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Thread: Tuning 300 e/xc Power

  1. #1
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    Tuning 300 e/xc Power

    Hey Folks-

    I've got an 01 300 e/xc, which I really like. However, after riding a friends 02 250 e/xc, I realize that the surplus of low end power is almost detrimental to my riding- it lets me get away with too much slop (which slows me down) and it gets tiring to manage the power. On the 250, I was immediately riding faster, because you have no option but to keep it on the pipe and charging, where the 300 will just torque over things.

    Before I sell the 300 and buy a 250, any thoughts on how to give my bike more top end and less low end? Jetting, powervalve adjustment, etc?

    I've always jetted by the book, and the bike has a procircuit pipe. Otherwise stock.

    All suggestions are appreciated.

    Thanks,

    Ned
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  2. #2
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    I've never played with the 300's power valves, since I own a 200.

    However, my brother has used the power valve adjustment quite a bit on his 300. I don't know which way adjusts for low end vs. top end, but I know it is a very responsive adjustment.

    Turning it in (again, not sure of the direction) let's the motor kick you in the butt when it goes on the pipe. Turning it out softens the hit and adds some low end.

    Either way, the 300 has huge power, so you might just have too much engine for what you are comfortable with.

    I don't know if the manual explains how to adjust the power valve, but try turning the adjustment screw (a little brass screw on the lower right side of the engine I believe) 1/2 turn at a time to see how it reacts.
    Mark McDonnell
    ECEA B-200
    '01 KTM 200 MXC, '03 Yamaha YZF600R, '97 Honda Shadow Spirit 1100
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  3. #3
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    I only know from what i´ve read. check thread "300exc", they said the power on the 300 can be adjusted a lot to your liking, with power valve, and mostly jetting, also with flywheel weights. So i would read those posts, play around with the tunning, before u go and sell the 300.
    However, i also think by what u´ve said that the 250 might like u more, cause u can gas it without fear, while on the 300 watch out throtle open full.

    03 - 250exc
    03 250e 2s
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    Heck, guys, it's only 50cc bigger than a 250. It's not like a 380, or a Husky 360, let alone a real big-bore two-stroke like a CR500. The 300 can be very manageable in the woods. Try a single-taper needle like a CEK or CEJ. Then if that's not enough, try tightening the tension on the power valve spring by tightening the screw, and the PV will kick in later, taming the hit. Another technique is just to ride the thing a gear high. It will pull it, and you'll torque over anything in your way without jerking your arms out of the sockets. One more thing; the best pipe for smooth power is the stocker. The PC pipe emphasizes the mid-top power, which produces a big hit. Good luck. If it's really too much, you'll like the 250.
    "Again with the squeaky shoes."

    '05 Gas Gas 300DE
    '02 KTM 400SX/EXC
    '02 KTM 400 SX
    '75 Yamaha TY175
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  5. #5
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    Thanks for the responses... just wanted to clarify what I was after a bit.

    The ultimate power of the machine is not too much, in fact, I'd like a bit more for hillclimbs and so on.

    In riding the 250, it seemed to pull a bit longer on top, which made long steep climbs easier, as I could hold a gear for longer, and when I kicked it down one, I was back in the meat of the power.

    As for torquing over things, yes, it's amazingly good at that. Unfortunately, I don't think this is the fastest way to ride... it might be possible to go as fast, but it doesn't focus my concentration the same way that keeping the bike on the pipe does.

    I'll give a straight taper needle a try. How will changing needle affect what jet size I need to use? As I mentioned in the previous post, I've always jetted by the book, and since I live at altitude and ride everywhere from sea level to 14k feet, I'm rejetting pretty much every ride... so having a system for jetting is important to me.

    Cheers,

    Ned
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  6. #6
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    i have an '01 300, a new leftover, & i'm trying to get a broader spread of power while keeping the torque. my complaint was that the bike had a vicious hit in the middle, but no top. i wanted to keep the bottom, smooth out the middle, add to the top for less shifting & b/c i don't like the tractor-style powerband so many guys tune their 300s to have (came off a tricked-out 200 so was used to that). i've ridden numerous 250s--a few of my own + others, including an '03--& they are nice, but they require a downshift when they fall off the pipe, whereas the 300 will just keep on chugging. i want that bottom with smoother mid & more top.

