Likely operator error. Most dynos don't work well at all below 3k rpm ( no idea why). A dyno operator is SUPPOSED to roll on the throttle quickly, but smoothly, when it's time to up the revs. But you see a lot of operators just whack it to WOT and wait till redline. Considering the nature of CV crabs, I could see that creating this issue here. Simply conjecture, ofc.Kind of odd that all 3 of those engines have that little dip-spike near 3800-4100rpm.
shinyribs,What that graph fails to show is the most important area to have torque, which is low rpm. I have ridden my riding buddy's XR650L a lot and it will blow my KLR in to the weeds at lower speeds. Hell, my little XR400 will, too. All of Honda's XR engine are extremely torquey engines, but they run out of steam very quickly. You can make them rev to high rpms, but the bike doesn't really build any speed for it. They love to be short-shifted. Stab a XR650L while rolling along in 1st or 2nd gear and they will stand up on power alone. The KLR needs the clutch dropped to do the same.
That said, the KLR will still beat an XR650L in a flat out dag race ( in my experiences with my buddy), but I credit that to the KLR's ability to rev well... never thought I'd type those words...lol. I know most guys post about keeping revs down while cruising, but I was pleasantly surprised the first time I ripped through the gears on my KLR , going to redline in every gear. It really pulls great! Glorious sounds, too. I fully believe that graph. A KLR will eat a XRL on topend, hands down.
This reminds me of something I've thought about asking several times, but figured I'd get laughed at. lol
Back in my drag racing days we used to play with valve lash to get an engine to produce power where/ how we needed it. Loosening the lash on the exhaust valves ( effectively reducing the duration) will always make more torque across the rpm band. Sometimes the dyno would show huge imrovements. Like, 30, 40 or even 50 ft/lb worth. It depended on the cam profile and other variables, but it was a consistent way to ekk out some launching power without sacrificing too much top end, run-for-the-stripe hp. Has anyone every tried playing with valve lash on the KLR to see if they could find some more bottom end grunt?
Double Over-Head Camshafts.
We are NOT advancing the Intake numbers in anyway! The Intake remains 100% totally stock and standard.
Yes, the airbox mod definitely does far more at higher rpm's than it does at lower ones but it is a much greater restriction than the muffler is. Pulling the airbox door (even for testing) is a bad idea and people that have tested it have come to the conclusion that at higher speeds the airflow past the door and/or the riders leg can actually create a low pressure area that DECREASES air flow. Another thought to consider is that your "butt dyno" works OK at lower speeds but not so well at higher speeds. As long as you've pulled your snorkle, you've got marginally/almost acceptable airflow for a stock KLR.I haven't opened up my airbox. If the bike can run 7k-8k rpm now ( and it does), then I cant see how its restricting any power in the sub 2k rpm range. But I could be wrong. A free flowing muffler has been the #1 thing I've done to improve off idle grunt on my KLR. World of difference. For a quick and dirty test I once ran around a few miles with the air box door off. I saw no difference, so I pooped the door back on and decided against drilling any extra holes.
shiny,Thanks, Dave. I can't honestly say if my bike has a screen or not. I hope it does,,,, lol
I've considered drilling the extra holes, but I ride in so much dust and dirt that I hate opening them up. My bike parks outside and I worry about critters getting in the airbox. I put some mesh over where the snorkel should be. Probably paranoia, but it is what it is.......
My engine spends the vast majority of it's time running 3500 rpm or less. Oh, and my test w/out the airbox door was just around the farm. As suspected, no difference for just trail riding.
I pondered on the MC thing some more,,,,,,,,,, but I wouldn't know how to contemplate the lack of scavenging, if any. Odd that there isn't more feedback on this topic.
Back to the idea of playing with lash to create more low end torque, I'm not sure how much lash would be a good idea anyway.-------
Surprised there are no aftermarket cams for the KLR along the lines of "towing and RV" cams. Maybe there is and I'm just not aware.