How to Balance a Two-Stroke Crank
All crankshafts are machine-balanced at the factory. The cumulative weight of the piston assembly and connecting rod must be identical to the counterweights of the crankshaft. Perfect balance is required to optimize performance and reduce wear and tear on the internal components of the engine. The easiest and most cost-effective way to balance a two-stroke crank is static balancing, which is when the parts aren't moving. Skillful welding is required.
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Things You'll Need
- Wooden block
- Electronic digital scale
- Grinder
- Welding supplies
- Acetylene torch
Instructions
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1
Remove the crankshaft from the engine by taking off the flywheel, bearing plate and everything else connected to the PTO end of the crankshaft. Bump this end gently with a piece of wood to remove it from the engine block.
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2
Place the digital scale on a level surface. If the surface is not level, the scale will not read accurately. The scale must have the ability to read to one-tenth of an ounce.
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3
Weigh the piston, rings, pin, clips and connecting rod together on the scale. Record this weight.
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4
Weigh the crankshaft. Write down this number and compare it to the other measurements taken.
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5
Grind off small portions of the counterweights on the crankshaft if the crankshaft is heavier. Do this in minimal amounts and recheck the weight of the crankshaft. Grind even amounts from both counterweights to keep the crankshaft balanced.
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Weld more weight onto the counterweights if the crankshaft weighs less than the other parts. To prepare the counterweights for welding, heat them first with an acetylene torch. This burns the oil off. Fill in the factory-drilled holes with a heavy metal, such as tungsten steel weld. There may be pins on the counterweights that can be removed to allow the holes to be filled in. Add equal amounts of weld on each counterweight to keep it balanced.
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