Bigbore 100cc Cylinder kit, HQ Racing Crankshaft and C4 bearings Yamaha DT LC/D VOCA Racing

Voca Racing kit consisting of a 100cc Bigbore cylinder, HQ crankshaft, and bearings , designed for Yamaha DT LC/D. This set offers the perfect combination of performance, durability, and reliability for 100cc BigBore-type builds.

The Voca BigBore 100cc cylinder is made of aluminum with a chrome/nickel coating and features 5 transfer ports and a bridged exhaust port. It is supplied with a 53.95 mm single-ring Vertex piston. The cylinder head is not included; it is recommended to install the VCR-RD11DT.54 with a recommended squish of 0.8 mm.

The Voca HQ Racing 43mm crankshaft incorporates an 85mm connecting rod and is manufactured from high-quality materials, counterbalanced with aluminum and bronze inserts to optimize rotation and increase precompression without the need to machine the crankcase. It is designed to reach up to 16,000 RPM and support 54 mm pistons.

Crankshaft features

• Stroke: 43 mm
• Connecting rod: 85 mm with 12x17x16 mm bearing
• Crankshaft webs: 77 mm for maximum precompression
• Upper counterweight in aluminum and lower in bronze
• Closed design to increase precompression in the crankcase
• CNC-machined connecting rod with laser-engraved logo

The kit includes high-speed SKF C4 bearings with a TN9 cage, capable of supporting up to 20,000 RPM, together with Corteco/KOK Viton seals to guarantee sealing and durability.

Contents of the bearings and seals kit

• 2 x SKF 6204 TN9 Bearings - 20x47x14
• 1 x Seal 20x40x8
• 1 x Seal 28x48x8

Requirements and recommendations

• The VForce 4 Yamaha YZ 85cc reed valve must be used.
• Combine with the recommended VCR-RD11DT.54 cylinder head
• Check balancing before installation to ensure warranty validity.

Application

Kit valid for Yamaha DT 50 Portugal, Yamaha DT 80 LC, Yamaha RD 80 LC, and Yamaha TZR 80 LC engines. Recommended for high-performance sport builds and displacement increase to 100cc.

Main features

• 100cc BigBore cylinder with Vertex piston and 5 transfer ports
• HQ Racing 43mm crankshaft with 85mm connecting rod and optimized precompression
• High-speed SKF C4 bearings and Viton seals
• Maximum performance in Yamaha DT LC/D and TZR 80 LC engines
• Complete 100cc BigBore-type build

Important

It is essential to carry out balancing checks before installing the assembly. Any balancing fault detected after installation may void the manufacturer's warranty.