So, I bought a 2007 KLX250s this summer with about 7,200 miles on it. It has the K&N Air Filter, the two brothers exhaust, stock head pipe, snorkel removed but lid still on, and it has the dynojet kit with the 132 jet (I believe, this is based on looking in the dynojet kit and seeing that all the other jets are in there still with the exception of the 132 - i haven't actually taken the carb apart to confirm this). While the bike runs great, I rode my cousins 2006 KLX250s that he also bought this summer (and apparently had less than 400 miles on it when he bought it) which is completely stock, and while it feels as though you're going faster with my bike since it's so much louder with the two brothers exhaust on it, in reality I am not so sure that my bike is any faster or more powerful than his (when I ride mine vs his, I get to a good speed where it seems like i'm going pretty good, and look down and on the same uphill section I am going the same speed on both bikes, and his bike wheelies just as easy, if not easier, than mine does). Also, I know I get WAY worse mileage then he does with the setup on my bike (we went for a 100 mile ride, and I was getting about 65 mpg, while he was getting around 80 mpg or better). Anyone know why it wouldn't seem as though my bike is making more power than his is, or what the easiest way to test this is?

As for the low end power and wheelie-ability, I am thinking of doing the 13T sprocket up front and a 45T sprocket in the back. I know this is going to lower my top speed, but honestly 70mph on my bike is about all I want to do anyway, and I figure I would still be able to hit close to this even with the 13T-45T sprocket setup. Anyone have any thoughts on this?

 

Do you hve any dyno numbers? Witout them all power is just subjective stuff you tell us

 

132 jet may be too rich for your bike.

 

gearingcommander.com for comparing gear setups and checking theoretical speed potential.

If you're thinking 13/45 is really what you want, consider going 14/48. The larger front sprocket is easier on your chain. Then, you also have room to throw on 13 or 15 when you want a change. I ran a 49 for a while and am using a 51 now. You're probably going to need a longer chain with the larger rear sprocket.

What's the elevation where you ride?

Can you do roll-on acceleration tests of the bikes side-by-side. Say sixth gear, 45 mph side by side, and roll the throttles to WOT and see what happens.

65 mpg isn't bad.

 

No Dyno Numbers, and I know the 128 jet is what Dynojet recommends, however that jet is still in the kit that I got from the previous owner, so i am guessing the 132 is in it.

And I am planning on doing more dirt road/class 4 roads/trails through the woods, so I think the 13T front sprocket would be better for me. According to the gearing website (thanks for that link) I would still be able to do 72mph at 7800 rpms with the 13T / 45T setup, which isn't that bad (The amount of times i'll be going that fast will be few and far between, so not a big concern). With the 13T / 48T setup, 7800 rpms drops my speed to 67, which may be a little low, so I think either a 13T / 45T setup, or possible 13T / 43T setup might work for me.

Normally I am riding around 500ft to maybe 2,500 ft max elevation (typically though probably more like 500ft to 1,500ft).

And ya, I need to do that roll on test side by side with my cousin and his bike, see what happens. I have pulled away from him going up some hills before, but it's hard to say how true that is as I had no idea what gear and rpms he had.

And 65mpg was me following my father who didn't go over 45 on the main road and 35 on the dirt road, normally when I ride (which, true, isn't that hard either), but i'm around 50-55 mpg. Not great for a little 250cc.

Thanks for the responses! Appreciate it!

 

I know this may sound strange but....are you both close in weight physically?? 20 or more pounds can make a difference.

Are the rear tires the same size?

And I didn't see if you had that Cam Mod done. If not, that jetting will be way to rich I think.

 

I'm starting to sound like a broken record - Oh well...

Do the MCM ( Marcelino Cam Mod ) , insure that the carb is set up Stage 2 but with #132 and needle clip one notch lower on the needle than stage 2, pull the lid off the airbox, (take care that the float level is correct, an all air/fuel circuits are clean and functional.) and you'll have right at 20hp at your elevation - your AFR will still be a little lean but it's the best we can do with the DJ kit. When your closer to 1500ft, you'll be about correct with the AFR - there could be a bog every once in a while when you crack the throttle to wide open, if it bothers you, put the needle clip back to stage 2. - your AFR will then spike as high as 15:1 and your TRQ curve ( enhanced with the MCM ) will suffer a loss, up to about 1 lbft.

You will be making way more HP/TRQ than a stock KLX - Stock HP is about 16.5 based on the only complete DynoJet chart I know of. ( http://kustom-kraft.com/files/KLX250...rt_6_22_11.pdf )


Do it up as above, Dyno test it (as I did) , post your charts here (also as I did)...