1984 Honda CB700SC Nighthawk S starting, battery help.?

[ocean]

Hi everyone. I am new to this forum.

Am posting a post Ive submitted elsewhere about a new to me, used bike I bought nearly two months ago from a motorcycle shop in the south bay.
Was advertised by the motorcycle shop as being in excellent condition, and needing no mechanical work to keep it running, having no mechanical issues.
It ran fine when i test road it.
They first told me that if something went wrong with it within first few weeks i could return it for a refund. But then when i bought it they said they would only sell it as is, which they described as in " excellent condition, needing no mechanical repairs to run".
So I drove it on the freeway home from Santa Clara to my home near Berkely.

Next day I drove it to work, turned it off, key in off position rather than the park position which leaves taillight on.
Came out of work about 5 hours later, and when i tried starting it it would not start. Quickly died to clicking sounds. Long story short, paid another $140 to have it towed to a Berkeley motorcycle shop where they said they put the battery on a charger and looked it over. Could find nothing wrong with it that they could directly discern as causing it to not start. Though the jetting was set a bit high they said, there is a supertrapp exhaust added to the bike which may be affecting it, and the front fork seals seem to be leaking a bit. But the bike started up when i came to the shop to pick it up.
I drove it home, parked it overnight. Came out next morning took it to work,. Came out from work, again - bike would not start! Only weak whirring sound quicly fading to clicking and lights dimming. So had it towed one more time, this time to my home.

Fast forward about a month, Ive purchased a trickle 750ma battery charger, removed battery from bike and have set the trickle charger up on the battery for a couple days. Noticed that the shop i took it to after it failed to start the first time, seem to have not checked the water level of the battery as all water reservoirs were at or below the bottom fluid marker level, so i filled them to top level mark with distilled water before charging battery this time. After a few days on the charger, after reading on charger showed it being fully charged I reinstalled the battery into bike. And the bike did start sluggishly, with choke on most of the way and no throttle. But weakly starting and only with choke on most of the way, it took a couple minutes before the bike started to sound like it was really getting any reliable power while idleing. And still needed choke after 3 minutes or more. Though felt like if I could get it to a freeway and get into higher rpms it would be happy.

Am thinking, from feedback and suggestions from people here and there, that maybe there is an issue with the bike not charging itself during lower rpms? The bike was pretty sluggish to begin with when i rode it in the lower gears. Once into 3rd usually it would suddently surge into life and seem to do quite well at higher rpms & speeds. Lower speeds,rpsm, regular city or stop and go traffic it was sluggish to take off from a stop or slow speed. That tendency significantly increased within the short time ( a week ) after i bought the bike from the shop in santa clara / sunnyvale. And was sputtering and backfiring a couple days before it failed to start this last time.

Any suggestions or advice from people familiar with these bikes and or issues is welcome. I have a manual for the bike, and have been looking through it.

One practical thing that I am not sure how to do is use the 3.5 Digital Multimeter I bought to test the motorcycle battery and charging system as someone suggested to me. But the instructions which came with the multimeter say nothing discernable to me about how exactly, in elementary terms which i seem to require with mechanical areas that I am new to, to use it to take and test readings for the motorcycle battery and charging system. I would rather look simple and ignorant and ask for very specific, detailed step by step explanations on how to and instructions on to use this multimeter for this.

I am green when it comes to working on bikes or mechanical issues as most of my energy has been focused in other areas of life and development.

Though am interested in learning, and would love to barter with someone local ( near Berkeley, CA ) knowledgeable with these bikes - basic hands on troubleshooting, maintenance & repair instruction ( and probably some use of tools as I have some basic tools but lack many specialized tools ) in exchange for professional massage therapy ( for those wondering or with a sense of humor, I do straight bodywork - no prostitution or sexual massage ) and qigong instruction.

[BuzZz]

Charge up the battery again and put your meter across the battery terminals while you crank the bike over. If the voltage reading drops off significantly as soon as the starter kicks in and sucks up some of that stored power, your battery probably has a dead cell. You could confirm this with a battery load tester if you can get access to one. The battery can still read 12+ volts off the charger with a bad cell, it just don't have the amps (power) to turn the starter. This lack of power can also sometimes affect ignition performance and make the bike run poorly under load or when cold.

Either one of the shops who handled your bike coulda/shoulda checked this, and maybe they did and the battery isn't part of the problem, but it has that ring to it.

