Honda modification
- Thread starter sailorhuete
- Start date
The Honda GXH50 does indeed have an automatic compression release.
It is integral to the permanently assembled cam assembly. The "cam lobe on the cam lobe" that Dagwood made reference to is a pin that projects from the side of the gear at low RPM, and retracts when the RPM's increase. It contacts only the exhaust follower. The mechanism is visible only from the back side of the gear.
This picture is of the back side of a Honda GXH50 cam:
It is integral to the permanently assembled cam assembly. The "cam lobe on the cam lobe" that Dagwood made reference to is a pin that projects from the side of the gear at low RPM, and retracts when the RPM's increase. It contacts only the exhaust follower. The mechanism is visible only from the back side of the gear.
This picture is of the back side of a Honda GXH50 cam:
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The shop did the repair all under warranty and billed Honda. They messed up and put my cam in timed incorrectly. I had to take it back after about 5 hours of riding too slow. It was in one tooth retarded. They didnt charge for that either. They also said that they did not attempt to remove the de-compression lever. I bought a new cam gear from Honda through the shop and I am going to remove the decompression assembly. The lever must have broken from a back fire kick while starting. I start it fast now to avoid any damage.
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I found that the decompression lever is riveted into the cam gear and can be drilled out to remove the assembly. Before I installed the cam gear with the decompression lever removed the cam gear failed in the same manner at only 160 hours. The lever cam apart as far as protruding 1/8" through the valve cover. I shut the engine off after an hour long ride and heard a backfire. I could not start the engine afterwards. My local Honda shop rebuilt the engine and replaced the belt valve cover and gasket and cam gear all under warranty and billed Honda. I would swap out cam gears for the one I removed the decompression assembly from but at 170 hours the exhaust studs have vibrated the threads out of the holes where the muffler can bolts the the exhaust port. I was able to take the stud on the flywheel/coil side of the cylinder and turn it around and use the longer threads to bite into the cylinder threads deep enough to hold. On the other side the threads are too stripped and I have safety wired the stud into place by tying the stud down using of the top bolt mount for the pull start as an anchor to hold the exhaust stud and exhaust can firmly up against the exhaust port. I also took a disposable thin aluminum baking pan and cut it to size and fit it into the portion of the plastic engine cover that surrounds the exhaust can as a heat shield. Is there an exhaust manifold on the market that will fit the Honda GX35?
The decompression system has failed again at 176 hours. During cold starting, the portion of the system that actually does the decompression action or the "decompression lobe" got knocked out of place and then came completely out of the cam gear. The hard plastic cam gear is still intact and the lever that engages and disengages the decompression is still mounted solidly to the cam gear. I was starting the engine and then it locked up. I pulled off the valve cover and found this. After removing the piece that came out of the cam gear, I re-installed the valve cover and turned the engine over with no problem. The engine is now not starting. When the decompression lobe kicked out of place it lodged itself between the cam gear and the valve cover. When I pulled the starter again before I could have realized what had just happened, the crank turned but the belt and cam gear stayed in place. The timing must be reset.
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I reset the cam timing and the engine runs perfectly fine now. I did finally due away with the vent system on the inside of the gas cap. Even though it is designed to be a vented cap, after sitting at the bike rack all day, the tank would have a great deal of pressure in it. The cap has to be secured tightly or it falls off but in doing so it prevents the tank from letting air into the tank to displace the fuel being used while the engine is running or if the fuel heats up while not in use the pressure cannot escape. I noticed this the first time that I rode when I had to sop after two minutes of riding to open the gas cap to relieve the negative pressure that had developed in the tank. I removed the ventilation device from the inside of the cap entirely and put a 1/4 inch hole in the center of the cap. I replaced the vent system by threading a 1/4 threaded plumbing fitting with a 1/8 pipe barb into the hole I drilled into the cap and attached a 3/16 inch fuel line from a lawnmower fuel line kit to the the pipe barb fitting. I tucked the hose in just under the clip for the air cleaner and left it full length.
