2012 KLX250S after DIY mods DYNO CHART
 

Results :
19.1 horsepower rear wheel , estimated 22.92 horsepower at crank.
14.56 torque at rear wheel , estimated 17.47 at crank.

What you need to know :
Elevation was 490 ft above sea level.
Temperature was 100 F - The SAE correction with a smoothing of 5 was used .. so this is corrected horsepower to 77 F and 29.23 Hg
Pull was made in 4th gear - chosen by the tuner as the better choice out of several passes made in other gears. Tire is original equipment at 26 psi.
Tuner calculated and wrote the estimated power at the crank based on a 20% powertrain loss.
Air/Fuel ratio was perfect for everyday use but tuner said more power would be made if I richened it up. It was 14 to 1 with a spike that went up to 14.6 between 4750 and 6000 rpm.

This is what I got after performing the DIY mods on this forum:
2012 KLX250S with 320 miles - Marcelino cam mod , Dynojet stage 2 as per instructions , airbox lid removed , DG slip-on , port match header flange to exhaust port.

Wow.. That's worse than I thought it was. In modified condition it couldn't crack 20 hp.... I knew when riding it off the dealers lot that the klx wasn't a powerhouse. Gotta say that the big bore kit still is the number 1 on the list of mods for that anemic engine.

Well, I love the big bore kits. The hours searching here for dyno reports on the 351cc kit seems to show about 26 hp at the crank. I made about 23 on a very hot day with a lean A/F mixture. The torque figures also compare in a similar way. I spent a total of $ 206 on my mods - slip-on and Dynojet kit - to get these results.

Iirc the big bore kit was $550 ish delivered, and I needed a $36 valve cover gasket since the original one shrank. Figure $600 total, $390 for an extra 3-4 hp... Hmm doing the math never makes it look like a good deal

Yeah,,, And on top of that $550 you still need to spend the $200 on a slip-on and re-jet kit to get the 26 hp out of the 351 !!!!
Bill Blues' web site lists the 351 with "stock" carb and exhaust to have the same power I now have !!!!

I have no idea how to correct the lean spike in the A/F that occurs, starting at 4750 and ending at 6000 rpm. The peak "leanness" occurs at 5700 rpm then drops sharply back to 14 to 1 by 6000 .

The horsepower and torque curves suffer a "dip" as well during this lean spike. HELP!!!

ithink there are guys with charts showing 25-26hp at the wheels BB kit and stock exhaust and carb. around 30 with full exhaust. that's quite a bit more than your 19.


but all dynos are subjective and comparing charts is essentially worth less. still BB kits show consistently more gain than any other mod.

Wildcard you are wrong. Those charts you refer to are with additional mods on top of the 351 kit, and they top out at 26 hp and may be at the crank. Bills' web site lists the dyno chart with stock carb and exhaust, and I have read on this forum that his chart(s) are at the crank. It makes about the same as OUR mods do on a stock bike. With head porting, cams, Bills exhaust system, and his pumper carb, you get about 30 hp and a wallet that is about $2400 lighter. Add in larger valves with the associated valve seat work for about 34 hp and a total cost of about $3000.

Klxster, how has the 'feel' of the bike changed? I'm planning on ordering the same parts as you today, hopefully next weekend I can get everything swapped over. I've read dyno charts and mod threads for the last few days since buying my bike, I'm thinking that either your dyno read low or others read high. Maybe not, I don't know.

You said your A/F ratio was a tad lean for more power, but fine for daily riding, at dynojet's stage 2 instructions. Would you recommend going a little bit richer? Maybe another notch on the needle or something?

Also, what is your elevation? That could affect your jetting and power level. I'm at 1000' here, and generally stay between 750' and 2000'.


Thanks a lot.

Just when I had my last bike figured out I had to go and get another one. I'm loving this little guy so far, but a bit more low end hit would be much appreciated. I'm coming off an XR650R and switching to this as a dual sport/adventure bike/backroad bomber/trail bike/touring bike. Big bikes are cool and all, but so far I've ridden every trail that my XRR took me and then some, plus have gotten there less tired and feeling ready for more rather than worn out.

Jules, I will edit the my original post with elevation figures.. I'm Dallas Tx so we are talking about 500 - 700 ft . Dyno runs and charts are a conundrum. Drawing conclusions and making comparisons to others' charts is engaging in pure speculation based on opinion. For instance - your opinion is that my numbers are low. I absolutely disagree. On a 100 degree day, at 500ft ASL, running a 14 to 14.6 A/F, using a knobby dual-sport tire, I made 19.1 SAE corrected hp at the rear wheel on that Dyno.
In the real world on a cool day with the A/F closer to 12.8, It'll make way more.

But opinions are like pie holes - everyones' got at least one.

The bike "feels" totally different from a stock KLX. It is actually fun now. Click my login and look at my posts for more.