Introduction

Have you ever wanted to improve your 68cc gas bike's performance? This FastFix will help you improve your bikes performance and speed.

Clean the compression head with an alcohol based cleaner to ensure a perfect fit on the engine.
  • Clean the compression head with an alcohol based cleaner to ensure a perfect fit on the engine.

    • DO NOT use soap or an acid based cleaner. They will ruin the compression head.

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Detach the rubber CDI from the spark plug by gently pulling up and away from the engine. The rubber part that grabs the spark plug on the CDI is very delicate and may break with excessive force, use minimal force
  • Detach the rubber CDI from the spark plug by gently pulling up and away from the engine.

  • The rubber part that grabs the spark plug on the CDI is very delicate and may break with excessive force, use minimal force

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Place the spark plug tool on the spark plug and twist it counter clockwise to loosen it. After loosening the spark plug all the way, remove it by lifting up.
  • Place the spark plug tool on the spark plug and twist it counter clockwise to loosen it.

  • After loosening the spark plug all the way, remove it by lifting up.

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Place your 3/8"  wrench on any of the four top cap nuts on the compression head currently on the bike. Turn the wrench counter clock wise to loosen the cap nut and remove it. Then remove the washer and the locking washer. Repeat this for all cap nuts. Keep the washers and lock washers with the cap nut they were with on the compression head, it is not recommended to mix them up.
  • Place your 3/8" wrench on any of the four top cap nuts on the compression head currently on the bike.

  • Turn the wrench counter clock wise to loosen the cap nut and remove it. Then remove the washer and the locking washer. Repeat this for all cap nuts.

  • Keep the washers and lock washers with the cap nut they were with on the compression head, it is not recommended to mix them up.

  • Use the flat head screw driver to remove washers stuck to the compression head.

  • Sometimes the bolt gets stuck on the nut and comes out, do not worry, this is normal.

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Remove the compression head by lifting up. Remove the head gasket from the engine. Sometimes the head gasket gets stuck to the compression, remove the head gasket if it is stuck to the compression head. Clean metal head gasket with the rubbing alcohol.
  • Remove the compression head by lifting up.

  • Remove the head gasket from the engine. Sometimes the head gasket gets stuck to the compression, remove the head gasket if it is stuck to the compression head.

  • Clean metal head gasket with the rubbing alcohol.

  • Reinstall metal head gasket on the engine after cleaning.

  • Without the head gasket properly cleaned and replaced onto the engine the engine will not run properly.

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Place the new compression head on the engine. Place the washers and locking washers back in their respective places and place the cap nuts on top. Hand tighten the bolts. Place the washers and locking washers back in their respective places and place the cap nuts on top. Hand tighten the bolts.
  • Place the new compression head on the engine.

  • Place the washers and locking washers back in their respective places and place the cap nuts on top. Hand tighten the bolts.

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This is important information for the next few steps. This is nut #1, the one on the  right closest to the camera.
  • This is important information for the next few steps.

  • This is nut #1, the one on the right closest to the camera.

  • This is nut #2, the one on the right farthest from the camera.

  • This is nut #3, the one on the right farthest from the camera.

  • This is nut #4, the one on the left closest to the camera.

  • Pay close attention to the relation of the nuts to the carburetor and the exhaust.

  • If you are looking at the engine from this view the handle bars will be to your right and the seat will be to your left.

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THE NEXT  TWO STEPS ARE VERY IMPORTANT AND MAY HINDER PERFORMANCE OR CAUSE ENGINE FAILURE IF DONE INCORRECTLY. Using your 3/8” wrench,  place it on the first cap nut labeled in the picture above. This is the cap nut in the red circle. Tighten it 2 full turns clock wise.
  • THE NEXT TWO STEPS ARE VERY IMPORTANT AND MAY HINDER PERFORMANCE OR CAUSE ENGINE FAILURE IF DONE INCORRECTLY.

  • Using your 3/8” wrench, place it on the first cap nut labeled in the picture above. This is the cap nut in the red circle. Tighten it 2 full turns clock wise.

  • Next, place the wrench on cap screw three and tighten it 2 full turns clock wise. Cap screw three is the one labeled with by yellow arrows or circles.

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Place the wrench on cap screw two and tighten it 2 full turns clock wise. Cap screw three is the one labeled with by orange arrows or circles. Place the wrench on cap screw four and tighten for 2 turns. Cap screw four is labeled in green.
  • Place the wrench on cap screw two and tighten it 2 full turns clock wise. Cap screw three is the one labeled with by orange arrows or circles.

  • Place the wrench on cap screw four and tighten for 2 turns. Cap screw four is labeled in green.

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Repeat the tightening pattern two more times to make sure that all screws have the same amount of tightness one them.
  • Repeat the tightening pattern two more times to make sure that all screws have the same amount of tightness one them.

  • The tightening sequence is 1 to 3 to2 to 4, and repeat. Or color wise, red to yellow to orange to green.

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Use the spark plug tool to reinstall the spark plug by screwing it in clock wise. Reattach the rubber CDI to the spark plug.
  • Use the spark plug tool to reinstall the spark plug by screwing it in clock wise.

  • Reattach the rubber CDI to the spark plug.

  • Make a quick visual inspection to make sure nothing looks out of the ordinary.

  • You have now installed a new compression head on your 68cc gas bike!

  • Go out for a short ride to test the new compression head to make sure all components are properly installed.

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Finish Line

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Jake DeBoer

Member since: 09/29/2015

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Cal Poly, Team 15-1, Green Fall 2015 Member of Cal Poly, Team 15-1, Green Fall 2015

CPSU-GREEN-F15S15G1

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