be wrong of me since I don't think the article has been published yet... but you will be very surprised at which bikes was the "all around best"

I have a used KTM 250SX FMF pipe that is in great shape, PM me if interested.
TeamGreen
Profile picture for user TeamGreen
Posts
37432
Joined
11/25/2008
Location
Thru-out, CA, USA
TeamGreen 12/7/2009 10:06am
12/7/2009 10:06am
We always have a KTM250SX around the shop...

Easiest bike to ride 'fast'.

Period.

WhKnuckle
Profile picture for user WhKnuckle
Posts
7327
Joined
7/17/2007
Location
USA
WhKnuckle 12/7/2009 12:25pm
12/7/2009 12:25pm
50 hp, maybe, on a generous dyno. But 55? Stock CR500s only put out about 55 or 56 from the dyno runs I've seen (of course, they do it at 7500 or so). I'd take claims of 55 from a stock 250SX with a grain of salt...but whatever the number, the '02 - '03 250SX was a very fast bike.
Suns_PSD
Profile picture for user Suns_PSD
Posts
989
Joined
4/1/2008
Location
Austin, TX, USA
Suns_PSD 12/7/2009 12:56pm
12/7/2009 12:56pm
Does it matter which year was so fast?

It's much easier to go faster around a track on the new ones that have less peak hp but likely have more average hp over a usuable RPM band.

Ideally you want a bike that feels slow because it has a completely linear and smooth powerband. If it's making a lot of power while doing this, you will go around a track much faster.

Lots of bikes throughout history had narrow powerbands that excelled in a small region but even Pros have moved away from that sort of powerband.

As far as the guy w/ an '09 that wants to slow it down; the thing is already a pussycat "IF" the jetting is correct. Most of them have an all wrong needle jet that goes from too lean to too rich making them sort of jump right there in power. A JD needle jet can correct that problem usually.

The other thing is the PV spring is really misunderstood. Yes the stiff spring delays the PV opening which makes the bike slower up until that point, but then it hits and the jump to full power is more sudden making it hit even harder. So run the softest spring, correct the jetting, increase the flywheel weight. and hit the gym. You can also run the jetting a bit fat to make it hit softer.

If that doesn't work you probably need a 250F or something.

Kinetic1
Profile picture for user Kinetic1
Posts
2796
Joined
6/4/2009
Location
Gun Lake, MI, USA
Kinetic1 12/7/2009 2:06pm
12/7/2009 2:06pm
I put the soft spring in my uncles 300EXC for him and WOW!!! That thing really does run like a three stroke. What a tractor. I thought I remember that being the white spring but I could be wrong. I've been giving serious consideration to a new 300XC and modifying it for moto or a 250SX with the 300 top end.
Outsider
Profile picture for user Outsider
Posts
10628
Joined
1/29/2009
Location
Huntington Beach, CA, USA
Outsider 12/7/2009 2:25pm
12/7/2009 2:25pm
Kinetic1 wrote:
I put the soft spring in my uncles 300EXC for him and WOW!!! That thing really does run like a three stroke. What a tractor. I...
I put the soft spring in my uncles 300EXC for him and WOW!!! That thing really does run like a three stroke. What a tractor. I thought I remember that being the white spring but I could be wrong. I've been giving serious consideration to a new 300XC and modifying it for moto or a 250SX with the 300 top end.
I've been giving serious consideration to a new 300XC and modifying it for moto or a 250SX with the 300 top end.

Me too! Smile
DrSweden
Profile picture for user DrSweden
Posts
6761
Joined
8/30/2008
Location
Stockholm, SE
DrSweden 12/7/2009 2:42pm
12/7/2009 2:42pm
More than one mag had dynos showing 50 hp on the rear wheel, isnt like 5%-10% wasted between wheel and crank?
Outsider
Profile picture for user Outsider
Posts
10628
Joined
1/29/2009
Location
Huntington Beach, CA, USA
Outsider 12/7/2009 3:48pm
12/7/2009 3:48pm
So, what year(s) did the motor mellow out? Anyone?

I don't want a 55hp 2 stroke unless it has a 5lb flywheel weight!
Ing
Profile picture for user Ing
Posts
3654
Joined
8/16/2006
Location
Spring Hill, FL, USA
Ing 12/7/2009 4:34pm
12/7/2009 4:34pm
Outsider wrote:
So, what year(s) did the motor mellow out? Anyone?

I don't want a 55hp 2 stroke unless it has a 5lb flywheel weight!
04
fossil
Profile picture for user fossil
Posts
3
Joined
12/7/2009
Location
Boyd, WI, USA
fossil 12/7/2009 6:46pm
12/7/2009 6:46pm
fossil wrote:
What is the easiest way to tone down an 09 KTM 250SX. I'm a fossil who is trying to learn to ride this thing after being...
What is the easiest way to tone down an 09 KTM 250SX. I'm a fossil who is trying to learn to ride this thing after being on a yz250f for the past 5 years. Should I set the power valve late in the band, early, leave it alone, gear differently, different pipe?
Kinetic1, hope you're right. in that I've forgotten how to ride a two stroke. I should have included I have not been on a two stroke since 1977.
WhKnuckle
Profile picture for user WhKnuckle
Posts
7327
Joined
7/17/2007
Location
USA
WhKnuckle 12/7/2009 6:50pm
12/7/2009 6:50pm
fossil wrote:
What is the easiest way to tone down an 09 KTM 250SX. I'm a fossil who is trying to learn to ride this thing after being...
What is the easiest way to tone down an 09 KTM 250SX. I'm a fossil who is trying to learn to ride this thing after being on a yz250f for the past 5 years. Should I set the power valve late in the band, early, leave it alone, gear differently, different pipe?
fossil wrote:
Kinetic1, hope you're right. in that I've forgotten how to ride a two stroke. I should have included I have not been on a two stroke...
Kinetic1, hope you're right. in that I've forgotten how to ride a two stroke. I should have included I have not been on a two stroke since 1977.
Check out KTMTalk.com. Those orangebloods know everything about KTMs that humans can comprehend. They can tell you how many threads are on the front screw that holds the clutch slave cylinder to the case. They can tell you the exact torque spec of the bolts that hold on the front fender.

Seriously, those guys are hard core.

Pit Row

See All »

Post a reply to: question for the KTM 250sx Experts...