[coffee_brake]

Like Buzz said, you might have ruined that (already weak) battery when you left the ignition on that day. I did this with a new bike when I left the heated grips on overnight. I didn't know any better and I jumped the bike off thinking that the bike's charging system would recharge the battery. Well, when the battery is very far gone like mine was, it won't take a charge. I had to buy a new battery for a new bike, and learned an important lesson about running relays for ALL accessories! Your battery, having gone dry like it was, has probably not been cared for and may need replacing. This happens suddenly sometimes, a battery failing after weeks of trouble-free riding.
Call it an easy fix and consider yourself cheaply educated if it's the battery and not the charging system. I miss my '84 700S very much, but I am too much of a squid to own a bike that fast and nimble!
Keep us posted....

[insaneV4Honda]

Both BuzZz and coffee_brake are right; the battery is probably weak. My Honda would crank over great and continue to crank but never fire if I left it sit for more than a day or two. I looked at ignition, plugs, fuel delivery and just about everything else associated with starting- except the battery. I figured it out when I completely killed my battery trying to start it and then decided to hook up a battery booster to try to get it started. As soon as I touched the start button, it was running. I don't remember the engine even cranking over a little. I bought a new battery and that solved that problem. Good luck. Sean.

[ocean]

Thank you everyone.

Unfortunately, the bike will not fully crank over again already.
After charging it for days on the trickle charger, when I had first reconnected the battery to the bike, about one week ago, it did start after a few tries and with full choke left on, albeit it finicky. If i tried closing choke within a few minutes after starting it would die.

I did not have a multimeter when i first installed the battery after charging. But bought one within a couple days.

So the bike has been off the charger and sitting in the bike for a few days, close to a week now.

Today, I checked the voltage with the battery connected to bike with ignition / keys off. Reading was fluxuating between 12.2-12.6 Volts.

Then tried starting the bike but it would not start at all this time, again. Just weakly attempted to crank over but would not start, even with full choke.

Then I took the battery out of the bike and read the voltage - 12.21 Volts.

Unfortunately, the bike is again not starting strongly enough to run to even do the other two tests you recommended, with it running.

So Im not sure if i should even bother putting the battery on the trickle charger again to trouble shoot, or just go buy a new battery and go from there.?

[insaneV4Honda]

Replace the battery. A good one will cost $50-60 but it should fix your problem. Overcharging (even if using a trickle charger) will kill a battery. If you could hook up your meter to the battery while you are trying to crank it, that would tell you definitively the condition of the battery under a load. Testing the voltage before and after you crank really doesn't tell you anything worthwhile except what the static potential of the battery is. Like someone said before, if the voltage drops off a couple of volts under a load, you probably have a bad cell.

Messing around with a weak battery can also damage other electrical components so be careful how long you try to nurse the old battery. Good luck. Sean.

[jonnythan]

Replace the battery. A good one will cost $50-60 but it should fix your problem. Overcharging (even if using a trickle charger) will kill a battery. If you could hook up your meter to the battery while you are trying to crank it, that would tell you definitively the condition of the battery under a load. Testing the voltage before and after you crank really doesn't tell you anything worthwhile except what the static potential of the battery is. Like someone said before, if the voltage drops off a couple of volts under a load, you probably have a bad cell.

Messing around with a weak battery can also damage other electrical components so be careful how long you try to nurse the old battery. Good luck. Sean.

Heck, you might be able to get an Everstart at Wal-Mart for $25.

Course, the problem with the electrical system might kill a new battery in short order if it's not fixed.

[ocean]

I bought a new battery today, cleaned terminal connections, and checked several of the fuses on the bike with an inexpensive fuse tester that came with a few fuses from Kragen Auto Parts supposedly for motorcycles.

Using the little tester that has two tiny metal adjustable points to contact fuses and it has green light that goes on if fuses are good.
But the fuses seem to be rather different than the ones in the bike, and i cant even see how to get the fuses out of their whitish plastic housing to replace them even if the fuses i just bought were the same size / shape as the ones in the bike. i thought they would be simply able to be pulled out, but they seem to be joined as part of the white plastic housing they are in and join together with the other white plastic housing connections going to various parts of the cycle.

so i bought a wet cell battery from a battery store in oakland, ca. which they were nice enough to fill with electrolyte and charge up for me before i came to pay for it.
So i took it home, installed it in the nighthawk and after a few seconds of fussing it started up stronger than it has other then the first day i looked at it from the dealer, with choke on 3/4 to full to start and tapering off after a few minutes.

i took it on a ride on city streets to the freeway to help the battery acclimate to its new life and feel how the bike will respond now.
Its mostly been running fine now, although there is still a bit of sluggishness a few times where it felt like it was about to die out when taking off from a paused position at traffic lights a few times. And when i pulled up into a gas station to refill it, as i pulled to a stop the bike sounded like it was going to die before i actually hit the off switch.
And it was backfiring a few times as well.

