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Am I the only one who hates the red PV spring?

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I keep reading about the great results from the red PV spring on the 250/300's but my 2000 runs terribly with the red spring or PV screw turned out flush with the housing. It gets blubbery and rich feeling. I'm tempted to try to jet it out but it runs pretty well with the stock yellow spring and the screw turned about six turns in so I hate to mess with it too much.

I checked the PV wile running and it operates correctly. The adjuster changes the RPM at which it starts moving. I had the same results with the bike as a 250 and as the 300 that it is now. Z set to factory specs.

Overall it runs good but I'm still searching for a bit of throttle to rear wheel connectivity that's missing from time to time. Under a load there's a touch of a flat spot or bog in the middle of the PRM range that I can't jet out. Just bought a 36mm carb hoping it will help with this.

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It's not the spring it's your jetting!!!!!! What are you running for jetting? What premix? Something is not right. The red spring makes those old motors haul butt. And with the red spring you would turn the adjuster in. It's that much of a difference. Sounds like your jetting is rich. And a 36mm carb is only going to give you maybe more bottom and it will need to be jetted as well. Did you get any jetting specs? Get a JD jet kit for the 38 and jet the thing. If you need more help JD has great customer service. And try a V-Force or Rad Valve reed cage assy as well. Also a big improvement over the stock reed cage. It's all in the jetting believe me.

Edited by ktmfred300

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It's not the spring it's your jetting!!!!!! What are you running for jetting? What premix? Something is not right. The red spring makes those old motors haul butt. And with the red spring you would turn the adjuster in. It's that much of a difference. Sounds like your jetting is rich. And a 36mm carb is only going to give you maybe more bottom and it will need to be jetted as well. Did you get any jetting specs? Get a JD jet kit for the 38 and jet the thing. If you need more help JD has great customer service. And try a V-Force or Rad Valve reed cage assy as well. Also a big improvement over the stock reed cage. It's all in the jetting believe me.

I have chased jetting quite a bit. I've tried a bunch of different needles including DJ's, slides, pilots and mains and think I have a pretty good feel for the process. I've settled on a 40 pilot, CEL needle second clip from the top, #6 slide and 170 main for 4500-6000 feet elevation. The richer #6 slide seems odd to me but the #7 felt flat no matter what needle or clip position I used.

FYI - it's a 2000 250exc with a 02 300 crank, cylinder and head cut by cycleplayground. Just converted it from 250 to 300 a few weeks ago. Also has a 07 250 SX CDI wired up with dual map ignition. I thought about advancing the ignition a touch - that seemed to work well as a 250 but I set it to spec with the 300 conversion.

Current jetting offers acceptable power and fuel mileage wise but I feel like there's more somewhere. Looking for big off idle torque and a linear throttle connected to the rear wheel feel from there. I don't like much of a hit.

I has to stop messing with the jetting/PV and just enjoy the thing for a few rides and it's actually pretty good. I went through the same process on my 200 and the work was well worth it - that motor seems to read my mind now.

This powervalve thing baffles me though. I've thought about adjusting the PV out and rejetting to that setting but I'm not ready to start that process over quite yet. Might wait for the 36mm carb to show up first since I'll be starting over with that anyways.

Thanks for the input.

Edited by rip2622
forgot to include elevation

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I've run all 3 springs and never changed jetting. I don't see how changing at what rpm the power valve opens has anything to do with jetting. I think you have a jetting issue. The red spring has plenty of linear power delivery, too much for me in tight single track or slick conditions, I ran it for a couple of years with adjustment out flush. I now run yellow with adjustment a couple turns in.

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I'm gonna adjust the PV out and jet today. I'm thinking that perhaps my current PV setting is masking a jetting issue. I'll update if I discover anything new.

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i use the red spring on my 300 xc-w but went with the green spring on my 250sx. the 300 i dont notice to much change in the springs but like the red alittel more since it seems to already be more trackable. the 250 sx i noticed a huge difference. made it alot easier for me to ride.

Also check out feb 2012 issue of MXA magazine. they have a opne page article on the ktm springs and adjuster. pretty good basics. They said they usually go with the yellow spring in the article but whenever i read their magazine tests on 2-stroke

ktms they always say they like red for mx. they also test the new 300xc for mx in that issue.

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The older motors have different porting so it works well on them. The SX 250 is a much more aggreesive motor not needing the red spring. It sounds to me that you are rich on your jetting. Lean out the needle and see what happens.

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I tried the red spring on my (updated) 01 300exc today. It was pretty exciting ...the first half hour i did not care for it that much. As i got used to it,became easier to ride. The bike lifted the front (unprovoked) more times in 2 hours then it has in 2 months. In twisty s/t that isn't really a good thing. Adding 1 click of compression on the shock helped. My guess is the average 300 rider would really like this spring.

More specific to me,sea level,great air (47 deg.46 r/h 30.20 baro) 155lb. This spring is probably not ideal for my bike setup. Late,300 36mm carb,/air box,stock pipe (torque city) and rekluse pro. I will try the red spring again in the heat of summer.

I have all the springs (red,yellow,green) from my other 300. I have only used the standard yellow spring on the 01 for the last 3 years.

I am off tomorrow,temps are forecast to be the same. I will try the green spring. My guess is it will be quite a tractor....and more to my liking.

1-1-10213.jpg

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I keep reading about the great results from the red PV spring on the 250/300's but my 2000 runs terribly with the red spring or PV screw turned out flush with the housing. It gets blubbery and rich feeling. I'm tempted to try to jet it out but it runs pretty well with the stock yellow spring and the screw turned about six turns in so I hate to mess with it too much.

I checked the PV wile running and it operates correctly. The adjuster changes the RPM at which it starts moving. I had the same results with the bike as a 250 and as the 300 that it is now. Z set to factory specs.

Overall it runs good but I'm still searching for a bit of throttle to rear wheel connectivity that's missing from time to time. Under a load there's a touch of a flat spot or bog in the middle of the PRM range that I can't jet out. Just bought a 36mm carb hoping it will help with this.

Rip -

As other have pointed out, it sounds like your complaint is related to jetting.

Nevertheless, I'm not a fan of the "red PV spring and adjuster flush with the cases" that some people advocate. In all but the tackiest dirt this setting just promotes wheelspin. Remember, the goal is maxium acceleration, not necessarily the most power and especially not the most abrupt power. For the optimal balance of traction and power, the adjuster needs to be tuned to match soil conditions. If you don't use a PowerDial, experiment with a screwdriver...but don't just "set it and forget it."

Edited by Adammoto

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Also has a 07 250 SX CDI wired up with dual map ignition. I thought about advancing the ignition a touch - that seemed to work well as a 250 but I set it to spec with the 300 conversion.

I thought we couldnt use the dual map ignition on the older bikes? Obviously you found a way, please share the specifics! :smirk:

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