Help! 81 special sparks once.

[pappysassafrass]

Hey Friends,
Due to an injury, my 81 XS650 Sat partially assembled for 15 years. For the past few months I’ve gotten her ready to go but for one thing….she won’t start. Holding the plug to the engine case produces one fairly strong spark each time I push the starter button, then no spark. Tried another coil with the same result. Checked as many connections and grounds as possible. Anyone have any idea what it could be?
Thanks Pappy

 

[Jim]

Hey Friends,
Due to an injury, my 81 XS650 Sat partially assembled for 15 years. For the past few months I’ve gotten her ready to go but for one thing….she won’t start. Holding the plug to the engine case produces one fairly strong spark each time I push the starter button, then no spark. Tried another coil with the same result. Checked as many connections and grounds as possible. Anyone have any idea what it could be?
Thanks Pappy

I can give ya an educated guess. Weak battery and/or weak connection(s)... corrosion.

Turn the key on and the ignition coil charges. Hit the starter and all the juice goes there, so there's no power left to charge the coil a second time.... until you let off the starter and allow the coil to charge back up.

 

[pappysassafrass]

Thanks for your reply. Makes sense, I do have new battery and have it on a maintainer, checking voltage on the red primary coil wire I’m seeing 11vdc. Could that be it? guess I should follow that wire back.

 

[Jim]

What's the battery in the bike reading right now? Is that the one on the tender?

 

[pappysassafrass]

Yes, I just put it back on…13.6v. To the red coil wire, 12.7

 

[Jim]

That's almost a full volt drop, which is excessive and will need addressing, but that's likely not your problem, as a TCI coil will fire at a lot less than that.
Any chance your meter has a "memory" function... or a lowest voltage button? If it's the coil voltage as I described... and that's still if... you'd want to see what the voltage drops to with the starter engaged.
Can you try kicking it over and see if you get more than one spark?

 

[pappysassafrass]

Battery seems fine, I turned it over a few times and did get an initial spark then several weaker ones. That’s encouraging.

 

[pappysassafrass]

Now back to one spark again But I did get several there with a “full” battery. You’re thinking voltage drop during starting…I’m checking that next. For now, heading in for the night. Thanks for your replies..really appreciate the help. Be back on it after work tomorrow.

 

[Jim]

Look forward to some answers on the above questions then. Meantime...
The TCI system draws somewhere around 4 amps. The charging system draws about 2.5 when the keys turned on. Find the large disconnect for the engine. Should be under the left side cover.... (edit) frame sidecover, not the engine.
Leave the small 3 pin connector hooked up, that's the TCI pickup.

See if saving that 2.5amps gives a better spark.

 

[Vincenthdfan]

Double check all of your grounds, especially for corrosion...notorious for fantom issues like this.

 

[Jan_P]

Are we talking 11 V at the ignition components.

on the red primary coil wire I’m seeing 11vdc.

If so it is to low in my View. Even with a kick start attempt
Have Not worked with the stock TCI but with Points and Boyer.

Needs to come up from 11 V one way or another the sooner the better

 

[pappysassafrass]

Back from the salt mine….thanks for all of your help and support! Assuming this roughly the right place, which is the engine discount? Thanks.

 

[pappysassafrass]

Also, at the battery just now, the voltage dropped from 12.9v to 11 when I cranked the starter. Red wire at the coil was 9.5v

 

[Jan_P]

Yeaa h welll Mr Jim has it there

I can give ya an educated guess. Weak battery and/or weak connection(s)... corrosion.

if you are not certain it is a working battery please take it somewhere to be tested load tested .
Then we take it from there -- Is the battery old..

 

[pappysassafrass]

No load and with load. And battery. New a month ago.

 

[Jan_P]

Assuming disconnected battery ..
Does it no say weak there on the load picture.
I have heard that these new battery's are a bit complicated to load test .Needs to cycle them according to the Vendor here in town they have an equipment that takes a night or so to run the test

Is it charged with a good charger ?

 

[pappysassafrass]

Yeaa h welll Mr Jim has it there

I can give ya an educated guess. Weak battery and/or weak connection(s)... corrosion.

if you are not certain it is a working battery please take it somewhere to be tested load tested .
Then we take it from there -- Is the battery old..

Hey Jan_P - and Mr Jim, I’ve now cleaned every connection I can see and the main ground. I’m going to test that red coil wire at the fuse box and by the coil under load. If there’s a big drop, I’ll be in un-taping the harness and getting a look under there. The sorta sloppy tape job is a bit troublesome. maybe something under the motorcycle a culprit? Like the starter connection. I’ve looked everywhere but where it is. Thanks again. Pappy

 

[pappysassafrass]

Assuming disconnected battery ..
Does it no say weak there on the load picture.
I have heard that these new battery's are a bit complicated to load test .Needs to cycle them according to the Vendor here in town they have an equipment that takes a night or so to run the test

Is it charged with a good charger ?

Yes it was charged well. Could use another overnight.

 

[pappysassafrass]

Assuming disconnected battery ..
Does it no say weak there on the load picture.
I have heard that these new battery's are a bit complicated to load test .Needs to cycle them according to the Vendor here in town they have an equipment that takes a night or so to run the test

Is it charged with a good charger ?

Yes it was charged well. Could use another overnight. It does say close to weak. I’m gonna try my car battery.

 

[Jan_P]

Yes it was charged well. Could use another overnight. It does say close to weak. I’m gonna try my car battery.

Please be careful with the car battery
If there is a short to ground and you connect a stronger power supply it can get hot

Second there is some electronics on the bike .So there is a right way to do it
The car boys please chime in telling how it is done the right way was it minus first and then positive ??? Jump cable connecting