Start up: success, then failure!

[scott s]

1981 XS650.
Today was fire up today. Carbs completely disassembled and rebuilt (even new diaphragms), trimmed plug wires and new caps (plugs looked great, so I left them).
Found out the starter button took a crap. OK, started on about the 5th kick. Ran, idled and revved.
Then died.
I can't get it started now. I tried to check for spark a d CANNOT confirm I have spark. Too hard to do when kicking it over. Tried for an hour to repair/solder starter button and gave up.
I have a simplified wiring harness that I didn't build. Only two fuses. One seems to be for starter, the other for TCI box. Not crazy about the TCI fuse setup, but I can't really keep testing (easily) until I can get the engine turning with the starter.
Guess I'll get a replacement RH switch so I can move forward. I RUINED my ankle kicking an SR500 to death a few years ago. No more kick only bikes for me!
Oh well, it ran for a minute!
I'm open to hints, suggestions and troubleshooting tips!

 

[scott s]

The wires for the iffy 15A fuse are BROWN on one side and a BROWN/WHITE and BROWN on the other side.

The Br/W is for a starter flasher relay, which I don't have. The BROWN seems to be stator/ign. switch, reg./rec., etc.
Lights, neutral light and horn work.
The starter worked when I got the bike. And, like I said, it ran briefly today.

 

[grizld1]

You can easily bypass the starter button while you troubleshoot and wait for a new switch. The button makes the ground contact for the starter solenoid. I don't know how the colors go in your simplified harness, but one of the solenoid wires gets +12V current, and the other is ground; a volt meter will tell you which is which. Crimp a plug (bullet) connector onto each end of a piece of wire and plug one end into the solenoid ground wire. When you touch the other end to a cylinder fin, the starter motor should turn the engine over. To ease the load on the starter, remove and ground both plugs. That should let you look for spark.

Hope you used individual Mikuni carb parts. Some of the stuff that's sold in kits isn't right for the application.

Edit: Where's my brain today? The hot wire on the solenoid is a R/W plug, the ground wire is a Blue/W socket.

 

[scott s]

Genuine Mikuni parts in the carbs.

I made a jumper from the BLUE/WHITE in the headlight bucket to the head. Makes sparks on the head and the starter tries to turn over, but doesn't seem to have enough "oomph" to turn it over easily with the plugs in. After a few attempts, I did get a big POP out of the exhaust, so maybe there is a weak spark?
The battery is supposedly new. It's mounted under the swing arm, so I need to figure out the mounting bolts so I can drop it down and add a pig tail for the charger.
It shows 12.1V. How much voltage is needed to make the TCI fire? If I remove both plugs, will I cause damage to the TCI by turning it over without one of the plugs grounded?

I'm really curious why it kickstarted and ran for a while.....I wonder what happened to cause it to die and not restart. I'll keep plugging away at it.

 

[WideAWAKE]

You got enough gas in the tank?

What does the battery say under load??

 

[gggGary]

Like the bear sez ground both plugs, I keep a spare pair of plugs set up like this.
Some bare copper wire twisted around the bases, long as the copper touches frame or engine you are good to go.

 

[scott s]

You got enough gas in the tank?

What does the battery say under load??

I was running from a fuel bottle.

 

[scott s]

I was able to attach a battery tender pigtail and have it on the charger.
Double checked all the wiring and, as best I can tell, it's all correct. With the RH control hooked back up, I have Hi/Lo beam, neutral light, dash light, tail/brake light.
When I ground the Blue/White wire, I can get the starter to try. It was spinning the engine over pretty easy when I first got the bike home (and before the starter button broke). I have a new RH control on the way.
I also opened the bowl drain on the LH carb and got gas.

I'll let it charge while I wait on the replacement switch and report back.

 

[grizld1]

Battery voltage is not necessarily what's getting to your coils or TCI box. Defective contacts in the key switch and kill switch will cause voltage drop. Try this after you get a charge on the battery. With the key switch on, take a voltage reading at the battery, then at the coil. If there's 1/2V or more difference, check voltage on the power wire out of the key switch (brown in stock harnesses) and the R/W power wire out of the kill switch.

Take a close look at the battery mounting. It's in a vulnerable position if it's mounted under the swingarm. Also it needs to have good damping against road shock and engine vibration. Hard mounted batteries don't tend to last long.

