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How to make KTM 300 keep up with the 450's

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So I rode my first 450 4 stroke yesterday [2005 RMZ 450]. The bottom end and mid range felt much stronger than my 14 300XC and the bike was a wheelie monster. I was really surprised as I thought my 300 2 stroke would be just as powerful.

 

So it makes me wonder. What kind of work would need to be done to a 300 2 stroke in order to match or beat the power of the 450? Not that my 300 needs any more power. It already has PLENTY for the woods. Just curious is all.

 

My bike is 100% factory stock and only has maybe 3hrs on it. I haven't played with the jetting or even the power valve springs yet.

 

 


please don't be biased just because this is a KTM 2 stroke section.

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Generally both bikes should be pretty well matched, your 300 has as much or a bit more hp and is lighter, if you run them side by side they should be pretty neck and neck, so I think you are just noticing the difference in power characteristics between a 2 stroke and a 4 stroke and maybe some gearing differences.  RMZ is also the full MX spec, so may compare better to a 300SX - some people put SX ignitions on their XC's to change the characteristics a bit, but if you just want to whack the throttle in any gear and wheelie, the 4 stroke will be better at that, if you want to whack the throttle go really fast and then wheelie uncontrollably  when the powerband hits, a 2 stroke is better at that - put the red spring in your powervalve and the 300 will throw you off the back in first gear when the powervavle opens!

 

It's just different, I think you are just as fast in reality!

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Red PV Spring

Re jet the carb with the NECJ suzuki needle out of a RM250

FMF fatty and shorty muffler

250sx cdi

Set the X to zero and shave the head to have a 1.3mm squish and then try her out should smoke pretty much anything you line up next to it.

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Not to bash another poster's opinion, but my '07 300 came to me with a JD needle and it sucked. The KTM jetting chart is pretty accurate and the bike runs MUCH better with their recommended needle, etc. than it did with the JD one. Also as has been said, red PV spring and head milling. I had an FMF pipe but I like the Pro Circuit pipe better. On mine I simply went to the thinnest base gasket available and shaved .035" from the head. It will decimate anything and will pull a gear taller out of a corner than it did before. Your bike already has lower transfer ports than the earlier 300s, (IIRC, it's about .5mm or .020) so your work should be confined to the head without efforts to lower the cylinder.

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Not to bash another poster's opinion, but my '07 300 came to me with a JD needle and it sucked. The KTM jetting chart is pretty accurate and the bike runs MUCH better with their recommended needle, etc. than it did with the JD one. Also as has been said, red PV spring and head milling. I had an FMF pipe but I like the Pro Circuit pipe better. On mine I simply went to the thinnest base gasket available and shaved .035" from the head. It will decimate anything and will pull a gear taller out of a corner than it did before. Your bike already has lower transfer ports than the earlier 300s, (IIRC, it's about .5mm or .020) so your work should be confined to the head without efforts to lower the cylinder.

You'd be one of very very few (the only one I've ever heard of) who thought the KTM needle was better than the JD. Are you sure there wasn't another change that you made that made the jetting better? Could it have been the wrong JD needle? I've used them with very good success in the past. 

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You'd be one of very very few (the only one I've ever heard of) who thought the KTM needle was better than the JD. Are you sure there wasn't another change that you made that made the jetting better? Could it have been the wrong JD needle? I've used them with very good success in the past.

The truth is I don't know exactly what needle it was. The previous owner told me it was a JD kit, but the needle had no markings. It was the only change I made at that time. I could tell there was something not quite right with the jetting, so I put in the recommended KTM needle and it works very, very well. I see no reason to go to JD when there are so many choices available already.

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The truth is I don't know exactly what needle it was. The previous owner told me it was a JD kit, but the needle had no markings. It was the only change I made at that time. I could tell there was something not quite right with the jetting, so I put in the recommended KTM needle and it works very, very well. I see no reason to go to JD when there are so many choices available already.

Most people go with the JD kit because it's so easy to get right, if you don't want to waste time dicking around and want to get to riding it's 95% plug and play. My buddy and I have the same bike, I run the JD kit and he jets off the chart. Now I know you may think I'm BS'ing here but this is the honest truth. My jetting seems to work over a much broader range than his, where we live it's pretty darn mild and I never mess with the jetting, he ends up changing his several times/year, and all the while he always talks about how well my bike runs. 

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Most people go with the JD kit because it's so easy to get right, if you don't want to waste time dicking around and want to get to riding it's 95% plug and play. My buddy and I have the same bike, I run the JD kit and he jets off the chart. Now I know you may think I'm BS'ing here but this is the honest truth. My jetting seems to work over a much broader range than his, where we live it's pretty darn mild and I never mess with the jetting, he ends up changing his several times/year, and all the while he always talks about how well my bike runs.

I have heard similar things about the JD kits. My experience just wasn't that way. I did try leaner and richer on the pilot and main just to see what would happen, different clip positions, etc. just to learn the bike's behavior since it was new to me. Since going to the KTM recommended needle, I have just left it alone. I has far better mid range and insane throttle response. Mileage is excellent too, I have gone 80 miles without ever using reserve. If somebody had the "correct" JD needle, I would try it, but I have a hard time believing that the bike could run any better than it does. I think the lowered cylinder and shaved head actually make it easier to jet. Jeff Slavens says the same thing. It was his "Mule" thing that inspired me to do what I did with the motor and it works wonders.

