750 sf ignition problem

Blackwolf said:
I feel your pain. I have the same problem except non-fire on the right side. Replaced coil, plug wires and plug... no difference. I bought 2 new condensers thinking one might be bad. Went to replace them and guess what, they are riveted in place along with the cam wiper.
I will have to remove everything, take it to work, grind off the rivets and probably braze up the oversize holes, re-drill and then tap the holes. Then screw in the new condensers. Even then it's a crap shoot that it works and fixes my problem. I had to wait over a month to get the parts so you can say I am a bit frustrated.
If all works well, it might.....might work but I have my doubts. This bike ran fine when I bought it years ago and when I trucked it home, it never ran on two cylinders again. Luckily I own a couples of BMW's. Most reliable motorcycle on earth! The Laverda isn't a bike I would take more than walking distance from home. Just like a hot woman, nice to look at but she'll take your money and stab you in the back.
I wish I could find somebody to work on it, or to buy it. I hate the thing.
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If you are fault finding, you can simply wire in your new condensers anywhere in the negative side between the points and the coil, with the body of the condenser earthed. The SF ignition is as simple as any ignition can get, and fault finding is as easy as ensuring that 12 volts goes to the correct side of each HT coil and that the points can earth out the negative side of each coil. Your contact points on the breakers must be good and the gap set. You can use jumper leads to eliminate all of the bikes wiring and most of it can be checked with a multi meter. I have seen voltage drop to the HT coil due to bad contact through the original fuse box cause SF to run on one cylinder. Are you spinning the motor over with the plugs out checking spark and there is nothing on the RHS? You can try swapping any components side to side to find the cause of the problem.
 
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Tippie said:
If you are fault finding, you can simply wire in your new condensers anywhere in the negative side between the points and the coil, with the body of the condenser earthed. The SF ignition is as simple as any ignition can get, and fault finding is as easy as ensuring that 12 volts goes to the correct side of each HT coil and that the points can earth out the negative side of each coil. Your contact points on the breakers must be good and the gap set. You can use jumper leads to eliminate all of the bikes wiring and most of it can be checked with a multi meter. I have seen voltage drop to the HT coil due to bad contact through the original fuse box cause SF to run on one cylinder. Are you spinning the motor over with the plugs out checking spark and there is nothing on the RHS? You can try swapping any components side to side to find the cause of the problem.
Click to expand...
First off, I know absolutely Nothing about ignitions systems other than just replacing parts until it starts working. Besides, I have been shocked with high voltage enough times to let someone else do the dirty work. I did have a car once many years ago that just stopped running after I ran thru a dip in the road. I pushed that thing well over a mile before a friend gave me a ride home. He said it was probably the condenser and low and behold it was. Same thing with this bike. It was working fine when I loaded it in my truck and after some bumpy roads on the way home, it didn't run on the right cylinder so I assume it was also a condenser. Since getting the parts take so long, I got a new coil, plugs, plug wires and the condensers all at once. I replaced everything except the condensers, but they don't just "Drop In".
If it's a ground problem or a loss of voltage somewhere there is no way I have the skills or tools to diagnose it. I just need to find a Laverda expert which is like finding a needle in a haystack. I will have to modify my points plate to accept the condensers which I am capable of doing. I hope it works, I am running out of options.
Wish me luck.
 
Blackwolf said:
I feel your pain. I have the same problem except non-fire on the right side. Replaced coil, plug wires and plug... no difference. I bought 2 new condensers thinking one might be bad. Went to replace them and guess what, they are riveted in place along with the cam wiper.
I will have to remove everything, take it to work, grind off the rivets and probably braze up the oversize holes, re-drill and then tap the holes. Then screw in the new condensers. Even then it's a crap shoot that it works and fixes my problem. I had to wait over a month to get the parts so you can say I am a bit frustrated.
If all works well, it might.....might work but I have my doubts. This bike ran fine when I bought it years ago and when I trucked it home, it never ran on two cylinders again. Luckily I own a couples of BMW's. Most reliable motorcycle on earth! The Laverda isn't a bike I would take more than walking distance from home. Just like a hot woman, nice to look at but she'll take your money and stab you in the back.
I wish I could find somebody to work on it, or to buy it. I hate the thing.
Click to expand...
You don't tap the holes for the condensers, you use screws with nuts behind the back plate.
Better to do it as preventive maintenance anyway since the rivets work loose over time and you're then chasing a misfire.

I went touring nearly two months this summer on my SF. Not only is it ultra reliable but you can sort almost any problem by the side of the road. I had the choice between a modern Aprilia and the SF, I took the SF and am planning to take my 1970 S next summer.

Paul
 
If I was going down the path of replacing condensers I would co-locate them with the coils, I suspect it would be a cooler location than the points assembly. Hence more sympathetic to a long reliable life (for the condensers).

