Topic: 1975 CB550K won't start!

[itzjoker]

Bought a non-running CB550K.

I rebuilt the carbs, bought new battery, and replaced the spark plugs and caps so far.

When I use the electric start I can hear it turn over but it does not want to start at all with choke on or off.

What is the next thing I should look at? If it's getting spark? If not replace points & condensers?

I tried checking for spark but now the motorcycle does nothing when I hit the electric start, drained the battery?

[Scott S]

 Charge the battery.

 While you're waiting, adjust the valves, set the points, static time it. Then check for spark.
 What do the plugs look like now? Wet or dry?

[itzjoker]

Charged the battery and tested it, good to go.

Put it back on the motorcycle and now it's not turning over. Lights turn on but does nothing when I try electric start. Burnt out starter?

Also, does it matter if I adjust valves or static time it first? Plugs are dry.

[itzjoker]

No noise now. It was turning over and cranking before but no start. I’m guessing I burnt out the starter.

[TwoTired]

Any desire for electrical troubleshooting?  Or, just a parts changer guy?

Have a voltmeter?  Limbs and fingers to manipulate it?

Maybe you could post a picture of the bike.  So, we can press our foreheads to the screen and mind-visualize the exact issue the bike has?

Nice day outside.  Gonna go ride now...

[itzjoker]

Shorted the solenoid and starter is good. Now I need to figure out why electric start is not working all of a sudden. I know the Kill switch is working because I can hear a faint click and dim in the lights when switched to Run. Neutral light on, kick stand up. Maybe start button is defective? 

Gonna follow this thread for spark issue once I set my point gap and timing.

http://forums.sohc4.net/index.php/topic,107498.50.html

[itzjoker]

Point gap set and static timing set
Getting 12V to coils at black/white wire
Getting 12V to blue/yellow wires when points are separated
Getting spark at points and plugs
Starter turns when solenoid is shorted

Traced the yellow/red wire coming out of solenoid to the male end and connected that directly to battery positive terminal, nothing happens.
According to that, is it safe to say that my solenoid is bad and not my starter switch?
(If the start button sends +12V to solenoid for my year, which I'm not sure of)

[Bankerdanny]

Yes the starter button would send 12v to the solenoid. Since touching the yellow/red wire directly to the + terminal on the battery didn't cause it to turn over as it should I would say you have a bad solenoid.

However, two other things to check: (1) do you have a clutch lever safety switch or a side stand safety switch. (1) keeps the bike from turning over unless the lever is pulled in and (2) does the same, but requires the side stand to be up.

To check for the clutch lever switch just look for a single wire coming out of the lever. To check for the side stand well, get down and look under the bike for a switch at the stand.

My 750 had a similar symptom, pushing the button dimmed the lights but didn't turn over the engine. However the yellow/orange wire test did, so I knew the solenoid was fine and the starter button was the issue.

[itzjoker]

The side kickstand has been up, bike has been on center stand and it was cranking over fine without pulling in lever (but in neutral). Only thing I did was cranked the bike away with the starter button trying to get it to start and it finally just stopped kicking over. I’ll go ahead and replace the solenoid.

Hopefully it starts with the kickstart now that timing is correct and I know I’m getting spark.

[TwoTired]

The 75 Cb550K has two wires to enable the solenoid.  One is black, which is switched 12V  (it should come on when the key switch is on).  The other is Y/R which must supply a ground to enable the solenoid (from the start button).  Jumping the Y/R wire to the POS post will do nothing, jumping the Y/R on the NEG post should enable the starter solenoid, provided the black wire does indeed have +12v on it.

Your current testing has not proved the solenoid has failed.

Please refer to the wire diagrams for the bike in question, as Honda changed the solenoid wiring operation through the years of production.  The 75 model K still has a starting motor safety unit which supplies that ground to the start button based on neutral switch and clutch switch positions.

Cheers,

[itzjoker]

So I grounded the male fitting and nothing. But when I ground the female fitting the starter motor turned. So solenoid is okay?

Tried using electric start that way to start the bike, no luck. After kicking like 10 times heard a giant bang, thought I blew something up. Kicked a couple more times while giving it gas and she finally started up! Thanks for all the help fellas. Will worry about the electric start later. Now it’s time to get her to idle without throttle.

[Bankerdanny]

While the engine is warming up you will need to either use the throttle to keep it running or reach down and turn the idle control knob in to raise the idle. The early K bikes don't have a fast idle cam like the 77-78's do.

[TwoTired]

So I grounded the male fitting and nothing. But when I ground the female fitting the starter motor turned. So solenoid is okay?

The solenoid activates when 12V  and ground is applied to the small posts.  If you can do that and the starter engages, then the solenoid and starter are okay.  Now you will need to figure out why your bike won't apply 12V and ground to the solenoid.

As I said, your bikes bar button supplies the ground which is routed from the starting safety unit.  That little box has logic in it to provide that ground when either the bike is in neutral or the clutch is disengaged.  It is quite startling to gave the bike jump forward when the button is pushed, hence the safety unit.

You've probably noticed the kick start won't work unless the clutch is engaged.  Best be in neutral for that.   But, if you stall it going away from a stop, it is quite handy to just pull in the clutch and hit the start button to be your way with minimum delay.  Other drivers will otherwise drive around you within minimum distance, usually cursing at you.


As mentioned, a cold engine won't idle without some added throttle  (poor fuel atomization).  After the engine warms it should settle into 1000-1100 rpm, adjusted with the big idle knob.


Cheers,