Xc vs Sx (Gearing!)

[schwany31]

Hello...

Yet another ktm 2 stroke thread...strictly gearing

First off, I want to say my current setup.

2012 yz250f chassis, yz300 engine

Fully built
Tom Morgan ported, vp110, yzX trans (closer 3rd gear)

Mated to aro 120...stock gearing. Set up has been awesome out west and in the Midwest (u.p)

It's time to go KTM....

Idc about the stator, bigger tank and electric start, i can add to a sx when needed.

I want opinions on sx vs xc gearing in the snow world only...

Is the sx to close?

Thanks for the advise!

Also i have read through many different threads and they almost all seem to go with, well the XC has a big tank and e start so go with that...

Thanks!



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[wwillf01]

Man.... having ridden both the yz is pretty hard to beat in the snow unless your going go full sx, port, pipe ignition... I ended up ordering a Panthera stator and estart..... that being said I like the sx trans... for trees... either way I think you will be playing with gearing to get it just right. That being said what ever is the best deal then adjust with gearing .

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[schwany31]

Thanks! I'm at the point where I need to stick a little money into my bike before winter and im so sick of dealing the a Frankenstein bike..having a hard time deciding what I am going to do....fyi it would be a 11-2015 ktm

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[wwillf01]

So if you don't go sx it is harder to get the revs because of the exhaust port height from what I understand... so then the catch is you don't have electric start which sucks... but those years the starter had a harder time in the cold weather but were good once warmed up. Also the sx rake works way better for snowbiking in my opinion..... keep in mind I am in Utah so what works for me might not be for you.

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[byeatts]

KTM SX and XC share the same tranny, Its perfect in the snow

 

[schwany31]

I have read a few things about the exhaust port, so I agree with you on that.

I believe you can add e start by just swapping out that case half. Correct me if I'm wrong

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[schwany31]

KTM SX and XC share the same tranny, Its perfect in the snow

Isn't the xc a 6 speed..

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[wwillf01]

You would need to reference the years.. it changed along the way but I thought the sx was a 5 speed then

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[schwany31]

You would need to reference the years.. it changed along the way but I thought the sx was a 5 speed then

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Yes sx is a 5 speed and xc is a 6, so different trans

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[wwillf01]

For me the 6 speed had a large gap to 3rd ... that was always the issue you try to gear out.

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[byeatts]

For me the 6 speed had a large gap to 3rd ... that was always the issue you try to gear out.

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the XC 450 and SX 450 share same 5 speed gearbox, the XC 300 has close ratio 6 speed, The xcw all have the 6 speed with a gap between 2nd and 3rd.

 

[Saundet]

My 13 SX has electric start and I believe 13 was the first year of fuel injection, something to keep in mind.
tranny ratio is great, we do a lot of tree riding, deep snow.

 

[eric82930]

Whoa there. You guys can't mix gearing info between 2 and 4 strokes. The 2 stroke sx and xc have NEVER been the same and 2010 xc got 6th but you CAN'T add 6th to a 2 stroke sx.

You can add estart to the sx up to 2016 without splitting cases. After that cases and crank are different.

The sx ratios are really close and work great if you don't gear too low on the track. If you can't run a clutch then the 6 speed xc would be better because you could gear the track for lower 1st and still have the top speed in 6th.

The port heights on sx and xc are same only diff is head compression and cdi.

Only the 300s have the lower port timing

 

[schwany31]

Whoa there. You guys can't mix gearing info between 2 and 4 strokes. The 2 stroke sx and xc have NEVER been the same and 2010 xc got 6th but you CAN'T add 6th to a 2 stroke sx.

You can add estart to the sx up to 2016 without splitting cases. After that cases and crank are different.

The sx ratios are really close and work great if you don't gear too low on the track. If you can't run a clutch then the 6 speed xc would be better because you could gear the track for lower 1st and still have the top speed in 6th.

The port heights on sx and xc are same only diff is head compression and cdi.

Only the 300s have the lower port timing

Thanks for chiming in the the 4 stroke talk....
I am worried about the gap from 2nd to 3rd on the XC...It seems on my YZ and other bikes i have ridden im primarily in 2nd gear and some climbs 3rd when i can pull it. Having a lower 3rd gear on my YZ really helped. The 3rd to 4th gap was only OK if i was on the trail.

Do we have anyone out there who has ridden both? My riding with consist of 1 trip to WY and multiple trips in the U.P

Thanks

 

[eric82930]

So sorry I have to ask to clarify was your yz300 a 2 stroke or a typo? If it was a 2 then did it get ported for mid range or top end? Mid range porting seems to need closer ratios. Top end motors (like stock ktm 250s) don't seem to care as much about gaps in gears. They might not have as much low end but on deep days it's irrelevant because no matter what you ride you need to be on the power peak not lugging around. All you need is a motor that has some over rev past the power peak to get you to the next gear. This is why the stock 250s are always leading the pack ahead of the stock 300s.
If you find a deal on an 250 xc don't hesitate at all. Sx heads are cheap and if by chance someone put a gnarly on it, swap it for a pc platinum.

I have even run xcw gears on a top end ported 300sx and it pulled the gaps in the gears better than my close ratio 380 because the 380 had no over Rev.

 

[schwany31]

So sorry I have to ask to clarify was your yz300 a 2 stroke or a typo? If it was a 2 then did it get ported for mid range or top end? Mid range porting seems to need closer ratios. Top end motors (like stock ktm 250s) don't seem to care as much about gaps in gears. They might not have as much low end but on deep days it's irrelevant because no matter what you ride you need to be on the power peak not lugging around. All you need is a motor that has some over rev past the power peak to get you to the next gear. This is why the stock 250s are always leading the pack ahead of the stock 300s.
If you find a deal on an 250 xc don't hesitate at all. Sx heads are cheap and if by chance someone put a gnarly on it, swap it for a pc platinum.

I have even run xcw gears on a top end ported 300sx and it pulled the gaps in the gears better than my close ratio 380 because the 380 had no over Rev.

My yz300 is a 2 stroke. Balanced crank and porting primary for mid to top with more in top, also running a lectron 38.

If i buy a Xc, ill do the sx ignition and for sure run a different head or get the stock one cut.

At this point i think i XC may be a little better doing the few SX engine mods to it right away,

 

[byeatts]

Thanks for chiming in the the 4 stroke talk....
I am worried about the gap from 2nd to 3rd on the XC...It seems on my YZ and other bikes i have ridden im primarily in 2nd gear and some climbs 3rd when i can pull it. Having a lower 3rd gear on my YZ really helped. The 3rd to 4th gap was only OK if i was on the trail.

Do we have anyone out there who has ridden both? My riding with consist of 1 trip to WY and multiple trips in the U.P

Thanks

there is No Gap on any gear spread on the 2 stroke XC models .Only the XCW and six days have the gap.

 

[schwany31]

there is No Gap on any gear spread on the 2 stroke XC models .Only the XCW and six days have the gap.

But a bigger gap than the sx models. I am not interested in the xcw, although the low first would be nice in the off road world here and there.

 

[byeatts]

But a bigger gap than the sx models. I am not interested in the xcw, although the low first would be nice in the off road world here and there.

The XC is perfect tight ratio gear spread along with a 6th gear.

 

[schwany31]

Someone mentioned that the sx handles better, is this due to the triple clamps offset or is the frame stem at a different angle ?