Honda SL350K1 courtesy of AHMC
Of course, it was a kickstart-only K1, I think, Orange paint and had the correct black mufflers installed. That’s what showed up when they strapped it to the back of a Jeep and drove 3 hours to meet me at home. I got a quick rundown on what had been done and what had been happening, so based on that information, I decided to check the timing first. The owner had mentioned that the engine had backfired when he was trying to start it, leading me to think that the point cam had been installed 180 degrees out of normal.
As I began to remove the point plate and advancer, I was told that the advancer weight pivot washers and e-clips were missing! With the point plate removed, sure enough the advancer springs were stretched out and the retainer hardware was not in place. Removing the spark advancer, I noted a 369 product code stamped on the advancer base, indicating that it was from a CB360! I dimly recall having a 350 spark advancer that came to me years ago. After a bit of digging, it made itself known and it was marked 312, which is correct for an SL350K1-2. The springs were tight and the point cam in good shape. I added a bit of Bosch point cam lube and dropped it onto the end of the camshaft.
Turning the engine over, to check the valve lash, which is supposed to be at .002 intake and .004 exhaust settings. But the index marks on the ends of the tappet adjuster shafts were all in the 10 and 2 o’clock positions, instead of about 8 and 4 o’clock. The valves had been set on the wrong stroke (overlap), so the actual valve lash was probably an 8th of an inch. Once the valves were set, and the ignition timing reset after replacing the point plate, it should have been a candidate to start right up.
Unfortunately, all it did was slowly kick over with no signs of life. The plugs were pulled out for inspection and a compression test. They looked dry, even after all that kicking. The engine had never been fired in the last 5 years, so I thought that the cylinders and rings were running dry and not creating a good suction in the intake tract. I mused about the condition of the intake manifolds and was told that they were originals. This could lead to intake air leaks if they are 50+ years old. I dropped the float bowls and found a loose main jet in the bottom of the bowl! I was so glad that they were present to watch me troubleshoot and to witness what I was finding. The next step was to check the mixture screws which were out 2 turns instead of just one turn as specified. I removed the idle jets and made sure they were clear and the float level was set correctly. A number of attempts were made to bump start the bike down the driveway, but all it did was leave black tire marks from the installed knobby tires. Still no signs of life.
What I thought would be a one-hour maintenance visit ran into 3 hours and still no success. The battery voltage was around 10.8-11v, so it should have had enough juice to light off the cylinders. I was running out of ideas and disappointed at the lack of fire in the engine so far. As a last check I ohm tested the spark plug caps only to discover that one was 9.5k ohms, instead of the desired 5k ohms reading. The cap was poorly connected to the plug wire, which wasn’t helping matters. The opposite spark plug cap read out as an open circuit. While we did check for spark with the plugs out and grounded to the head, the combination of BR8ES spark plugs (resistor) and the high resistance on the plug caps were not creating sufficient fire under cylinder pressure. The owner understood what I was doing and what was needed next, so they loaded it back up on the Jeep and headed back to the desert where they were wintering rather than staying in Idaho in January.
Additionally, the kickstarter ratchet was not engaging properly, so the engine was not turning over very much due to restricted kickstarter lever travel. I was sorry to send them off without a running engine, but the lack of parts and other issues prevented a complete success for this pretty, but still sleeping SL350 which has undergone a long Slow/Low 10-year sleep. We all learned a lot about the bike and general maintenance steps needed to make them come alive once again.
With my fused ankle, I was happy not to have to attempt to kickstart the engine this time. I had a similar bike, as part of a 750 swap, some years ago and I recall it was difficult to start up, even when everything was tuned up properly. Give me an electric starter every time!
Bill Silver
aka MrHonda
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