MXA TEAM TESTED: KTM FACTORY SERVICE 350SXF TOP-HALF MOD

WHAT IS IT? KTM Factory Service is an engine modification program that is run through the KTM racing department. KTM customers can send their engines to KTM to have them tuned by factory technicians to the same specifications normally reserved for the factory team.

WHAT’S IT COST? Prices vary with engine type and size, but our KTM 350SXF top-half mod retailed for $3000?plus $899.94 for the titanium KTM/FMF Factory 4.1 exhaust with MegaBomb head pipe.

CONTACT? Your local KTM dealer.

WHAT STANDS OUT? Here’s a list of things that stand out with the KTM Factory Service engine mods.

(1) Performance. Before we delve into what exactly constitutes a “top-half mod,” let’s talk about what the KTM work did for our stock 2011 KTM 350SXF. First and foremost, most MXA test riders don’t like the stock KTM 350SXF powerband. They tend to think of it as two distinctly different powerbands that are poorly mated together. The low-to-mid powerband is torquey, but slow, while the mid-and-up powerband is revvy and reaches its peak horsepower at 12,300 rpm. This bad brew means that the engine isn’t fast enough to be ridden like a 450, but makes its peak too late to be used effectively as a mid-size four-stroke. If we had our druthers, every MXA test rider would prefer a single powerband with the peak horsepower moved down to a more manageable rpm level and enhanced by more thrust off the bottom. Surprise! That is exactly what the “Factory Service” mods did. They brought the peak horsepower number down from 12,300 rpm to 10,200 rpm, while increasing horsepower at every step along the curve.

(2) Dyno/track. Horsepower went up at 8000 rpm from 42.20 horsepower to 43.98 (1.78 horsepower more). At 10,000 rpm, the horsepower was up by 2.29 horse-power (from 46.57 horsepower to 48.86). Those are healthy gains on the dyno, but what was most noticeable on the track was that instead of taking its normal, leisurely stroll through the powerband, the Factory Service engine barked in the middle and filled in the sluggish gap that hurts the stock engine. It became one distinct and more focused powerband (and even though it still revved to 13,000 rpm, you didn’t have to go there to get max power).

(3) Mods. For the horsepower gains, we expected KTM’s Factory Service technicians to have replaced every part in the top-end of the 350SXF (and the price tag was healthy enough to support that supposition). Wrong! The top-half mod included no actual parts, but instead consisted of porting and flow testing the cylinder head, decking the cylinder to raise the compression from 13.5:1 to 14:1, retiming the stock cams (by moving the cam sprocket), changing the EFI mapping (to make it leaner on top), and adding a private-labeled FMF Factory 4.1 exhaust system. Once KTM has buttoned your engine up, they run it on the race team dyno to ensure that it is producing peak horsepower.

(4) Transaction. Your local KTM dealer handles the complete transaction. You bring him your engine and he ships it to KTM’s North American headquarters.

WHAT’S THE SQUAWK? Price (we hate to think how much a full-top mod costs if a top-half mod is $3000).

You have to look at yourself in the mirror and ask how much 2.29 horsepower is worth. For MXA, it changed the ill-conceived stock 350SXF powerband into one unified engine. We liked it.