post-mod dyno runs

[Jim & Shannon Morehead]

Hi All, I guess everyone who's interested has looked at the A13 dyno runs I posted to the files area of the KLR650 e-groups site. The runs are self explanatory, but I thought some folks might be interested in more details so here goes. I ordered and installed a Dyno-Jet kit, a K&N filter, and an IDS-2 Quite exhaust system. I removed the carb. to make things a little easier to access and chose to go with the "Stage-2" main jet marked 150. I put the needle clip on groove #4 and put the two washers above the clip per the Dyno-Jet instructions. I also drilled the slide with the Dyno-Jet supplied drill bit. While the carb. was off, I popped the plug out of the mixture screw as Dyno-Jet suggests. I turned the screw all the way in and cut off the excess material below the threads to allow easier access when the carb. is back on the bike. Then I set the screw to the 3-1/2 turns recommended in the kit. I also modified my airbox as illustrated in Motor Mark's web site including removing the screen between the filter and carb. I gotta say that cutting the top out of the airbox was really simple, but getting the all of the screen bits out was not easy. I kept having horrible mental pics of little screen bits going through the carb, head, etc. I was really surprised that the screen mesh is so tight. That thing has to be very restrictive. Thanks for the site and pics Mark. The K&N installation was very simple, but I used the stock screw instead of the screw supplied with the kit. I installed the IDS-2 Quiet and all 12 discs without any trouble (no leaks at that point), but I just couldn't resist the urge to fire the little beast up without the muffler. Wow, what a wonderful sound, but I suppose we all have to be civilized and relatively quite. Post-mods, the bike ran great and had a lot more power from a "seat of the pants" perspective. Then it was back to the dyno. As you will note from the dyno-runs, even though the low and mid-range numbers were better, the first post-mod run (jetrun.001) actually showed LESS peak horsepower than stock. Needless to say, I was shocked and disappointed. The guys at M/C International were nice enough to let me experiment with the number of Supertrapp discs several times and re-test. Anyone in the Fayetteville, AR area should stop in and say hello to them. Six discs made things worse, but 9 discs improved the curves throughout the range, so we settled on that number. Overall, these mods netted an improvement of about 5% peak horsepower and 12% peak torque. I was hoping for 42-45 peak horsepower, but it just didn't happen. What can I say? The bike is much more tractable now and the low to mid-range grunt is dramatically improved. I can hit the redline in all 5 gears now and overall performance is definitely enhanced. Maybe it's my riding style, but my bike never got the great fuel mileage that some other listers report. I averaged about 48 mpg before the mods. and have been averaging about 38 mpg afterwards. The sound level of the IDS-2 Quiet is quite pleasant to my ears. Even non-bikers in my area tell me that the bike sounds good and is not objectionably loud. At least I can hear the engine run with my helmet on now. I did encounter one performance problem. The engine would die occasionally when I slowed quickly and pulled the clutch in to stop. It didn't die very often, but it was annoying. I decided to call Dyno-Jet and ask them about the problem. I also asked them about the minimal improvement in peak horsepower. The first person I spoke with at Dyno-Jet seemed more interested in avoiding responsibility for an unhappy customer than offering constructive comments. He actually said that the jet kits were not intended to improve horsepower, but were only intended to improve rideability!! I called back a day or two later and talked with a very helpful guy. He listened to my comments and offered a suggestion to cure the intermittent dying problem, but couldn't offer any tips to make more power. I made a small screwdriver out of a bolt and set the mixture screw at about 2-1/2 turns and the problem seems to have gone away. BTW, the guy that developed the KLR kit at Dyno-Jet said that the "airbox mods" he did for the Stage-2 kit tests consisted of removing the cover. Even though the results were less that expected, was the work and money expended worthwhile? YOU BET IT WAS!! I've run the bike about 1000 miles after the mods and have done a couple of other things lately that seem to help, but I haven't been back to the dyno or fully evaluated them yet. I'll let you all know what I find out. I hope everyone finds this info. and the dyno run pics interesting and informative. I also hope you long time listers will forgive me for boring you with info. that is no doubt old news to you. Let me know if anyone has any questions or comments. Jim