MXA TEAM TESTED: MILLENNIUM TECHNOLOGIES KTM 270 BIG-BORE KIT

October 31, 2013
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WHAT IS IT?
Millennium Technologies is making a 270cc kit for the 2013 KTM 250SXF four-stroke. This is a straightforward bore and re-plate project that doesn’t cost an arm and a leg.

WHAT’S IT COST? $246.70 (bore/re-plate cylinder), $212.93 (Vertex 81mm piston), $60.84 (Cometic gasket kit).

CONTACT? www.mt-llc.com or (920) 893-5595.

WHAT STANDS OUT? Here’s a list of things that stand out with the Millennium Technologies KTM 270SXF big-bore kit.

(1) Problem. The MXA wrecking crew usually calls Cylinder Works to get a completely new big-bore cylinder, but with the 2013 KTM 250SXF, that wasn’t possible. The development time to cast a big-bore cylinder that would fit on the new 2013 KTM 250SXF engine was about 10 months, which meant that Cylinder Works’ kit won’t be available until later this fall. We were in luck, though, because Millennium Technologies was able to bore the stock, 78mm cylinder out to 81mm, re-plate it with a nickel silicon carbide coating, and fit it with a brand-new, 81mm Vertex piston. The final displacement was 269.5mm.

(2) The job. All you have to do is pull your 250SXF engine apart and send the cylinder to Millennium Technologies. They will do the rest, which includes sending it back to you with the piston, rings, circlips  and gasket kit in the package. Turnaround is seven days at Millennium, so plan to be without your cylinder for at least two weeks.

(3) Price. Not including shipping, you can turn your 250cc KTM into a 269.5cc KTM for $520. You couldn’t buy an aftermarket exhaust pipe for the price of building a big-bore Millennium 2013 KTM 270SXF.

(4) Performance. This was the best $520 we have ever spent. We gained horsepower all along the dyno curve?from as little as one more pony at 6000 rpm to five more horses at 11,000 rpm?and the added torque helped the rather linear 250SXF powerband become more kinetic. Instead of laying down and waiting for the rpm to build, we could short-shift, rev it to the moon or slam through the gearbox. It had enough power to pull a taller gear when it counted. It hit harder and didn’t lose any rev on top. Sweet.

WHAT’S THE SQUAWK? No complaints. We didn’t even have to make any mapping changes.  


If you aren’t bound by the rule book or ethics, Millennium Technologies’ 270SXF big-bore kit is the best way to get competitive power at a wallet-friendly price. We liked this engine a lot better than the stocker.

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