1972 Honda CB750

[DanMad]

I have a 1972 Honda CB750. Had it for about 6 years. Never changed the battery, and the bike has always run well and is well maintained.
I never let the bike sit longer than two weeks, and if I do, I keep it on a tender. It has a Yuasa AGM battery in it now.

Over the past several days, Ive noticed that its starts very weakly and seems like its going to die if i use the started button. When I kickstart it, its fine. Battery sitting voltage is about 12.6

Last night I took it out and it was hard to start with the starter button. The lights dimmed. But when I kicked it, it started up fine. I took it on a 8 mile trip, parked for a few hours and when I started it again using the starter button it started right up and seemed strong.

I let it sit overnight. Went to start it this morning and though sitting voltage read 12.5v it the starter button made clear there wasnt enough power to start it. Kicked it and it was fine.
Never had a parasitic draw on this bike, so Im thinking its a dead battery cell. Thoughts?

Also, Im thinking of throwing a Shorai battery in it.

 

[dirtdigger]

With the age of that battery it is more than likely bad. Voltage would be lower if it had a bad cell, it is probably sulphated. Either way it sounds like it is bad as long as grounds and cables are good.

 

[DanMad]

With the age of that battery it is more than likely bad. Voltage would be lower if it had a bad cell, it is probably sulphated. Either way it sounds like it is bad as long as grounds and cables are good.

Thanks very much for the quick response. I have other old honda's with Shorai batteries in them. Im ordering one for the 750 tomorrow. An old timer elsewhere told me its not necessary to upgrade the reg/rec as so many ppl do. Maybe later on down the road I'll change it, but for now I will drop the battery in.