SECRETS OF BUILDING A MOTO-READY KTM 300XC TWO-STROKE RACER

KTMphil

Senior member
Joined
Jan 11, 2011
Location
Chiang Mai, Thailand
Bikes
2007 KTM 990 Adventure Suzuki DRZ 400
By Jody Weisel

The vast majority of my racing life has been spent on two-strokes, but I'm a realist. When the four-stroke revolution came along, I didn't feel a need to fight it. I have said many times that, if I weren't a motorcycle test rider, I would be racing a Yamaha YZ250 two-stroke. However, my lot in life is to race and test what's put before me, and, increasingly, since the four-stroke revolution began in 1998 and went full complement in 2006, the bikes I am assigned to race are four-strokes.


A SMOKER'S POWER-TO-WEIGHT RATIO IS UNBEATABLE—EXCEPT BY THOSE GENIUSES AT THE AMA


I'm not whining, nor am I anti-four-stroke; I just believe that the sport would be better off with cheaper-to-purchase, less-expensive-to-maintain, simpler-to-work-on, 20-pound-lighter and more-powerful-per-cubic-cc two-strokes than bulkier, heavier, costlier and more complicated four-strokes. As technically advanced as a modern four-stroke engine is, it's still Ford Model A-era when compared to a light and powerful two-stroke. A smoker's power-to-weight ratio is unbeatable—except by those geniuses at the AMA. You may not believe me, but I'm past worrying about what the masses think.


The only visible clue that MXA's project bike started life as a 2012 300XC cross-country bike is the 18-inch rear wheel, which we initially kept because it worked very well.


Thus, when I was assigned to run MXA's test program on the KTM 300XC cross-country bike, I considered myself lucky. (Actually, I make the test assignments at MXA, so luck really had nothing to do with it). I wanted to test the 300XC because I wanted to race it. I felt that a torquey 300cc two-stroke would be the perfect mix of power and thrust to race with 450 four-strokes. I wasn't worried about beating them, because I wasn't beating them on a 450 thumper. But I had to complete the test assignment before I could go whole hog.


The regimen for testing is fairly straightforward. First, the studio photography is shot, followed by the action photos, and then the dyno time. Only then do we start a series of test days with different riders to try to discover every nuance of the bike. As the test riders work their way through each phase, the project leader collates the input, makes the suggested changes and arranges to retest every alteration. Finally, we begin racing the bike to ensure that our setup and test data aren't pie in the sky. It is quite an exhaustive procedure, but fun at the same time.







More here:


http://motocrossactionmag.com/Main/News/INSIDE-SECRETS-OF-BUILDING-A-MOTOREADY-KTM-300XC-T-8778.aspx

 

LivinLOS

Senior Member
Joined
Feb 10, 2011
Bikes
Gas Gas 250 (Trials), YZ250 (enduro), DRZ440 (Supermoto) CBR900 Streetfighter (scary !!)
Motocross action tend to have good 2 stroke coverage without going down the total AMA approved 4 stroke only line.
 
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