KTM 2 stroke Auxiliary Springs | Power Valve Springs | Which one do I like best?

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Red spring, Yellow Spring, Green Spring? What does all this mean? In today’s video, I’m covering the basics of what you need to know about these Auxiliary springs (also referred to as power valve springs).

Me personally, I prefer to use the Red spring since it lets the power valve open sooner than the other options. Yellow is okay. The green is not my cup of tea.

Keep in mind that this is for the carbureted bikes only. KTM doesn’t want us playing with the springs on the TPI bikes (fuel injected). The TPI bikes I have ridden ran really, really good anyway and I didn’t feel the need to change anything anyway.

Derek Wylie, Joe & Alex Van Orsdol, Paul Appleton, Jim Bass, Garrett Wastlund, Matt, Chris Able, David Adams, Blair Butler, Brian Falcon, Seth Green, Terence Seymour, Sean Williams, Ryan Woodley, Flo Motorsports, Nate Winget, Steven Brady, Travis Winston, Steve Yurko, Chad Cooper, Mitchell Forest, Mark Fleischman, Dion Jaramillo, Ken Paulino, Paul Warner

[brucejones]

I switched out to the red spring after riding my 300 for 15 years. I should have done it sooner. I was used to 2T mx bikes and the red spring gives it the same kind of snap. It's easier for me to ride, I can stay much of the time in 3rd in the woods I ride - the transition from lugging to power is quick and that's perfect for me. PS I'm 65

[t_orcutt]

Green spring my fave for woods and gnarley single track riding (300 xc). All the power is still there when you want it, the tamer delivery keeps the bike from trying to shoot out from underneath you when you’re popping over the gnarly stuff!

[shawnbrummett]

It would be cool to see a bike on the dyno with all three springs installed

[rogerhupp]

Kyle, thank you for taking the time to explain the characteristics of the springs. After reading the manual, I just expected the red spring to be the most erratic. But how you explained it, I now think it’s the spring I could benefit from the most.

[Hillcapper]

I’ve had 2 300’s, a 2004 MXC and currently 2013 XCW. I messed with spring and adjustment on both quite a bit. What I found with both was the factory setting is really best. Green spring is nice if you never get in the power band much, but when it does finally hit it’s always a surprise. I ran red for a couple of years (I typically ride hilly single track with some fast open sections) and found that traction suffered since it was a little harder to stay out of the big power down low. Yellow with a couple turns in let’s me stay out of the big power when I want to without the big hit when it does come in. I know right when it’s coming on though so it’s very useable.

[shawnjohnston]

Hi Kyle, love the vids and can’t wait for some 300 tpi videos and reviews. With the power valve I done some research and chatted with Chris Birch in depth and this is what I have found out... all 3 springs open up at about 5650 rpm but the differences are at what rpm the power valve is full open. The green Spring starts to open at 5650 and is fully open at 8100 and the red spring opens at 5650 starts and is fully open at 7300. Yellow spring somewhere in the middle. What does this mean? Essentially the red spring is fully open the quickest giving you that “snap” or “hit” harder where the green spring makes the power valve open more slowly and therefore less “hit”. For riding...guys that ride the track and open country probably will prefer the yellow and red spring and guys the ride the slow, gnarly technical stuff will be better off with the green spring (less hit, less wheel spin, more traction). Like Birchy said if you want the hit and you are running the green spring it’s just a stab of the clutch to get the rpms up and the power valve is fully open. I think one of your other viewers commented that Jarvis runs the green spring and I wouldn’t be surprised. Birch says all the top guys will run the green spring and screw turned in!
All true but now tpi bikes so not an issue. Ps. Chris did play with the springs on his 250 tpi, ran like crap and put back to stock!

Enjoy the vids! Cheers!

[jbraz]

I've got a 2018 husky tx300 it came with the stock yellow spring and the worst jetting I've ever experienced. After finally getting the jetting dialed in I've put the Green Spring in from the yellow and it made a world of difference. I like tight technical Terrain

[NirHason]

I think your explanation is not correct Kyle :)
The AUX spring controls how fast the PV opens not when it starts to open.
The Pre-load spring controls on when (which RPM) the PV starts to open.

[mikelyons]

Very good informative video, love your Channel. I also love your shelves with rear tires. I'm making some this week, also going to drill holes throughout the bottom bead and put small S hooks on so I can hang wrenches from. Very cool. 3rd gear pinned forever.✊

[AndrewBoundy]

...

