Re: Electric starting problems - 82 cb750

Posted by gandrolok on Jul 01, 2012; 12:06am
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/Electric-starting-problems-82-cb750-tp4023957p4024004.html

Thank you so much for the advice! I'm just a young enthusiast trying to get started, and I have limited experience. This is my first real bike. It's super helpful to hear from you both.

So I got a ride to Home Depot and bought a multimeter. We got back and checked the voltage on the motorcycle. It was 10.40V when we got back. We waited 2-3 hours and checked it again. It was 10.38V, so it was definitely dropping a little bit over a while.

Hooking jumper cables up to the friend's car and beginning the jump, we measured a boost to 12.70V and it evened out about there after a few minutes. Closer to the boosting car's battery it was 13.8V. At this point I was able to start the bike. The relay clicked and the starter turned and the bike started right up. It seems like everything in the starting line is good.

We removed the jumper cables and monitored the voltage. At 3,000-3,500 RPMs, the voltage remained about constant at 11.8V. When the RPMs dipped down(to idle around 1000-1500RPMs), the voltage dropped pretty quickly, maybe .01-.02V a second. We didn't measure faster than 3500 RPMs.

When I shut the bike off, the voltage on the battery dropped to 11.51V. It dropped to 11.4V before I disconnected the negative cable. The voltage, after the negative cable was disconnected, stayed about the same over the 1-3 minutes I watched it.

Is there a leak of current somewhere? Is the alternator underperforming? Bad battery? Both?

Fortunately, I should be able to ride it the 100 miles back home to a garage where it's safer and easier to work(tools!).

Thanks for all your help!!