Name: 13X33X100L CONNECTING ROD (JIS SCM420 CHROMIUM-MOLYBDENUM STEEL)
Brand: YUMINASHI
SKU: 06381-ZHO-88016
Price: 2256 THB
Availability: InStock

Description

● 100L JAPANESE JIS SCM420 CHROMIUM-MOLYBDENUM STEEL CONNECTING ROD / 13-PIN (13 X 33 X 100MM) (ZONGSHEN 125 H/O FIDDY RACER | DAYTONA DT125 (LC20-20) NARROW-PITCH)

● Yuminashi JIS SCM420 Forged Connecting Rod Upgrade (Zongshen 125 H/O Fiddy Racer | Daytona DT125)

● When building a pitbike engine for the track, peak horsepower means nothing if the engine cannot reliably finish the race. For racers utilizing the Zongshen 125 HO or Daytona DT125 LC20-20 Narrow Pitch platforms with a 54mm stroke, the factory connecting rod is a known critical weak point under high-RPM stress.

● We have engineered a direct solution using Japanese OEM-grade metallurgy to keep your engine in the safe tuning margin, even when you push it hard on the circuit.

● The Risk: The Stock 20CrMnTi Rod

● The factory Zongshen/Daytona connecting rod in these Chinese engines is forged from 20CrMnTi steel. While cost-effective for standard street use, this material becomes notoriously brittle when subjected to mass-production carburizing processes.

● At high engine speeds, the greatest stress on a connecting rod is tensile—the physical stretching force applied at Top Dead Center (TDC) during the exhaust stroke as the rod yanks the piston back down. Because 20CrMnTi lacks sufficient core ductility, this tensile shock can cause the rod neck to simply snap without warning, resulting in catastrophic engine failure.

Maximum Safe Piston Weight: ~110g
Maximum Safe RPM Ceiling: 9,200 RPM

● The Solution: Yuminashi JIS SCM420 Forged Rod #06381-ZHO-88016 (100mm)

● To solve this material weakness without altering the engine's natural geometry, we are utilizing the Yuminashi JIS SCM420 Connecting Rod.

● Because the stock Zongshen/Daytona rod is already 100mm center-to-center, the Yuminashi rod serves as a direct drop-in replacement. By keeping this length on the 54mm stroke crankshaft, you retain the highly efficient 1.85 rod ratio. This geometry is already excellent for keeping side-loading and cylinder wall friction low, but now you have the metallurgy required to actually exploit it on the track.

● Forged from premium JIS SCM420 Chromium-Molybdenum steel, this Yuminashi rod offers a vastly superior structural profile. The carburizing heat treatment creates an incredibly hard surface (HRC 58-62) at the big and small ends to serve as bulletproof bearing races. Meanwhile, a precise copper-masking process keeps the core and main beam highly ductile. Instead of snapping under the severe tensile shock of top-dead-center (TDC) loads, the SCM420 alloy flexes and absorbs the stress safely.

※ Engineering Note: Because the 100mm length remains unchanged, your piston deck height and squish band clearance remain exactly as they were, making the mechanical installation straightforward while drastically raising your thermal and mechanical ceilings.

● The Yuminashi SCM420 Safe Operating Limits:

Maximum Safe Piston Weight: 120g – 125g (Safely accommodates heavier, big-bore piston kits)
Maximum Safe RPM Ceiling: 11,500 – 12,000 RPM (Continuous track load)

SMART SHOPPER TIP:

※ IF YOU ORDER 2 PIECES THEN WE SHIP THEM FOR THE SAME PRICE AS 1, AND YOU RECEIVE A 10% PRODUCT DISCOUNT ON TOP OF IT!

※ B2B:

Purchases between 2 & 4 pieces of this product will receive a 10% DISCOUNT
Purchases between 5 & 9 pieces of this product will receive a 15% DISCOUNT
Purchases between 10 & 19 pieces of this product will receive a 20% DISCOUNT
Purchases between 20 & more pieces of this product will receive a 25% DISCOUNT
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