Need some troubleshooting tips

[kingston73]

Hi all, first post here.  Just picked up an 85 cb650 and rode it home about 45 miles.  It started right up at the sellers house and rode great.  It was leaking from a carb bowl so today I pulled the carbs and replaced all the gaskets.  Reinstall and it wouldn't start and also the headlight and taillight no longer work.  Turn signals work and brake light works.  I'm pretty sure I flooded it because I tried starting with the choke fully closed but the owners manual says to start with choke open.

I'm charging the battery overnight, could that be the cause of no headlight?  Could I have done something when I removed the carbs?  Other things I haven't thought of?  Suggestions welcome, thanks all.

[Bob H]

...it wouldn't start and also the headlight and taillight no longer work.

Did you check all fuses?

...Turn signals work and brake light works.
I'm charging the battery overnight, could that be the cause of no headlight?

A weak battery can cause all kinds of grief - some bikes use all the amperes available to crank the engine but not much left for spark.
So there has to be a good, or freshly charged mediocre battery to eliminate that variable.

It is odd that your turn signals and brake lights work, others don't and "no start".

...started right up at the sellers house and rode great.  It was leaking from a carb bowl so today I pulled the carbs and replaced all the gaskets. 

Did you find EXACTLY where the fuel was coming out of?
I have learned the hard way. A carb leak is not always what it seems.
You suspect the gaskets - but it could be a stuck float bowl (tap the side of carb with handle of screwdriver will sometimes jiggle it back shut).
Basically you want to know if it is coming out of an overflow, or is it an actual "leak" in the bucket.

One clue is to let the carbs fully fill with fuel (put a light vacuum on the petcock). A bad float or float needle will sit there and leak on you, overflowing.
If that doesn't happen, you wait a full minute to ensure the bowls are as full as they are going to be.
Then you shut the petcock OFF, and drain each carb float bowl into a small measuring glass (like a tall shot glass with numbers, I think Pyrex makes one). Use small vacuum line  attached to one carb blown drain nipple.

Each carb should hold about the same amount of fuel. I think the float or it's needle would have to fail before the fuel rose up to the level of the gasket that seals the bowl to the main carb (while at rest).

I struggled with a similar leak that would occur after draining and storing my 1993 model when I had to work out of town (frequently).
After several years of an intermittent leak that would eventually heal, I discovered it was the O-rings at the fuel rails that fit between the carbs.
Once wet with fuel, the O-rings would seal within a week and be OK for the next 6 months.
I replaced them all this year when I re-jetted the carbs and it has not leaked since.

[Gene]

If you have a multimeter, (you can buy them really cheap at Harbor Freight) check the battery voltage without a load, and then while trying to start it. I bet the battery voltage drops real low beause of the load.
I agree that you might have a blown fuse or two. On my 85 650 the fuses are in an awkward place, underneath the instrument cluster, and above the headlight bucket. Just a note: if you do have a blown fuse, there is probably a good reason, I would ask the previous owner,  perhaps he/she knows something.

[kingston73]

I checked and replaced all the fuses, one was blown.  I replaced all the bowl gaskets and sprayed carb cleaner into the Jets and intakes.  I'm currently charging the battery, what should it read one the multimeter?

 Any ideas why the headlight isn't working?  I pulled it out and replaced the bulb. While it was unplugged I checked for voltage.  One wire read 0.16 and the others read 0. 

[Gene]

The battery under no load, fully charged should read aprox 12.5v. Full load, (starting the bike) shouldn't drop much. Typically, a weak or bad batteries voltage will drop to almost  nothing. many autoparts stores have testers  that will test your battery, oftentimes for free.

[kingston73]

Follow up.  I pulled the air filter and squirted some carb cleaner and the bike started and ran a few seconds.  I opened the drain screws on each carb and #2 didn't have any gas but the other 3 were full.

All fuses are good and I even put a new bulb in the headlight and still nothing.  I have no idea where to even start with that.

[Bob H]

I opened the drain screws on each carb and #2 didn't have any gas but the other 3 were full.

If you have a vacuum operated petcock, try VERY LIGHT suction (your mouth) on a tube to petcock to make fuel available. Tap on the side of the carb bowl with the handle of a screwdriver to see if the float seat is just stuck closed, and maybe the floats can can fall down (to open the valve.)
You should see fuel start to come out of the float bowl drain screw, if you open that.

...I even put a new bulb in the headlight and still nothing.  I have no idea where to even start with that.

Your diagnostics show that no electricity is getting to the headlight.
Are you 100% certain the light worked when you bought the bike (recent purchase)?

I have purchased vehicles before that I thought were thoroughly inspected, only to find a shallow dent, rust, something I had missed that was hiding in plain sight.

[Pete in PA]

Headlight is the starter switch.  Hondas have a headlight interupt as you push the starter switch the headlight turns off so the starter gets full voltage.

Disassemble the right handlebar switch group and clean the contacts.

[kingston73]

Following up.  I opened up and cleaned the starter switch on the right handlebar.  I pulled out the headlight and cleaned all the connections inside.  I cleaned the 4 fuses and made sure they were all good.  Multimeter says there are 12 volts to the top fuse connection and zero volts to the bottom.  With the bulb unplugged there is only 0.15 volts to both the blue wire and the green wire of the headlight connector.  So now what?

[Bob H]

Multimeter says there are 12 volts to the top fuse connection and zero volts to the bottom.

I don't understand this.
You mean the same fuse... top and bottom connection to a single fuse?
If so, and you get 12 volts on one end but none on the other, the fuse is blown or not getting continuity (like not fully inserted, corroded, etc.)

[kingston73]

I wanted to know if the fuses had power, and I probably didn't do this correctly but I removed the fuse and used the multimeter + inserted into the top connector

[mollusc]

Without the fuse in there, you won't get any voltage at the bottom terminal.  Do you get voltage at the bottom terminal with the fuse installed?

[kingston73]

The headlight bottom terminal has low voltage, it wasn't exactly zero

[Bob H]

The headlight bottom terminal has low voltage, it wasn't exactly zero

No offense, but that is kind of clear as mud.
A fuse has 2 points of contact, previous post mentioned multimeter measure with fuse removed...

The bottom fuse terminal with fuse removed is irrelevant, doesn't matter if it wasn't exactly zero.

The important thing is confirming continuity through the fuse, and if that voltage is not present at the headlight socket then you track down where there is an opening in the circuit (assuming fuses aren't blowing due to a short)

[Bob H]

it wasn't exactly zero

Another bit of data is that a digital multimeter will often show odd small amounts that fluctuate when the leads aren't connected to anything (or in your case you are trying to read "voltage" with no fuse connected to lower fuse terminal)

A few years ago I decided to bite the bullet and purchase an expensive multimeter, as my ancient "Radio Shack" meter and a newer Harbor Freight garbage-meter were untrustworthy.

I noticed the numbers jumping around before connecting the leads to a battery, or checking for continuity / resistance.

The following video explains this phenomena. I would like to also add that the newer, better quality meters are "auto ranging". The meter can detect the range of voltage, the range of resistance being fed into it and will display the reading in the appropriate range. My older meters require you to select various ranges.

As the guy says in this video, when the leads are not connected it is hunting for MILIVOLTS (Thousandth of a Volt) as the "ranging" meter doesn't detect much going on and defaults to a very sensitive range of measurement.