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banana4monkey

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Based on the troubleshooting of this Big Red I will disassemble the top end of this motor to further investigate. To remove the cylinder head and cylinder of this three wheeler the engine will need to come out of the frame. Before I get the engine out of the frame components like the rear fenders, exhaust, recoil starter, and carburetor will need to be removed. I will also drain the engine oil. I got lucky when removing the exhaust in that the whole stud came out of the cylinder head. Normally these studs break and you have to drill the stud out.

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Rear fenders removed

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Draining engine oil

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Complete exhaust stud being removed.


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banana4monkey

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I got the engine out of the frame and on the workbench for disassembly. I had to remove the starter, drive shaft boot, and the motor mounts. The lower motor mount bolt was a real pain. The steel bolt oxidizes and seizes up where it passes through the motor. It is not in a good spot. I ended up tipping the 3 wheeler on its side so gravity will take the penetrating oil down and I could try to pound it out easier with a hammer and an old railroad bolt. It took a lot to get this bolt off and this is not the first time. I had a 1985 Honda ATC 250SX that had the same issue. Next time I will drill some pilot holes in the area where the bolt passes through the motor to get some penetrating oil in where it is needed and fill the holes after the bolt is out. Now it is time to start the motor disassembly.

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driveshaft boot removed

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starter removed

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ATC up on its side

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Using a heavy duty railroad bolt to pound the motor mounting bolt through

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Motor ready to come out

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Motor on the workbench

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banana4monkey

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Reply with quote  #3 
Now that the motor is on the workbench it is time to start breaking it down. This is a fairly simple process as long as all the fasteners come loose. In this case they did so it came apart quickly. See pictures and captions below for details. Upon initial visual inspection I did not find any issues but in the next post I will do a more detailed inspection.

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motor on bench

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cdi cover off IMG_5615.JPG  IMG_5616.JPG  IMG_5618.JPG   
removing the cdi trigger and rotor assembly
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removing rocker cover

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cylinder head and camshaft removed
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evidence of oil leaking around the cylinder head gasket area

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Top end disassembly complete. Now time to move on to cleaning and inspection.

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banana4monkey

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Oops I forgot to post the cylinder head disassembly. I used a valve spring compressor to remove the keepers and disassemble the valves. The valves need to be disassembled for inspection and to replace the valve stem seals. See pics and captions below for the procedure.

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Cylinder head before disassembly

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The valve spring needs to be compressed to remove the keepers.

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Using the valve spring compressor to remove the keepers and disassemble the valves.

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Valve spring removed. This is the oil seal. It can be removed carefully with a flathead screwdriver.

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Valve assembly removed.

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Cylinder head removed and ready for inspection.

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