So though it is starting and running so far with the new battery, still feels tempermental. Like more needs addressing. Perhaps related in part to the being jetted too rich as a mechanic mentioned last month?

Question? - Are all the fuses in the white plastic fuse boxes on the motorcyle live, active fuses with current in them? Because there was one or two fuse ends that did not light up with the fuse tester when i contacted them. Although they were in fuse container next to two ends that did light up as working correctly.
A few photos of the fuses on my bike are here -







One of the fuse types, the bottom photo just above this line of text, where the fuse tester says the 2 fuse ends with the gap between them light up as good, but the row of 3 in same fuse container did not light up, signifying they are broken or not working (?) or do they not matter, are some kind of spares? How do i actually replace these types of fuses? They are not the kind Kragen sold me as being useable for my bike, unless Im really not seeing them correctly?

These are the fuses Kragen sold me -



I also noticed today after putting new battery in, when i came back and looked closer at the spark plugs that the rubber condom looking cover that snaps over them was not fit all the way down to the bottom of them as far as it could go. Unfortunately the spark plug farther back in the crevice was too cramped too reach with my fingers and i tried using a pair of needle nose pliers which made a tear in the soft rubber condom fitting over that spark plug. Though it seems to mostly come back together rather than leaving a gaping hole.
I cant figure out how to get that back spark plug completely covered by the condom rubber joining piece without ripping it more.? Any advice on that? And how far down the rubber condom piece should snap over and come down over the spark plugs? There seem to be a few circular ribs at the bottom of the condom rubber cap that fits over the spark plugs, and i think that it has had more room to snap down over the plugs since ive had the bike.? I took a photo of it after my ride today, the one with the black condomy cover still over it toward the back is covered as completely & incompletely as i think it has been since i bought the bike and have been riding it.? They were both like that actually.
Here is a photo of the spark plugs -



Could that be causing / contributing to some of the not starting, backfiring
dying and poor acceleration issues aside from the battery?

[coffee_brake]

Ocean, those aren't fuses, they're plug-in electrical connectors. Don't take them apart. Your fuse box is somewhere else on the bike. I don't recall where, I'll look in the manual at my local bike shop tomorrow, but you'll probably find it enclosed in plastic somewhere under the seat section. But if all your lights and components are working, then your fuses are all good. They don't slowly go bad, they just break if something's wrong in order to protect that component from frying. Fuses have nothing to do with poor idle and stuttering on acceleration. Bad jetting or dirty carbs often do, though, so I'd look there first. Still, get the electrics now and *then* worry about carbs. Looks like you've done that with your new battery. Remember to check it once a month, even in the winter, to make sure it isn't going dry!

I don't think there's a problem with your plug wires. If they weren't doing their job correctly, the bike would hardly run at all, and you say it's driveable. I assume these plugs are right for the bike but simply different than the original plug wires are made to fit, much like the ones on my '92 Nighthawk that don't quite cover the plugs. Don't worry about them yet. You probably have to remove the tank to get at them. If you do remove the plugs, make sure you get ALL the dirt and sand and funk from around them before you loosen them, so NOTHING gets in those holes and into the engine!!! You will mess up your bike BAD if you let ANY dirt get in there!

It sounds like you really are ready to get yourself a Clymer's manual, it has a great trouble-shooting section and will get you through all minor (and most major) jobs on your bike very well, with great pics and instructions throughout. They cost about $30 from Amazon. There are some dedicated CB700S lovers at www.cbrider.com too, you might look there too.

Keep us posted...

[coffee_brake]

Oh, here:

http://www.nighthawk750.com/maint/Honda ... Manual.pdf

this takes a good long while to load, and has mostly basic stuff on it, but it might help you. I still think you should get a Clymer's manual too, though. You sound like me lots of bikes (and truck/trailer rides home) ago!

BTW, this manual link was on cbrider.com