1. There are two springs. The outer spring controls when the PV opens (at what RPM). This is controlled by the screw. The inner (coloured) spring controls how fast the PV opens when it does and is adjustable by spring type (colour/weight). A faster (lighter) inner coloured spring (red) will allow the PV to open more quickly and perhaps deliver a noticeable "jolt" whereas a stronger spring will make it slower and more linear. Power is the same, speed in which the power is delivered, differs. You also have a throttle that does that.
2. KTM tune the PV to 'begin' opening at a certain RPM - this is based on the harmonics of the exhaust expansion chamber as well as it's length, curves, back pressure and all sorts of other factors costing $-millions to develop. I seem to remember around 6K-rpm as being the number. Ask yourself - do you know more than KTM about fluid dynamics? If not, leave it at factory specs. If you're changing the breathing of the bike (intake/exh), maybe a PV tweak on a dyno. might find you something - maybe?
3. For trail riding, changing your PV settings (screw) won't make you faster - it'll probably depower the bike somewhere in the RPM range as it's now not to factory optimum specs. Any gains you get top-end may be felt at the bottom - power can be transferred but not created on a bike (or indeed, in physics).

4. Expert riders (not you or me because we're watching this) may set-up the bike differently depending on the specifics of the race/terrain. MX/SX/Enduro/SM may differ depending on the track. Open desert guys may need all top-end and little down low and technical guys may keep the PV closed longer to gain more low-end tq - whatever. Similarly, expert riders may like the feeling of a different speed spring - fair enough.
If you're losing a podium by 1 second, sure, have your team look into it.

The moral - honestly, like most of this stuff, leave it alone and/or make sure it's to factory specs - spend your time on the bike and your money on riding lessons from pros.

Peace!

[nvader]

I've got to look into what spring is in my '08 300xc. The bike is out of control powerful for me. I had an '01 300Exc that was a pure pleasure to ride, with awesome power, but my '08 is just uncontrollable right now. Easily the most powerful bike I've ever ridden. I'm tired of replacing rear fenders. lol.

[Scottstunts]

I run the green spring in my 17 TE 300, more linear power band and I’ve found it’s better for nearly every situation.

[backyardmoto]

So I'm never removing the red spring,
Exactly what I felt the 300 should feel from the jump!

[rzyam]

2012 TE 300, yellow spring, adjuster flush with case. 2013 250 XC-W, yellow spring, adjuster flush with case. Both run very well for Colorado Mountains and technical stuff.

[JacquesDigital]

My 2013 ktm 300 got it with red spring it was turned all the way in and was just scary just touched the throttle and the valve opened have green spring and is smooth

[adambatchelder]

Yep in 250s red spring pre load backed out to flush. Along with thin base gaskets and high compression head and the exhaust flange welded and relived inside of course. Makes for a smooth strong power delivery.

[robmanzanares]

maybe this contributes to the content: Auxiliary springs: red 1.1mm wire, 54837072000 blue 1.2mm wire, 54637072500 yellow 1.3mm wire, 54637072300 green 1.5mm wire, 54837072100 (9 coils)

[dukenevr]

Thanks for the video.

It pays to check the adjustment on a new bike, even though they come with the yellow spring. My new '18 300XC came with the Power Valve adjusting screw turned all the way in. Did not know that and took it for a spin around the neighborhood and was like WTF, this thing has no snap! Then I checked it, wound it out 6 turns (8 turns total from all the way in to all the way out) and it was much better. I generally run the power valve at 2 turns in from fully out.

I also usually run the red spring on my 300s too as I live in Denver and ride at elevation. Also ran a Gnarly pipe too on my '13 TE 300. It was a little aggressive, even here in thin air land! I like it. Going with the yellow spring on the new bike to start as I am running an S3 head and Lectron on it, which will enhance the off idle snap, and looking to rev the far smoother counterbalanced bike more. I set my '13 up to be a bottom end beast to avoid having to rev it as much as possible, as it numbed my hands.

Running the red spring, Lectron and the S3 head on the new bike might be a little much - baby steps, starting with the stock yellow one - LOL

[oscarkelly]

Could never get my te300 running how I wanted. Red spring in, wind out the preload a bit and it was a new bike

[Sparky]

It's funny you'd post this today. I was watching your video from a few years ago on this last night. I'm pretty sure I'm going with the devil spring dialed back a bit.