Buzzing from ignition coil and other strange stuff

[xs650newb]

Hey everyone,

Engine is back together. I took the bike for a quick ride yesterday and it ran great with tons of power. There was a strong backfire from the left side exhaust on deceleration, but other than that it was fine. The bike was really hard to start but thats the only complaint.


I tried to start it up again today but it wont start. There is a buzzing coming from the ignition coil when the bike is turned on. The ignition coil is fine because I get the buzzing with two different coils. The bike will sputter every 10 kicks or so and occasionally misfire, causing the kickstart lever to fly upwards.

I tried to see if the plugs were even sparking but when I take out the plug and ground it to the engine it is constantly LIVE. You can feel the voltage while holding the plug. It also is randomly sparking without turning over the engine. I tried this multiple times with the crankshaft at various rotations.

What is going on?

Adam

 

[retiredgentleman]

Oh my! That does sound bizarre. Perhaps an exorcism is in order.

Seriously, if you are getting spark (and buzzing) with just the key on, I would suspect the TCI black box. Maybe you should remove it from the bike, check all connections, and open it up. I remember one guy found water inside his TCI box.

 

[xs650newb]

Damn. Thanks RG. I was thinking I might have to do that.

I had some more discoveries.

First, the buzzing only occurs when a battery charger is connected to the battery.

Second, the bike will sometimes misfire up to 1/2 a second after I am done kicking it over. So it is almost like the spark is coming way too late and unannounced.

Adam

 

[650Skull]

Damn. Thanks RG. I was thinking I might have to do that.

I had some more discoveries.

First, the buzzing only occurs when a battery charger is connected to the battery.

Second, the bike will sometimes misfire up to 1/2 a second after I am done kicking it over. So it is almost like the spark is coming way too late and unannounced.

Adam

First; is the battery disconnected when you have the charger hooked up

Second; check your timing, perfect ankle braker

 

[xs650newb]

My battery remains connected. Why?

The ignition is TCI so I don't think there is anything to check.

I am however, going to recheck the valve clearances and timing chain.

Adam

 

[jayel]

battery charger may not be putting out clean DC voltage rather it's putting out a clipped series of AC pulses hence the buzz, a good charger rectifies and filters the AC pulses a cheap one just clips the positive pulses to imitate true DC voltage

 

[xs650newb]

Ok. Good to know Jayel.

I'll juset let the battery charge and give it another go.

So, like I said in initial post the engine is a fresh rebuild. I took it out once and it ran fine but wouldn't start again. Is it possible the valve clearances have to be re-done after each ride until everything settles done?

Also, what is the spec on cam chain tension? Should the little pin in the tensioner be flush with the surface or should it bob in and out a bit.

Adam

 

[jayel]

Ok. Good to know Jayel.

I'll juset let the battery charge and give it another go.

So, like I said in initial post the engine is a fresh rebuild. I took it out once and it ran fine but wouldn't start again. Is it possible the valve clearances have to be re-done after each ride until everything settles done?

Also, what is the spec on cam chain tension? Should the little pin in the tensioner be flush with the surface or should it bob in and out a bit.

Adam

as close to flush as possible, a little bobbing is normal, yes re-check valves the head bolts will need re-torqued after a few hundred miles and valves re-set then too, after it settles in you should be able to set the valves once a year and cam chain adjust every 1K miles unless you're running it hard... then your milage may vary

 

[xs650newb]

Ok. So my valves and camchain probably don't need a reset already. The last day the bike actually ran it was only run for a 3 or 4 miles.

I'll look into the battery charger.

The whole thing is really weird. The bike won't even fire up with starter fluid. IT just occasionally sputters or misfires (Causing a flying kick start). Compression is good, carbs are clean (shouldn't matter with starting fluid), so it must be electrical I guess.

Adam

 

[retiredgentleman]

My battery remains connected. Why?

The ignition is TCI so I don't think there is anything to check.

I am however, going to recheck the valve clearances and timing chain.

Adam

If you were using a battery charger on the bike, without the battery connected to the bike, that is why you have buzzing. Never use a battery charger, by itself, connected to the bike. Notice its called a "battery" charger not a power supply.

A battery charger actually puts out pulsating DC, which means the DC voltage is going up and down at 120 Hertz frequency. So, any electrical relays, that are used to a nice steady DC voltage will buzz at the 120 Hertz. Your TCI black box would not be happy with that pulsating voltage.

When you connect the battery charger to the battery on the bike, the battery acts as a filter. The 120 Hz pulses of DC are filter into a nice steady DC voltage.

If you were to try to power your bike from an external source, and not use your bike's battery, you would need something called a power supply. A power supply has some of the same components as the battery charger, but the big difference is that it has capacitors and maybe an inductor. A power supply puts out a steady DC voltage.

 

[xs650newb]

Thanks RG. I'm chalking this up to bad valve clearances. I'll give them adjustment sometime soon and see if she kicks over.

Adam