Shadetree, what air filter are you running? Did you keep the air box lid and snorkel or are you running without them? I would think running without the airbox lid would make a big difference. I haven't put on my 340 kit yet because I'm still waiting for Bill Blue to send me my carb, but your results are very encouraging.Your jetting specs will help me a bunch in getting the carb dialed in early - thank you! BTW, why did you shorten the accelerator pump rod?

Frankly, I don't give a rodent's rectum how my KLX will compare with any other bike. My point in doing all of this is to have fun doing the mods and seeing how they makemy bike better andmore enjoyable. I like working on itas much as I like riding it. Am I spending foolish money? Probably, but so long as I'm getting enjoyment from it, so what.

 

Very true. My bike showed only 22.something HP on the first dyno run and then I rejetted the carb and switched to a non-knobbie 50/50 tire and it bumped up to almost 27 HP. I attribute most of that to the tire. So if you were running a knobbie, I can see you blowing past 30 HP if you switch. I used the Kenda 761 50/50 tire. If I ever dyno my KTM, I'll be using that tire on it as well.

 

Yea I'd say he's a lucky man

 

+10000000000000000

IG, seriously, you are a tool.

 

I know from experience, being on both sides of this fence with previously owning a similarly mod'd KLX and now owning a KTM 450 EXC "ready to race" bike, that the KLX331 + 35mm FCR + aftermarket exhaust and a few other mods, is the real deal. It's not a toy, it could be seriously competitive, IMHO, against 250 four stroke performance bikes.

Yes, the KTM 450 has noticably more power, but it's a 450 not a 331 so that is to be expected. However, the KLX331 is not blown away by any stretch. The big bored and pumpered KLX has that similar SNAP when you crack the throttle open and plenty of get up and go. The difference primarily seems to be in magnitude and that on the KTM you really feel it strong and this may be magnified by the stiff suspension on the KTM whereas with the KLX the softer suspension seems to absorb some of that hard edge. So the KLX makes for a far more comfortable and smoother ride overall.

So I wouldn't dismiss the KLX simply because of its humble beginnings. Larry Roeseler rode these bikes to much fame and glory for team green, and yes I'm sure the KLX's he rode probably had many $K worth of mods but the point remains the modified version can be a contender if you choose to build one.

I'm not saying you should keep your KLX and mod it up, ultimately you may never be happy always wondering what if, so please don't consider this as a recommendation for any particular course of action. I'm just saying that having direct experience on both an extensively mod'd KLX as well as a well respected "race ready" European enduro, the KLX shouldn't be dismissed so lightly.

 

There’s no need to apologize for being honest, Iowaguy, unless perhaps, honesty is out of character for you. In that case, claiming to be honest would be, well, dishonest, wouldn’t it? And then which scenario do you apologize for? I won’t play “Yes I did.” “No you didn’t” with you. As for your indecision as to what bike to buy, I don’t care. I’m not sure what I said to spark such a response from you anyway.

The rest of this post is addressed to those who don’t waste their time trying to be offensive.

I am using a Unifilter with No Toil oil. I don’t know how good it is relative to the others. I’ve seen claims of better flow and a test where it let too much water through. I suppose it could do both.

Brian, your bike had a nice, long, flat torque curve according to the dyno chart. It also made almost as many horses and kept them nearer to redline. My bike fell off after 8,000 rpm. I had upgraded cams and a bit of headwork too. This makes me wonder if the larger bore on your carburetor had something to do with keeping the power going longer. I hope I can get that dyno chart soon for you to see what I’m talking about. I think the porting and cams might yield quite a bit more power still, if the bike had a larger carb, but the question always comes up about what would happen to low and midrange power. The Husky makes tons of power, but uses RPM to process the air and fuel flows so it can.

The bottom line is that for me, this bike is 100% more rideable than when it was stock and I own it for much less than I would have paid for a known quantity like the KTM or Husky. I am by no means saying that I think it is a better bike. I rode several miles of desert on a 525 EXC and a BMW HP2 in January and I loved them both. Wish I could afford either one, but I can’t. The “Best bike” argument could go on forever, and to what end? I have had the pleasure of building the engine with my own hands and seeing the results in rideability and on the dyno. I’m happy with the power it makes now, although I was also hoping to see it go over the 30 mark just because it sounds good. I used a huge, Kenda Budds Creek knobby on the run. I wish I’d have been able to swap it for something smoother, but it didn’t work out. Maybe another time. Meanwhile, I enjoy getting to compare good, factual information with like minded folks. It saves on R&D and like many of you, I’ve made a few good friends along the way.

One more note of interest on tuning. I suppose I was lucky, but I got the second best power run with the jetting I had in the bike when I went in. 140 main, 40 pilot, second clip, yada-yada. After jetting between 135 and 145, including half sizes between, I finally gave up and went back to the 140. Then I shortened the accelerator pump plunger according to Bill Blue’s suggestion and two things happened. One, a small lean spike at tip-in throttle went away. Two, I picked up almost a full horsepower. Bill had suggested that that might happen because the shorter plunger rod allows the pump plunger to hold more fuel and to spray for a wider range of throttle position. I can’t wait for the new Clarke fuel tank!

I know, long post, but I don’t post all that often. I had to catch up.

Bill

 

Shadetree Are you running with the backfire screen still installed? What air box mods do you have? If I were you I would go down to the local motorcycle tire shop and try to find a 18" street bike tire and then get a dyno run, you will definitly see over 30hp. I also wonder about the size of the 34mm carb on 300 and 331 bikes. If you read on planet klx they recommend the tm33 for the 250 bikes but tell you that you should be running a 36mm on the 300. My opinion is also that the tm33(tm34) is to small for a 331cc bike especialy when you have head work and cams. And one last thing, the 125 two stroke might be making more power but have a race with one with a couple of laps around the local police department and see who wins the 2 smoke or the klx.