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I have heard similar things about the JD kits. My experience just wasn't that way. I did try leaner and richer on the pilot and main just to see what would happen, different clip positions, etc. just to learn the bike's behavior since it was new to me. Since going to the KTM recommended needle, I have just left it alone. I has far better mid range and insane throttle response. Mileage is excellent too, I have gone 80 miles without ever using reserve. If somebody had the "correct" JD needle, I would try it, but I have a hard time believing that the bike could run any better than it does. I think the lowered cylinder and shaved head actually make it easier to jet. Jeff Slavens says the same thing. It was his "Mule" thing that inspired me to do what I did with the motor and it works wonders.

Like I said, you're not the norm, probably 99% of people who mess with their jetting find a better needle than the KTM one, nobody runs those, but glad it's working for you. I think you had the wrong JD needle for sure because both the blue and the red were an improvement in my bike.

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Like I said, you're not the norm, probably 99% of people who mess with their jetting find a better needle than the KTM one, nobody runs those, but glad it's working for you. I think you had the wrong JD needle for sure because both the blue and the red were an improvement in my bike.

Don't take offense, but my opinion of the whole JD thing is that it's marketed to people who are either afraid to tune their own bike or they don't know how. I guess my 35 years of riding, racing and tuning has left me out of that group. I'm fairly certain that the engineers at KTM and those at Keihin have a pretty good idea what they're doing. To think that they would miss the mark so completely and that some guy in Weehawken has the magic cure in a box is really not logical. But as you said, I'm glad it's working for you.

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Don't take offense, but my opinion of the whole JD thing is that it's marketed to people who are either afraid to tune their own bike or they don't know how. I guess my 35 years of riding, racing and tuning has left me out of that group. I'm fairly certain that the engineers at KTM and those at Keihin have a pretty good idea what they're doing. To think that they would miss the mark so completely and that some guy in Weehawken has the magic cure in a box is really not logical. But as you said, I'm glad it's working for you.

I'm not taking any offense at all, its just a discussion. Now let me ask you a question, do you only run stock expansion chambers, oem silencers, reeds, pistons, etc? 

 

I agree that a lot of the oem parts are quality and that KTM does a good job, but as I've pointed out 99% of people have better results with a needle that is not the oem needle, even tuners who have more experience and better results than you do. Not knocking you, but pretending like your 35 years experience adds up to more than the real pro's (not shade tree guys like yourself)  is the most illogical thing either of us has said. Again, you don't even know if your needle really was a JD needle, could have been the seller was just telling you that hoping to make a sale. Back that up with the anecdotal evidence that just about everyone who tries a JD needle says its better and we've got even more reason to believe yours wasn't. Just keeping it logical you know  ;)

 

 

Edit: Did the seller tell you it had a brand new top end yet not have any reciepts? Something tells me he did.  ;)

Edited by Squid_Racer
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a few days back I put a sxs head and vf4 reeds on a 13 xc-w and jetted it- it was a change for the better the dealer jetting sucked  my jetting specs would be use less to you in newhampshire, rejet your bike before any complaining.

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The benefits to the JD kit are you have everything you need for every elevation/temp. combination. If you compare the JD chart and the KTM chart you will find that a JD set up covers a broader range of conditions compared to stock. I'm not saying the stock KTM jets are wrong, they actually are spot on but they also require more tuning to keep in the correct range.

As far as making the 300 hang with a 450 MX bike my honest opinion is it will but it requires you to ride it differently. I think the OP is referring to torque of the 450 of which a 2 stroke will never compare. The 300 makes its power by the means of rpm. A well tuned 300 and 450 have similar top HP numbers but if you look at dyno numbers of the two you will see they make their power in totally different rpm ranges/curves.

My 2013 300XC Setup:

JD Jet Kit

FMF fatty

FMF power core

250SX CDI

250SX Head

Yellow PV Spring

13/48 gearing

The bike is very fast, especially when it can find traction. Unfortunately most of the time in the desert traction is hard to come by.

Edited by hezzdown

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I'm not taking any offense at all, its just a discussion. Now let me ask you a question, do you only run stock expansion chambers, oem silencers, reeds, pistons, etc? 

 

I agree that a lot of the oem parts are quality and that KTM does a good job, but as I've pointed out 99% of people have better results with a needle that is not the oem needle, even tuners who have more experience and better results than you do. Not knocking you, but pretending like your 35 years experience adds up to more than the real pro's (not shade tree guys like yourself)  is the most illogical thing either of us has said. Again, you don't even know if your needle really was a JD needle, could have been the seller was just telling you that hoping to make a sale. Back that up with the anecdotal evidence that just about everyone who tries a JD needle says its better and we've got even more reason to believe yours wasn't. Just keeping it logical you know  ;)

 

 

Edit: Did the seller tell you it had a brand new top end yet not have any reciepts? Something tells me he did.  ;)

No, PO was obviously not super intelligent as the bike was setup very poorly. It ran sluggishly, and the suspension was off-the-charts awful. I imagine he hated it as it was. His loss, my gain. But, your "evidence" that "everybody" likes the JD needles better just happens to coincide with my opinion that almost "everybody" in this electronic age is incapable of tuning a carb, be it a Rochester, Weber, Mikuni or Keihin, and they cannot tell the difference in symptoms between too rich and too lean. (I can almost hear it; What? Isn't there an app for that?) I ride between 5000 and 7000 feet. My address is 2227 N 825 E Lehi, UT 84043. Send me the one you're not using and I will try it out. Either way, I'll send it back along with a Domino's pizza coupon for the effort.

