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pinbill

New to me 73 Alpina 350: No Spark

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Hello,

I just bought my first Bultaco its a 1973 Alpina 350. I usually don't buy non running bikes, but this one was in such good shape I went for it. The PO was an older guy who was the second owner. The first owner was his long term friend. I remember seeing spark when I bought it and the compression seemed good when kicking it over. I rebuilt the carb and was hoping to hear it run, but now it doesn't spark. I attached some pictures, because I know you guys like pictures. It has a headlight, taillight, brake light, and kill switch. I don't know if they are stock or aftermarket.

My first move was to clean and tighten the wires going to the wire connector block. The white wire going up to the headlight was loose. It looked like it was grounded to the screw holding the wire block in place. To narrow things down, I disconnected the green wire to the headlight, the yellow wire to the headlight, and the grey wire going to the kill switch. Then I cleaned the wire connector block.

At this point I got a lit test light on the green wire that goes to the motor. I also got a light on the black wire to the motor but only with it disconnected from the terminal block. When I connect the black wire from the motor to the block with the coil connected the test light doesn't go on. I couldn't get a light out of the yellow wire.

I put my ohm meter on the coil. It was reading steady 3.6 from the plug wire. The measurements were jumpy from the black wire to ground but it would settle in at 1.1. There is no spark plug boot. The PO jammed some wire in the spark plug and wrapped it around the plug. Maybe that killed the coil. Who knows?

I read about the condenser getting hot and going out so I decided to check the points, condenser, and magneto. It turns out the PO had a spare condenser and magneto puller. Maybe he monkeyed around with it at some point. The insulation was a bit frayed on all the wires under the side cover. The yellow wire was a total mess (no wonder it didn't work). I changed the condenser, taped up the frayed wires the best I could, and put it back together.

The test light is way brighter from the green and black wires. I am getting a faint light from the yellow wire. I know the black wire is the key to getting this running but I can only get the light when the coil wire is disconnected from the connection box. I read that the green wire is supposed to go to ground the coil nut. When I touched the green wire to ground and it sparked.

I am thinking the coil is shorted. Does anyone know what type of coil I can put in it?

IMG_20180708_145703346.jpg

IMG_20180712_142318107.jpg

Edited by pinbill

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Black wire  from magneto goes to the ignition coil. If the condenser is frame mounted,black would go to the condenser and then from there to the ignition coil terminal. Green must go to ground in order to spark.  Don’t replace the coil it’s not the problem.  Wiring diagrams for that bike are plentiful on the net.  

Steve 

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The yellow and red wires are for lighting only, suggest red to power horn and yellow for lights including stop light. As Stevem75 says green to a good earth and Black is ignition live coming from low tension coil in magneto and going to condenser and then travelling up to chocolate box connector near headstock, this then is connected to the low tension side of high tension coil under tank mounted to frame. It’s a popular modification to move the condenser from inside magneto to under frame near to ht coil as it is easier to get at if trouble happens.👍🙂

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Hey Guys,

Thanks for the responses. I did some more testing this morning.

The green wire from the engine goes from the connector block and grounds out at a resistor near the air box. The ground tested good, but the green wire is getting power all the way from the motor, to connector box, and to the resistor. If its a ground wire should it have power?

When I test the black wire at the connector block with a test light, it doesn't have power when the coil wire is attached to the connector block. If I unplug the coil wire from the connector box the black wire from the engine will light up.

Motorcycle electrics are not my strong point. It seems like the coil has a short because the black wire loses power when the coil is hooked up.

Bill

 

 

 

 

Edited by pinbill

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I think your original post said when you grounded the green you had spark.  Problem solved.  Yes the green does terminate at the resistor ground.  This is normal. It could also be grounded to the ignition coil bracket.  Both ways will work  

I’m not sure I understand how you’re using a test light to diagnose.  This would mean you have some sort of powered  light that will illuminate when you have a circuit.  This type of test will prove nothing with this system 

The black wire from the magneto goes to the ignition coil.  The green wire goes to ground.  The green wire grounds the magneto..... sort of.   It’s function is to activate the rear brake light if so fitted. ( through the resistor) If it isn’t fitted or you’re not using the brake light then ground the green wire !!

please do not jump to “it must be the coil” conclusion.  I’ll say it again.   It’s not the coil. !

Check simple things first.  Known good plug.  Known good plug cap.   Clean electrical connections. Disconnect all peripheral components except the black and green wires.   Check for spark.  If it doesn’t spark with black to coil and green to ground.  Then un ground the green wire and leave it connected to nothing.   Check for spark again. If still nothing then make sure points are opening completely to enable the circuit to break.  

