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Common problems and solutions

Common Issues and Points of Attention for Your G50 Engine

Every JLO engine is now more than 50 years old. Because of their age and high number of running hours, these engines deserve extra attention during an overhaul. Keep the following points in mind to bring your engine back to optimal condition.

You’ll find the parts you need in our webshop. Have questions, or want parts or a complete engine overhauled? Feel free to contact us!

Cylinder and Piston

  • Cylinder head flatness: Check whether the cylinder head is still flat. Heat can warp the aluminium, causing a leaking head gasket. We can resurface the head for you. Please contact us for this.
  • Piston clearance: The clearance between piston and cylinder must not exceed 0.09 mm. Also check whether the cylinder wall is scratched or whether the honing marks have disappeared. In either case, an overhaul is required.

Crankshaft

  • Bearings: Check not only the small-end bearing but also the big-end bearing. All JLO crankshafts are more than 50 years old, so we strongly recommend always having the crankshaft overhauled. Even without noticeable play, the big-end bearing is often affected by moisture. Contact us for a crankshaft overhaul.

Clutch and Drive

  • Correct oil: Use the correct oil for your JLO Piano engine to prevent damage to the belt. Suitable oil is available in our webshop.
  • Clutch plates: Check that the clutch plates have not worn grooves into the clutch housing.
  • Pinion and clutch basket: Check that the pinion and clutch basket are not damaged. This prevents the belt from snapping prematurely.
  • Tuned engines: On tuned JLO engines, always replace the clutch plates, roughen the steel plates and fit extra-strong pressure springs.

Ignition

  • Noris ignition: Replace the yellow/orange wound ignition coil as a preventive measure. Older coils quickly short to ground when hot. The new modified coils in our webshop no longer have this problem.
  • Lighting coil: Check that the insulation of the lighting coil is still intact. If it shorts to ground, the lights will stop working or won’t work properly.
  • Bosch flywheel: Always check the riveted magnets, as they often come loose.

Pedal Crank Axle and Gearbox

  • Pedal crank axle: Inspect the crank axle for cracks and fractures, especially around the keyway.
  • Shift block (G50 3V): On G50 3V engines, the shift block is often worn. Its corners must be sharp, not rounded. Does the engine jump out of gear while riding? Replace the shift block immediately to prevent damage to the 2nd gear.

View all JLO parts in our webshop or contact us for an overhaul.