    so far i have switched to the tassinari reed & a ddk needle. i just put on a pc pipe, but haven't tried it yet. the reed block added response from top to bottom, a nice change. the needle (remember to bump the main a couple sizes) smoothed out the monster hit & made the bike much easier to ride fast, esp. when tired.

    i'm looking for the pipe to add to the mid & top; we'll see. the needle makes a huge difference & removes the incentive to do what it sounds like you are doing, chugging around below the hit in the powerband. there are tons of threads on this board & others about these needles; the guru of this stuff is a nice, helpful guy named james dean. but if you do a search on all of the ktm boards, you will see miles of posts about it. good luck!
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    Lawman, let me offer some rebuttal testimony, if there is no objection. Two things: if you can ride a KTM 300 on the pipe all the time, you're a better man than I am. Whew! Second, you might consider that riding on the pipe may feel faster to you when in fact you might be going slower. Smoother is usually better in the woods. The defense rests. Res ipsa loquitur.
    "Again with the squeaky shoes."

    '05 Gas Gas 300DE
    '02 KTM 400SX/EXC
    '02 KTM 400 SX
    '75 Yamaha TY175
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  8. #8
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    On my 2001 KTM 300 EXC, I got a noticable boost by adding the V-Force reed, needle replacement and jetting. Went from 38 hp to 46 hp on the Dyno.

    I replaced the stock pipe with a FMF Rev Pipe (I think they sell narly for low end enhancement, fatty for mid-range and a rev pipe for top end) This combined with the right silencer will change the dynamics of the powerband.

    In addition to the suggestions regarding powervalve I am sure you could go with a lighter flywheel and make your 300 feel like a 250 on steroids.
    Moto-Monkey
    meyer2503@home.com
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    hey jmd, i'm just too old & lazy to shift! no, really, call me crazy, i just don't like the tractor-type power, i like to ride it on the pipe more.

    i got to try the pc pipe & s/a sunday, in the snow & sleet, until i sank my bike in a mudhole up to my belly button (was i cold? sure, until 2 guys & i had to hump the dead bike up a small mountain--glad they were there!). it is now all to pieces to be cleaned & dried out (some fun, you bet!). but i can give this report on the pipe: it hits the spot. with the jetting, reeds & pipe, the bike has a ton of smooth, tractable power in the bottom & mid, then a smooth transition onto the pipe, then much more top end. it no longer requires a shift in the midrange, it actually has very good top end power. i have the power valve adjusted to open fairly early as well. it is much more useable for me, just what i was hoping for when i switched to the 300 from a tricked-out 200. i like it!

    further lawman sayeth not.
    Last edited by lawman; 02-12-2003 at 10:06 AM.
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  10. #10
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    I think there are a lot of good suggestions here, but I go along with what Mark said about the power valve. I think you should be able to get what your looking for with adjustments there.

    From there the jetting and then triming the flywheel. But, keep in mind, these mods will tend to make it come on much harder. It could become a real hand full.

    One thing that wasn't suggested was gearing a little taller, like a tooth or two smaller on the rear. That will make the grunt on the bottom less effective at torquing you around and require you to run more up on the pipe. The down side is it will slow response some. The up side is it will tend to make the gears longer. So you could either try it now or save it for later, if it gets too beastly.
    MOTORHEAD

    You don't stop riding because you get old, you get old because you stop riding.
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  11. #11
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    mtrhead: good suggestions as well. i've run the pv screw in & out numerous times; mainly what i want is smooth power--i.e. to lose the nasty hit it had stock--& to broaden the powerband to reduce the frequency of shifting. i'm considering shaving the flywheel--2 buddies have done this on their '03 250 exc's--but since you can't put it back once you've shaved it off, i'm holding off on that. i tried 13/52 gearing per someone's suggestion, but that was too low, esp. after i switched out the needle. now have 13/51, it's still a little low. i'll be putting on a 50 after i reassemble the bike; that will be just a tad lower than stock. that should smooth it out & reduce the shifts even more,w/o requiring me to go to 1st every time the woods get really tight (common here in the deep south). i bought the bike cheap as a new leftover with a some concern about the weight & power, i really liked my tricked-out 200, but i like the big boy (after the mods) even better than i thought i would. a 450 exc would have cost me about $3k more & so far, i'm glad i saved the $.
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  12. #12
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    dose anyone know what is the best jetting on a 03 300 exc
    dino colaianni
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