Starting problem

[Knowmad]

A friend has a 1978 CB750 (K4?). Says it ran fine at the beginning of summer and then he left town for a couple of months and now the bike won’t start. Won’t even crank. You press the starter button and everything dims but no nothing. No cranking, clicking, nothing. He doesn't have tools or diagnostic capabilities. I told him it sounds like a short. Maybe the kill switch. I will head over there this weekend. I thought I would first put an alternative power source to the jump it from a charger. See if that does anything. Otherwise, what is the recommended logical troubleshooting process?

[CB750Winger]

  Easy things first, check battery connections, acid and charge. If you have a voltmeter, see what the battery reads but I would say put a charge on it and see what happens. Many batteries left un-attended will lose charge in two or three weeks sometimes. If you get it to fire, it's probably going to run like crap for a while.      Paul

[gonebiking-2]

Agreed. The first thing to go is the battery. After experiencing that problem shortly after I purchased my 750 brand new, the same thing happened. Moral of that story was to buy a charger that just kept enough current going in to keep it topped up. After that, if I new I was going to be away for anything more than three weeks, just plugged the charger in and when I got back home , bingo started first time.

[CB750Winger]

  It wouldn't hurt to get a battery tender if you park the bike for more than a couple weeks. A battery tender is not a charger, it just keeps the acid in the battery active. I keep one on my Goldwing if it's going to sit for more than a week due to the fact the clock in the stereo is live all the time. My battery has 5 years on it and going strong. I've got one on my 750 as well. Paul

[750fourK]

first charge battery, next check fuse 15 amp, take off left side cover to get to fuse box, if still nothing there is a starter problem , not getting power to starter, check solenoid ( next to fuse box) , again on left side under cover ,check connections, these bikes are reliable so its usually something simple.