Topic: non starting 79 650

[IainC]

Battery seems weak, but there IS spark. While connected to a 10A charger when you hit the starter button the voltage drops to ~8.7V but bike turns over well, and as stated there IS spark.

Just took the carbs out and used almost a full can of carb clean on them. Carbs appear to be getting fuel fine.

Bike had been running until stored last winter.

Suggestions?

[OldSchool_IsCool]

Don't use more than a 2-amp battery tender, the kind that stops charging when full.  Let it charge over night.

Was the bike wintered with gas in the carbs?  if yes, you will prolly need to crack the carbs open and clean it thuroghly (jets, emulshion tubes, passages, etc) then bench sync (flashlight method recommended).  Carb cleaner by itself isn't guna do it.

You may be able to get it to fire up on carb cleaner just to verify timing.  Not recommended for sustained running!

[IainC]

I'm leaning towards a problem with the battery. I had the carbs off last year, cleaned them throughly, as well as synced them properly (with a carb tuning tool). I honestly can't remember what we did winterizing the bike, but i'm sure i would have drained the carbs to save myself tearing them apart again this year.

Does anyone here know what kind of voltages I should expect when turning the motor over? I have had it on a 2amp charger for over night, and all the lights and whatnot seem to come on, the starter seems to be trying, but I just can't get any combustion. Plugs probably need to be replaced, and I'll take care of them when I have the cash for it, but untill then, I figured I would at least be able to get it running. Best I can guess is the battery just isn't giving the plugs enough juice to get a hot enough spark.

[Hush]

Ah the dreaded 79 650 charging issue, sorry mate been there done that but at least you can gain from our lessons learned.
If the motor is turning over when the button is pushed then your battery is fine, something else is holding it back.
Old plugs might be dirty but they won't stop it firing up either.
You should get about 14 volts from your battery, put the lights on and it will dip to maybe 13.
I chased this gremlin through my whole system for months, bike ran well enough but even after riding all day once I turned it off it didn't have the power to start again, leave it for a while and she starts.
I used a borrowed stator, wasn't that.....a borrowed regulator/rectifier, wasn't that.....a borrowed rotor...jackpot.
My bike starts first time everytime now and holds charge for weeks when I leave it.
Not saying this is your problem but it turned out to be mine, our 79 650's have an aging charging system (30 years old  ) so adding bits is gonna have to happen.
I got a second hand rotor for $50.

[Hush]

Just looked back on my rebuild thread and found the measurements I took when testing the battery charge.

Bike at rest 12.93 volts
       at idle  13.40v
at 2500rpm 13.30v
at 5000rpm 13.50v
at 5000rpm 13.30v with headlight on fullbeam.

AND BELOW IS AFTER I CHANGED THE ROTOR FOR A BORROWED ONE.
Fired straight up no pause no hint of not wanting to run, re took the battery readings, at rest 13.29 volts, took her up to 5000 and the voltage climbed to 14.39.

[Pinhead]

Will it start with a hit of starting fluid?

[Buber]

Hmm, starting, after all is simple:
1. fuel - should be there. Turn engine a bit without ignition and check the plug if its wet from fuel . Should be.
2. Ignition - there should be spark on the spark plug. Now this is tricky, as there are sparks and sparks, but a spark is good for the start.
3. order of ignition cables - I know, it's obvious, but on the other hand it happens... check that cylinders have right cables on them.

And if it all checks, then it must start, at least cough.

[martino1972]

voltage dropping to 8.7v is not enough juice to spark.......your sparplugs might spark when you got them out of the engine but under compression I bet they don't.........

how old is that battery ...?

[Jay B]

voltage dropping to 8.7v is not enough juice to spark.......your sparplugs might spark when you got them out of the engine but under compression I bet they don't.........

how old is that battery ...?

I just put a Dyna 2000 ignition kit in my brothers '79 dohc 750 and cured all spark woes.(same basic ignition as your 650) Those ignitions were pretty crude affairs, and that low of voltage deifinitly won't fire them. That bike would start, but wouldn't rev over 6k rpm even under no load, in neutral. Make sure you have a decent charging system, you should get over 14 volts like Hush said.

[IainC]

I think I'll have to pick up a new battery and give that a shot. Not sure the age of the battery as I got it with the bike, but I had to refill the water in it for the second time myself, so odds are its at the end of its life span. Hopefully thats the only problem.

Only other problem I've noticed, is right under the seat, there is a small black box, can't figure out what it does, but it seems that some plastic on it has melted and dripped down. Not sure exactly what it is, but its some part of the electrical system. Any ideas?

[Hush]

That's your regulator/rectifier system, when they get too hot they melt the surrounding black stuff they are protected in, it's like tar.
The fact that you had to refill your battery tells me there is something very wrong with your charging system, I've got a new battery in my bike and same thing happened, think they must boil or something.
Anyhow after much investigation I replaced the rotor and all is good, some of the other 650 guys have had the same trouble, one guy is on his 3rd rotor.....they must be all a bit buggered by now at 30 years old.
Don't worry too much about that black stuff melting down under your seat, once you cure your charging system problems it will stop doing that, there's some capacitors etc in there.

