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1979 Honda CB 750

4238 Views 13 Replies 7 Participants Last post by  Jakeochsner29
I just got this CB 750K and i was wondering what could be wrong with it. I cant started accept if i jump it from cars battery.. When i started it works fine but the baterry is not charging... first when i got it It started on the button fine. Now i have to jump it from cars battery.... can someone please tell me what could be wrong... Thank YOU
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A bad battery springs to mind. Even if not, almost certainly an issue in the electrical system.
Honda CB 750 K

how can i fix it I am starter. I know little bout bikes but very interested to learn. What can i do to the battery spring.. Some people told me it might be altinator but my lights work fine when i ride the bike and signals so i am not sure.......... It just wont start unless i jump it from car to bike....
You're right, it's unlikely to be the alternator. If that were shot, none of the electrical systems would work. My advice is to take it to a garage and let them replace it. If you really want to learn how to do it yourself, you could ask them to let you watch. Alternatively, there might be instructions in your bike's owner's manual on how to change the battery.
In your case 99 times out of 100 the battery is toast.

Changing a battery ain't hard just follow the directions on how to fill it with acid. Bike batteries are generally shipped dry and the acid is in a seperate jug. Fill it to between the lines on the side of the battery and be patient, it takes awhile to fill the whole way and let all the air bubbles come out before you move to the next cell. Do not over fill it and keep the sulfuric acid away from your eyes and skin. Matter of fact, wear safety glasses. Then you'll want to trickle charge it on like a 2 amp setting on a charger for however long the instructions say to. Again RTFI (Read The Fricken Instructions). Keep it away from open flames or sparks while charging and don't smoke around it. Battery charging makes hydrogen gas, albeit small amounts but it can catch fire when exposed to flames or sparks.

I'm going to assume your battery is under the seat so you'll need to flip the seat up. Then you remove the rubber strap if yours has it. Next you remove the terminal leads positive side first. Pull the battery out of the box. Clean all gunk and stuff out of the box before puttin' the new battery on. If you see white flakey stuff in there mix up some baking soda and water to neutralize the acid. I would touch up any missin' paint while you have it out. Dispose of the old battery properly.

After you get all that done and the new battery is fully charged and ready to go put the vent hose on it. Route the vent hose while sliding the battery into the box, keep the vent hose away from the exaust, hot surfaces, and any chrome parts. Replace the terminal leads in the right spots, positive side first then the negative. Replace the rubber strap that holds it down or however it's held in there, if yours is missing get one. Put the seat down and try it out.
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Would the battery come with a charger, or is that a separate piece of hardware he'd have to buy?
No, you would have to buy one. You should have one anyways if you're gonna ride bikes, at least a battery tender or trickle charger. You can get them for like $20 at Wal-Mart. You can also get batteries there and they ain't too bad.
Honda CB750K

The battery was replaced like 4 months ago and i ckecked all the acid in it and its ok.. the acid sits on the line........ but it doesnt charge when i ride the bike.............

Can i just put new acid in it because battery is new 4 months old

It doesn't take much to fry a motorcycle battery. :( Might as well start with another new one. If you still have the receipt you'll be able to swap it out with hardly any prorated cost.:)

Before reinstalling the new battery double check your ground wire ( the negative cable), make certain that all the cables are GOOD - that they aren't corroded. Corrosion creeping up inside the cable will increase the resistance and create problems for the charging system.

MAke certain that the battery you have purchased has the proper amperage! ANd that it is actually a motorcycle battery! When I went to get a new battery for my bike that had been sitting for a long time, they tried to sell me a lawn mower battery! If I wasn't paying attention - I'd have wasted a long trip into town!

Cheers, Kim
Can i just put new acid in it because battery is new 4 months old
Your best bet is to get a new battery and start from there. That's what I had to do with my bike when it wouldn't stay running. (I also changed the plugs)
I have a 1980 cb750k and am checking around to see if anyone knows how to adjust the carbs to the correct mixture. 3 of the 4 pipes are turning yellowish because I think they are burning rich. Any suggestions?
i had the same problem with mine for awhile too. first off, be careful jumping it with car batteries as the it could overload and ruin your motorcycle battery. i've done it twice. second, check the stator.
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