 

[DogBunny]

In your initial post you say it's too hard to confirm spark while kicking. Using exposed grounded plugs like gggGary showed in post #6 it should be easy to confirm spark by kick in a semi-darkened room.

I like TCIs, and have a lot of experience with them. I buy them cheap whenever I can, and then test them on my properly running TCI bike.
I once tested a TCI that worked for exactly one explosion, i.e. it fired exactly once. That one fire sounded great, but it never made a spark again.
The point here is that an old, dormant TCI can work but quickly die.
The weirdest TCI I ever tested was one that made sparks beautifully, but they weren't timed right. Timing was completely random, so the bike would never run.
In your post #6 you say you got a pop. It's kind of a long shot, but maybe your TCI has the same random timing issue. It worked fine, but then the same timing thing that I observed happened to yours. Like I say, a long shot, but always good to try using a known good TCI when you have problems. But first, check for spark.

 

[scott s]

New RH control showed up. I installed it, new plugs and swapped out the 15A fuse.

The starter still doesn't work on the button, and I have no spark.

If I run a jumper/ground wire from the BLUE/WHITE in the headlight bucket, the starter turns. But no spark.

I checked the plug from the starter solenoid to the harness and it looks good. If grounding the wire from the frame turns the starter, doesn't that rule out the solenoid?

I'm going back to study the stock diagram and the simplified diagram I have. Where should I start? I have headlight Hi/Lo, Neutral light, speedo light, tail/brake light. But no spark (and bike ran a few days ago) and no starter from the button, but starter when grounding the Blue/White wire from the main harness, in the headlight bucket.

 

[Jim]

If grounding the wire from the frame turns the starter, doesn't that rule out the solenoid?

Yes. Means the solenoid is working.

 

[scott s]

Yes. Means the solenoid is working.

And that would also mean the wiring harness from the headlight bucket back to to starter/solenoid is good, right?

The RH control is a new reproduction one. I would hope the start button is good. Can I use my multimeter to test just the button?

I still need ideas to test ignition circuit....why I have no spark when the bike kick started and ran/revved fine just a few days ago.

 

[5twins]

Are your handlebars painted? Normally, the starter button grounds through the handlebars over to the left control assembly. The left assembly has a ground wire that runs into the headlight. That ground is shared by the two control assemblies through the handlebars.

 

[Jim]

And that would also mean the wiring harness from the headlight bucket back to to starter/solenoid is good, right?

Yes, looks that way.

The RH control is a new reproduction one. I would hope the start button is good. Can I use my multimeter to test just the button?

Yes, you can check for 12v in on the B/W wire in the RH control. The button just grounds the B/W to energize the solenoid. Ground path is from the right switch housing.... across the handlebar... and into the left housing.... from there a black ground wire goes into the headlight bucket. A bad connection anywhere along that path will cause your prob. Are your handlebars painted? That's a pretty common cause.

 

[Jim]

I still need ideas to test ignition circuit....why I have no spark when the bike kick started and ran/revved fine just a few days ago.

No idea right now. I'd suggest you concentrate on the starter problem first. Kill one bird at a time.

 

[scott s]

Are your handlebars painted? Normally, the starter button grounds through the handlebars over to the left control assembly. The left assembly has a ground wire that runs into the headlight. That ground is shared by the two control assemblies through the handlebars.

They are painted, but the area under the grip/control is sanded down. I'll check to make sure the new control is touching bare metal.
The new control has a 4th prong (black wire) that is a ground, but the plug in the harness doesn't have a matching wire. The previous control was only 3 wires, no BLACK ground wire. The starter turned with the button before the wire broke with this set up.
The LH control operates only the Hi/Lo beam and horn, both of which work.

 

[scott s]

You know, I did reposition the control when I replaced the brake master cylinder. Maybe I need to recheck where it sits and sand off some more paint? I mostly sanded it off to get the throttle tube to move freely and not bind. Maybe I need to do a little more since I moved it?

 

[Jim]

Worth a shot.

 

[5twins]

This little wire clip in the bottom half of the control assembly is what transfers the ground to the bars .....

..... so make sure the paint is removed on the bottom side of the bars where it makes contact.