[MJL]

Don't use more than a 2-amp battery tender, the kind that stops charging when full.  Let it charge over night.

Was the bike wintered with gas in the carbs?  if yes, you will prolly need to crack the carbs open and clean it thuroghly (jets, emulshion tubes, passages, etc) then bench sync (flashlight method recommended).  Carb cleaner by itself isn't guna do it.

You may be able to get it to fire up on carb cleaner just to verify timing.  Not recommended for sustained running!

I've had engines running on way worse than 8 month old gas.  I doubt it's gas, more like the battery.

I've had to buy a new battery at least every other year, I recommend borrowing a known good battery and see if it starts with that. 8.7 volts might make a spark, but not enough to light the fires.

[IainC]

hmm... so you think it may be the charging system. One of my friends has her engine in pieces right now, so I think i'll borrow her battery and give that a shot. But as for the rest of the charging system, what would you recommend as first steps in making sure its running fine? I doubt I'll be able to start testing it untill the bike runs again, but once it is running, any particular points I should take my multimeter too?

As a side note, I have to say this forum keeps growing and getting better and better, a couple years ago I'd post and get a handful of replys, now it seems within no time I've racked up a couple pages worth of replys and plenty of great advise. Thanks again everyone. The community for these old bikes alone will have me rebuilding them for years to come.

[Hush]

Just from past experience I'd take a punt on the rotor mate, if you can borrow one and chaarge your battery up then see if the bike runs....my bet is it will.
If you want to test using your multimetre check out Kits' thread on her 650, she has a diagram on where to test, basically it's the yellow wires from the stator, the plug goes into the regulator/rectifier box, just unplug it and test from yellow to yellow in the ohms range to make sure the stator isn't stuffed.
To test the rotor (although mine tested fine) you use the ohms range again to check to see if the two rings are contacting each other, they shouldn't and the reading should be very low.
I'll see if I can find the test diagram for you.

[the technological J]

this could be stupid advice but i hook up the jumper cables to a car... it keeps it turning.. then u got plenty of time to play with the choke and thethrottle.. if its a dumb idea im sure i'll hear about it

[Hush]

OK hope this works.  http://www.electrosport.com/technical-resources/library/diagnosis/pdf/fault-finding-diagram.pdf

[OldSchool_IsCool]

When you do get 'er running, use your multi-meter to check the voltage at the battery.  Rev the engine.  If the voltage goes above 14.5, then your regulator isn't working and the high voltage is cooking your battery (explaining the loss of acid).

[razor02097]

If you do run it with jumper cables make sure the car is OFF... the charging rate in a car is very high and can make a very dangerous situation.

[cb650]

Hush the black goo boxes under the seat are the ignitor boxes. The reg/rect (2 big wire plugs) is the big heat sink looking thing on the left side under the cover.  Not sure where it is on the Z. 
Yes if you use a car be sure it isnt running and dont just keep cranking on it.  Let the starter rest.  Are the plugs even wet?

[tlbranth]

gabriel - that was my suggestion too. Jump battery from a car. That eliminates the battery as the source of the problem. Next, pull one or two plugs and squirt a small amount of gas (preferably mixed with 2-stroke oil) into the cylinder. Give it a try. If you get a temporary start, fuel problem. If not, ignition problem. Use 2-stroke mix to avoid washing lube off the cylinder walls in case it is an ignition problem. Good luck

[IainC]

If its a melting ignitor box, how is that going to affect how the bike functions? Could it be a source of the problem? Unfortunately I haven't had a chance to try out any of the others suggestions yet, but when I do I at least have a few more ideas.

[Hush]

ARRGH CB650 of course you are right, I'm trying to do this from memory, sorry IainC those ARE your ignitor thingyies but from what I've seen on this site as long as they are not fried inside they will still work with that goo removed.
Using a car to jump start is fine, the whole system is 12 volts anyway just as others have said don't crank the starter motor to death.
I prefer when jump starting to put the negative jumper cable onto a really good earth like the engine mounting bolt.
If you follow that test diagram I posted you can have hours of fun finding your faults.

[MikeB]

If its a melting ignitor box, how is that going to affect how the bike functions? Could it be a source of the problem? Unfortunately I haven't had a chance to try out any of the others suggestions yet, but when I do I at least have a few more ideas.

If its the ignitors there should be two of them
if there gone you would not get any spark
did you check spark at all 4 plugs ?

[Spanner 1]

Nothin' wrong I think except need a new battery in that bike.......your present one will not operate the bike.....

[Frankenkit]

well he can't get it started.  I'd start with a new battery (or get this one charged and load tested at the local shop) and then look into your wiring/charging system.  Buy a multimeter at harbor freight or sears and follow that electrosport diagram, but be warned: 1) 650 rotors can fail and still provide seemingly good resistance at the sliprings. 2) Some aftermarket regulator/rectifiers exceed 13.8v.  Mine from oregonmotorcycleparts maxes out at 14.7.

[Hush]

Is he still stuck Kit?

[Frankenkit]

oops. dunno.  accidentally dug up a zombie thread.