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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 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.

Rear fenders removed

Draining engine oil

Complete exhaust stud being removed.

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.

Driveshaft boot removed

starter removed


ATC up on its side

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

Motor ready to come out

Motor on the workbench

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.


IMG_5614.jpg  IMG_5615.jpg   
cdi cover off     

IMG_5616.jpg  IMG_5618.jpg    
removing the cdi trigger and rotor assembly
removing rocker cover

     IMG_5621.jpg  IMG_5628.jpg     
cylinder head and camshaft removed
evidence of oil leaking around the cylinder head gasket area

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

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.

   16.jpg  17.jpg   
Cylinder head before disassembly

The valve spring needs to be compressed to remove the keepers.
IMG_5631.jpg  IMG_5632.jpg  IMG_5633.jpg  IMG_5634.jpg 
Using the valve spring compressor to remove the keepers and disassemble the valves.

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

Valve assembly removed.

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Cylinder head removed and ready for inspection.                         

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