This problem Won’t  be more than dirty points, bad/broken wire or connection, or bad plug.  Highly highly unlikely that the low tension coil or ignition coil are the issue 

 

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One other thing it could be is the end of the high tension lead where the spark plug cap screws on. This often gets very corroded and won`t let much current through. So just take the plug cal off and trim the spark lead a half an inch or 10 mm. As has been said the green is the ground and the black goes to the coil.

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hello, 

 ive been running a few old bikes lately.  the first thing I want to mention is the point style ignition cannot use any type of resister in the sparkplug or plug cap. so don't make the mistake of purchasing a 5k resister sparkplug cap or modern iridium plug with a 5k resister built in, its critical to use the correct non resister sparkplug and cap or the bike will never run right when u get it running... points are just a connection to ground when they are closed, ive had nearly new points that when they sit too long the tarnish on the point pads prohibits the connection to ground and the voltage can not build up in the primary side of the ignition coil. if the points don't actually connect to ground because of tarnish on the pads u will never make any voltage. . I would find a wiring diagram for the bike, wire it exactly as shown, install new points so u know u are getting the connection to ground, set the point gap to the wider side of the specs so u get adequate dwell providing a good spark. when the points are closed the coil in the motor creates voltage that goes to the primary side of the sparkplug coil, when the points open the collapsing voltage field has no choice but to go out thru the secondary side of the coil that ups the voltage by winding ratio and sends it to the plug causing the spark. u need adequate dwell to give the spark time to happen before the points close again building up the primary field before disconnecting and sending the voltage to the plug again. the capacitor is not a critical component to running, its only function is to reduce the arc at the points and extend the life of the points, the bike will run wthout the capacitor but the points will have a shortened life from arc pitting.  hope this info helps.  capacitor and condenser the same part my bad reference

Edited by maxwell smart

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As your bike appears to be largely original spec. (surprisingly so, in fact) you may find this of interest :

5b49e3631b3eb_Bultacoacwiringdiagram.jpg.05ed2ab9286e8fa25ff30741bd930a93.jpg

Hope this helps.

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Hey Guys,

That is a lot of good information. Thanks for the diagram.I looked a bit and couldn't find one that looked right. Most were in Spanish or German. haha.

In the first post I said the green wire was sparking when it was grounded. That was confusing, sorry. I meant that the green wire itself was sparking when I touched it to the frame. Not that the spark plug was sparking. Sorry for the confusion. I was surprised that a ground wire would have power running to it. I will remove it from the connector block and ground it directly to the frame at the coil.

I was using the test light to verify that the magneto was at least making some power on each of the wires. I understand now that it doesn't apply if the points are not grounding properly.

I watched a few videos about cleaning and setting the points yesterday. This is my first time trying to diagnose a ignition problem with a points system. I feel have a good understanding now of how the system works. I will have plenty of time to dig into it this afternoon. I am going to get a new plug and spark plug boot today as well.

Thanks again for the help,

Bill

 

 

 

 

 

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bill,

 take a look around the internet at articles focusing on the theory and principles of whats happening in a points style ignition, I think u will find it a good read . my point is u can gain an understanding of the components of a typical system and once u see what each piece does and when and why u can apply that to getting your bike right . the key is to understand what happens in one cycle of the engine to create one single spark . then it all gets much clearer the goal of each connection and item. and I notice the terminal block on the bike I believe only connects across left to right not top to bottom, so your green wires are not connected together as currently configured. 

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Pinball, one thing often overlooked is a poor or non existent earth contact between the motor casings and the frame If a machine has been standing a long time then rust may be present on the engine mounting tabs. In just 20 minutes make up a fairly thick wire with a ring terminal each end. One end under a 6 mm nut at the rear of the engine casing, kickstart side, the other end to any handy bolt on the frame. Make sure your connections are super clean. That’s it ! Poor earths cause no end of weird effects, this bypasses a common one on older bikes. When everything is running as it should, just make a neater, tidier job of this good earth. Hope this helps........

 

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We've got spark!!!! It runs too!!!!

I got it to fire up and idle. The top end sounds real good. No piston slap or anything like that.

Thank you guys so much for helping me with this. I really didn't know how a magneto ignition system worked before this. I have learned a lot. That wiring diagram looks like the right one. Thanks again.

I am going to get some non ethanol gas, change the oils in the crankcase, and take it for a ride. I am going to get the lighting going too. I don't have it hooked up yet, but the yellow wire was putting out 4.5 so I think I can get it working.

Is the brake light a stock item or was it aftermarket?  It is missing the lens so I may use a bit of red tape to start. Does anyone have a lens laying around their shop?

 

 

 

IMG_20180714_120610565.jpg

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Great news what solved the issue when I might ask please.

If the rear light is original try:

Hughs Bultaco in USA,

Orlando Calonder in Switzerland, or

Hansjörg Pfahler in Germany,

for a spare lens, otherwise try in Spain:

Ivan Cirre cimes in my mind here.

 

 

 

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