2006 Husqvarna TC250

2006 Husqvarna TC250 – A Major Engine and Chassis Step Forward

The 2006 Husqvarna TC250 was a significant update rather than a routine model-year refresh. Husqvarna retained the basic 249.5cc DOHC four-stroke architecture introduced earlier in the decade, but extensively reworked the cylinder head, valve train, intake and exhaust systems while also making important changes to the motocross chassis and suspension. The result was a substantially more serious attempt to compete with the rapidly improving Japanese 250 four-strokes.

The engine still used its short-stroke 76.0 x 55.0 mm dimensions, but almost everything affecting breathing was revised. Intake valve diameter increased from 29 mm to 30.5 mm and exhaust valves grew from 24 mm to 25 mm. Husqvarna redesigned the camshaft profiles, intake and exhaust ports and combustion chamber, introducing a larger squish area intended to improve combustion efficiency. Compression was a high 12.9:1, appropriate for a race-focused engine designed to operate at high rpm.

Fuel was supplied by a 37 mm Keihin FCR flat-slide carburettor with accelerator pump and throttle-position sensing. Correct accelerator-pump timing, pilot circuit condition and jetting are particularly important on these early high-performance four-strokes, where poor carburetion can make starting difficult and produce hesitation when the throttle is opened quickly. Owners rebuilding a worn original unit can compare replacement carburettor options when assessing suitable alternatives.

Husqvarna also altered the transmission specification. The TC250 retained its five-speed motocross gearbox, but second gear was made taller for 2006 to improve the spacing of ratios on the track. The starting system changed as well. The electric starter fitted to earlier motocross versions disappeared, leaving a lighter kick-start-only arrangement with an automatic decompressor. Removing the electric-start hardware was part of Husqvarna's effort to reduce the weight of the dedicated TC competition model.

Suspension was another major area of development. The TC250 received a 45 mm Marzocchi upside-down closed-cartridge fork, while the rear of the motocross range adopted an Öhlins shock. The front fork offered around 300 mm of travel and used a factory oil level of 100 mm with the fork compressed and spring removed. Owners servicing the original suspension can use the MXOwners fork oil reference when checking setup information.

The braking package used a 260 mm front disc and 240 mm rear disc, while the normal motocross wheel combination remained 21 inches at the front and 19 inches at the rear. The TC250 ran an 80/100-21 front tyre and 100/90-19 rear, sizes that can be cross-checked against current replacements using the MXOwners tyre size guide.

Maintenance remains especially important on a surviving 2006 TC250. The engine uses dry-sump lubrication with two oil pumps and a cartridge filter, and the engine, gearbox and primary drive share the same 10W-60 lubricant. Factory cold valve clearances are 0.10-0.15 mm on the intake side and 0.15-0.20 mm on the exhaust. Frequent oil and filter changes, clean air filtration and regular cam-chain and valve-clearance checks are essential on a competition engine designed to spend much of its life at high rpm.

Historically, the 2006 TC250 represents an important stage in Husqvarna's attempt to establish itself in the modern 250F motocross class. It was not an entirely new motorcycle, but the larger valves, redesigned ports and combustion chamber, revised cam timing, lighter kick-start configuration, closed-cartridge Marzocchi fork and Öhlins rear suspension amounted to a substantial redesign of the existing platform. For today's owner, it remains a distinctive Italian alternative from the intense early years of four-stroke 250 motocross development.