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No, PO was obviously not super intelligent as the bike was setup very poorly. It ran sluggishly, and the suspension was off-the-charts awful. I imagine he hated it as it was. His loss, my gain. But, your "evidence" that "everybody" likes the JD needles better just happens to coincide with my opinion that almost "everybody" in this electronic age is incapable of tuning a carb, be it a Rochester, Weber, Mikuni or Keihin, and they cannot tell the difference in symptoms between too rich and too lean. (I can almost hear it; What? Isn't there an app for that?) I ride between 5000 and 7000 feet. My address is 2227 N 825 E Lehi, UT 84043. Send me the one you're not using and I will try it out. Either way, I'll send it back along with a Domino's pizza coupon for the effort.

Well I'll give you this "evidence" I can tune a carb modestly well, certainly not the best at it but I can jet just off of feel from riding the bike and making changes and back it up with plug chops. My buddy has the exact same bike 2001 KTM 200. He has a pile of needles (a few of which I gave him that I had tried) and he is a real solid mechanic, in fact much better than me I'd say, he did it professionally for quite some time. He uses the KTM Jetting chart and he seems to love messing with jetting. Yet after about a year of him messing with stock needles, needles that others say to try like the honda needle (I think maybe its a Zuk needle) and the other KTM needles he can never seem to make his bike run better than mine. He too thinks the $70 for the JD kit is a lot of money but I think if it weren't for his hard headed stubborn nature (and the fact that I told him to just JD jet it and be done) he too would be running the JD kit. 

 

I'm tempted to send you my other needle but I do sometimes swap them between summer and winter, and besides I dont' think the needle for yoru bike would be the same as mine. What carb does your bike have? I run a 38 and just picked up a 39 I'm goign to try, yet another reason to keep both needles handy. 

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The benefits to the JD kit are you have everything you need for every elevation/temp. combination. If you compare the JD chart and the KTM chart you will find that a JD set up covers a broader range of conditions compared to stock. I'm not saying the stock KTM jets are wrong, they actually are spot on but they also require more tuning to keep in the correct range.

As far as making the 300 hang with a 450 MX bike my honest opinion is it will but it requires you to ride it differently. I think the OP is referring to torque of the 450 of which a 2 stroke will never compare. The 300 makes its power by the means of rpm. A well tuned 300 and 450 have similar top HP numbers but if you look at dyno numbers of the two you will see they make their power in totally different rpm range.

Agreed. Four-strokes make their power in a different way. It's like comparing a Cummins to a Hemi. The charm of a 300 with some mods is that it can be short shifted and still pull very cleanly, yet it has a wicked top end for when you want the hit. I used to ride CR500s, so my riding style is somewhat tainted by that, I like huge hit and I manage it with the throttle.

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Lehiguy, you never answered the question regarding if you run other after market parts on the motor? Or do you only apply this thinking to jetting?

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Well I'll give you this "evidence" I can tune a carb modestly well, certainly not the best at it but I can jet just off of feel from riding the bike and making changes and back it up with plug chops. My buddy has the exact same bike 2001 KTM 200. He has a pile of needles (a few of which I gave him that I had tried) and he is a real solid mechanic, in fact much better than me I'd say, he did it professionally for quite some time. He uses the KTM Jetting chart and he seems to love messing with jetting. Yet after about a year of him messing with stock needles, needles that others say to try like the honda needle (I think maybe its a Zuk needle) and the other KTM needles he can never seem to make his bike run better than mine. He too thinks the $70 for the JD kit is a lot of money but I think if it weren't for his hard headed stubborn nature (and the fact that I told him to just JD jet it and be done) he too would be running the JD kit. 

 

I'm tempted to send you my other needle but I do sometimes swap them between summer and winter, and besides I dont' think the needle for yoru bike would be the same as mine. What carb does your bike have? I run a 38 and just picked up a 39 I'm goign to try, yet another reason to keep both needles handy.

If you can tune a carb you are part of a vanishing breed. Mine has the 36mm. The older (and apparently newer ones too) have the 38. I have been tempted to try a bigger one, but the thing runs so incredibly well, that at this point I think I would be foolish to mess with it. Oddly, I had a Power Core II silencer and that made the bike ping no matter what jetting I ran. (admittedly, I shaved the head right to the limit for my altitude) It is super happy with the stock silencer, so that's what I run. I think I may have stumbled onto some perfect balance of things as they are, so for the last year I just fill the tank and ride which is what we should be able to do.

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