Charging system

[bellison80]

Alright guys, I just gone done with carb rebuild/clean, new boots airbox to carbs, new plugs, new wires, kreem lined the gas tank, rebuilt front master brake cylinder, all this since early winter till now. Finally go it running right and went out for a cruise. Went about 15-20 miles, came back home and before putting it in the garage tried to start it again to find a dead battery. This winter I had stored the battery inside and last year until I put it up seemed like there was no trouble with charging system, the battery always held a charge, the bike always started. I put the battery on a trickle charger prior to taking it out.

Now I do have some background info on the bike for what its worth. I bought it for $500 bucks from my friend who became frustrated with sorting out its kinks. Turns out at the time it was float needles and off I rode until winter, knowing that I had a laundry list of things I wanted/needed to do to make this a reliable rider.

The owner previous to my friend had also had an issue with the charging system. He was not a hands on motorcycle rider and let the local Honda dealer sort out the issue. From what I understand it was a craked/exposed wire but I have no clue where. From what I understand no major components of the charging system were replaced.

I have tracked necessary replacements through Vintage cb750.com......they are pricy!!! I took some time reading in the clymer manual as well but as always I learn best watching others or communicating with those that have had the experience and know how. So I am wondering where to start. Looks like I will need a special tool just to pull it apart, 8 bucks on the same site as the other parts. Electrical is not my forte and I would greatly appreciate what you guys have to say.....you have already been truly resourceful as I keep checking things of the list to get this thing back on the road. I am including a photo I took today right before I pushed it back into the garage haha.

[shinyribs]

Well,I cannot help you with the charging questions.Sorry. Just wanted to say that the bike looks great! Also,I thought that particular style of Comstars would not fit a DOHC. Apparently they will.Good to know.Good luck with your issue.

[bellison80]

Thanks Man, I am gonna put the trickle charger back on it and test the battery before I do anything else. I actually talked the one of the previous owners tonight and he informed me that the stator was replaced at the honda dealer so I guess that leaves the regulator or hopefully its just the battery. I have never tested one but have been reading up and just watched a few youtube videos....seems straight forward and I already have a volt meter.

[shinyribs]

Oh,I forgot to add. My bike and battery have been doing fine. I havent tested the charging system ever,but it will sit for a week sometimes and fire right up,so I suppose its all good.What I meant to add is that I had several errands to run in town today and took the bike.Parking is much easier that way! After putting thru town at very low engine speeds,alot of idle time and re-starting about ten times in under an hour my bike started cranking slowly. I ran my last errand in 3rd gear keeping the rpms around 3000 and it started fine after that.It was only about a 5 minute trip. I have heard alot of talk about these bikes needing some rpms to charge.I guess putting at 25mph in 5th gear doesn't do the trick. Just putting that out there for what it's worth.

[Piute]

   Hey Chrome Ribs Ya-no ,
how some alternators have to hit past 3k on some Chevy's to kick in but don't have to stay there,but can put in a die-oid ? to prevent having to CAN THIS be the case with 750s.
  ..................................bring on the negative comments

[ksharp]

MAN i had the same problem same bike everything, what u need is to do a little ready on how to use a multi meter and realistly if u thought u would benfit from an ownersmanul u could learn how to use a multi meter, this is what the problem could be either the rectifier or the stator/router, trust me i went though like all splices in my bike thinking i got the issue and its always miss leading.

start by re charging the batt its most likely not the battery, but there are ways of testing batts which i dont know, but when the bike is started u take the leads of your multi meter and hold them on each post of the batt and even if you get somthing like 13 to 16 volts it dosnt always mean its providing a constant charge to the a battery.

in the manual there will be a process on testing the rectifier and checking resistances of all the leads one by one and that will rule out your rectifier, where my problem was and most likely yours and im sure people will back you up u need to check the router, the stator when u pull off the cover you will be able to check them both, and i believe its on the right side engine cover, when u check the stator and everything looks good the last thing u need to do is check the router and this is how



thoes copper lines are called "SLIP RINGS" there are also two leads on the engine cover to check to make sure they arnt worn past the scribe line, if u read 0 ohms on the two slips rings YOU NEED A NEW ROUTER AND U ALSO NEED SOMETHING CALLED A STATOR PULLER, u can find a used router for a dine a dozen from old biks shopes or on ebay there nothing you will need the stator puller to take it out,

the only thing i can say is before you loose your fucking mind testing leads and random splices like i did test the main components first ! u will find the fault i will personally walk u thought it becasue theres nothing worse in knowing your rolling around on a bike on borrowed time ....


good luck let me know if u need any more claifrication

[bellison80]

Very well said at the end. Thanks for the info. I have some good things to go on but will post an update when  I make some progress.

[mikefootusa]

The rotor should read 5 ohms across the slip rings...the rotor is the most common part to fail.  Problem is...when it fails it can take out the reg/rec as well.  Been dealing with same problem for three months now.

Check out these videos:http://www.youtube.com/watch?v=kHwrRRFzccA&feature=player_embedded


To remove the rotor...you need a ROTOR PULLER!