QuestionHELLO, I HAVE BEEN WORKING ON THIS BIKE AND HAVE NOT BEEN ABLE TO GET IT TO RUN. I HAVE SPARK,FUEL AND THE TIMING IS RIGHT ON AS FAR AS I CAN TELL BUT IT STILL WON'T RUN. MY BATTERY IS LOW, COULD THIS BE IT? I read that somewhere. Any ideas would be helpful.
Thanks
AnswerEd, Does it have compression? Are valves adjusted? Clearance is only .002", (SET COLD on compression stroke) but critical for operation. Should have over 150 psi in the cylinder.
Is the carb cleaned out, float level set, idle jet open, air passages okay, air mix screw adjusted properly? Fresh spark plug?
Is the CAMSHAFT loose in the head? The first generation CB100-125s had one-piece heads with cutaways for the cam lobes to enter the head, so cam bearing surfaces are reduced and cams get to wobbling around in the head and that takes the ignition timing with it. Point gap should be kept down to about .012" -.014" at highest part of the point cam lobe. Did you check the mechanical spark advance, located behind the point plate for proper operation? If they get stuck/seized, the timing will never advance and will be hard to set in the first place. Be SURE that the points are just opening at the F mark alignment on the flywheel. Test with 6v test light or volt meter to be sure. If cam bearings have more than about .006" sideplay it will be really hard to get it timed properly.
Yes, these ARE battery operated ignition systems and the 75 models have the ALWAYS ON headlights that suck juice from the ignition system. Until you get it running well, disconnect the headlight bulb. Charge the battery up all the way... should be around 7.2v fully charged. If it is more than 2 years old, replace it with a fresh, fully charged battery!
Bill Silver
www.vintagehonda.com
