Dellorto VHST Racing 26 BD Carburettor - starter lever

Carburettor Dellorto VHST Racing 26 BD of 26 mm with lever-operated starter.

The VHST Racing 26 increases the mixture flow, allowing it to feed engines that demand a much higher flow rate. This becomes especially important when the exhaust enters resonance and the cylinder starts to fill and empty at very high speed: that is precisely when you need the intake to be able to keep up.

What really changes when fitting a 26 mm carburettor? In a setup that needs it, the engine gains greater fuelling capacity in the mid and high range, can maintain cylinder filling better at high RPM, and is no longer held back by the restriction caused by a carburettor that is too small. The result can be an engine with more power, better over-rev, and a greater ability to make the most of the cylinder and exhaust potential.

But diameter is not everything. The carburettor works thanks to the Venturi effect: as the air accelerates through the narrow section of the duct, the pressure drops and the vacuum is created that draws the fuel up from the carburetion circuit. The better this flow is controlled, the better the atomisation of the petrol and the formation of the air-fuel mixture.

If you fit a 26 mm carburettor but keep an original reed valve box, you simply move the bottleneck a few centimetres further on. For a more complete setup, we recommend combining it with a reed valve box and a manifold.

A reed valve box with a greater effective flow area and petals suited to the engine speed range allows the mixture to enter the crankcase with less restriction. This is especially helpful when the engine revs high, since the reeds have to open and close thousands of times per minute in step with the crankcase pulses.

The result of correctly combining carburettor + manifold + reed valve box is a much more coherent intake system: better flow, fewer restrictions, and fuelling capable of keeping up with the cylinder throughout the entire RPM climb.

Technical characteristics

• Manufacturer: Dellorto.
• Model: VHST Racing 26 BD.
• Diameter: 26 mm.
• Air intake: smooth 49 mm connection.
• Engine connection: 36 mm rubber sleeve.
• Starter: manual, lever-operated.

Standard settings

• Slide: 55.
• Needle: D38.
• Atomiser: 272HH.
• Main jet: 104.
• Pilot jet: 40S.
• Starter jet: 60.
• Float valve: 270.
• Floats: 15760.5 - 3.6 g.