Cheers,
bazzee
 
Eventually traced the problem to the Boyer ignition, was immediately going to 70 degree advance, and wouldn't change from that position, no matter what revs, (when I managed to rev it).
Got a Ignitech ignition from Keith Nairn, which he had pre programmed, with new duel output coil, leads and plugs. Immediately the running was transformed, with no ignition problems, was able to identify on the first ride, that the only running issue remaining was a slight hesitation at 1/3 throttle, caused by slightly too big pilot jets of 60, replaced with 55, perfect!
Mind, it's in bits again now, clutch not working quite right, found someone had changed the clutch push rod ball bearings with smaller ones, also slight wear on the rods, (possibly due to the small bearings) So decided to put new clutch in and springs whist it is in bits, partly due to how expensive the crankcase gaskets are and not wanting to take it apart again too soon.
 
Lyndoneil said:
Eventually traced the problem to the Boyer ignition, was immediately going to 70 degree advance, and wouldn't change from that position, no matter what revs, (when I managed to rev it).
Got a Ignitech ignition from Keith Nairn, which he had pre programmed, with new duel output coil, leads and plugs. Immediately the running was transformed, with no ignition problems, was able to identify on the first ride, that the only running issue remaining was a slight hesitation at 1/3 throttle, caused by slightly too big pilot jets of 60, replaced with 55, perfect!
Mind, it's in bits again now, clutch not working quite right, found someone had changed the clutch push rod ball bearings with smaller ones, also slight wear on the rods, (possibly due to the small bearings) So decided to put new clutch in and springs whist it is in bits, partly due to how expensive the crankcase gaskets are and not wanting to take it apart again t
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Put points on it for God's sake.

Paul
 
Blackwolf, if you are interested to learn about these simple ignition systems, there are likely countless instructional videos on youtube, as well as written literature. There is absolutely no need to risk getting shocked, you can ground a spark plug, and with the points open/ignition on, use a screwdriver to earth the "live" side of the contact breaker, and un-earth it and see if you get a spark at the plug. A symptom of a stuffed condenser is that it will spark huge at the points themselves because the condenser isn't storing the charge as it is supposed to. To own any bike this old really does require some handy mechanical skills, even BMW do in fact require service and repair, and unless you have access to some ageing "expert" there is very little chance of any modern bike shop being of the least help. A mate with an older BMW GS told me that his friend is the workshop manager of one of Oslo's main MC dealers, and he told him that none of his mechanics would have a clue on servicing that BMW, let alone fixing it.
 
Any old bike that has been messed around with is unreliable.
Laverda, along with Moto Guzzi, produced some of the most reliable bikes ever.

Paul
 
Right now it's a parts availability issue if I were to replace the points too, which I feel I may have to do when I get the condensers out. Who knows where I can get them. I opened up the parts catalog and the ones shown for my bike look nothing like the ones I have so back to drilling and possibly tapping holes (in the correct location). I don't know how specific they are or if any set will work as long as the fit. I really don't know much about electronic functions. They may be hanging on the shelves in Australia or Tasmania, but here in the US they are as scarce as Thylacines.
 
If your points aren't badly pitted or worn thin, no need to change them.
Original points are to all intents and purposes unobtainable. You need to adapt points from other sources.
Andy Wagner at Laverdaparadies sells points but without doubt others on here know alternative sources.

Paul
 
Paul Marx said:
Any old bike that has been messed around with is unreliable.
Laverda, along with Moto Guzzi, produced some of the most reliable bikes ever.

Paul
Click to expand...
My bike is all original and has never been messed with. I bet the ignition cover hasn't been opened since Guido first put the screws in. It looks like it has been in a time capsule for 47 years. It just decided it was time to stop producing voltage on one side. I would like to hope it's a reliable as you say. Once I get the condensers in I will see.
 
bazzee said:
If I was going down the path of replacing condensers I would co-locate them with the coils, I suspect it would be a cooler location than the points assembly. Hence more sympathetic to a long reliable life (for the condensers).

Cheers,
bazzee
Click to expand...
How do you go about re-locating the condensers? Do you just attach the wire to the coil? That seems way to easy. There must be more to it than that. I am all for simplicity and reliability.
 
Lyndoneil said:
Eventually traced the problem to the Boyer ignition, was immediately going to 70 degree advance, and wouldn't change from that position, no matter what revs, (when I managed to rev it).
Click to expand...
Sounds as if you had the polarity of the pickups wrong..

Marnix
 
Blackwolf said:
My bike is all original and has never been messed with. I bet the ignition cover hasn't been opened since Guido first put the screws in. It looks like it has been in a time capsule for 47 years. It just decided it was time to stop producing voltage on one side. I would like to hope it's a reliable as you say. Once I get the condensers in I will see.
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Fingers crossed then. Apparently, condensers age badly.

I haven't followed the whole thread. Have you checked with a simple multimeter or even just a 12 V bulb, if you're getting juice from the coils right down to the points? Are your coils fed?

Paul
 
Blackwolf said:
How do you go about re-locating the condensers? Do you just attach the wire to the coil? That seems way to easy. There must be more to it than that. I am all for simplicity and reliability.
Click to expand...
re-locate for sure (anywhere) .... connections can be short or a metre or so
 
Paul Marx said:
Fingers crossed then. Apparently, condensers age badly.

I haven't followed the whole thread. Have you checked with a simple multimeter or even just a 12 V bulb, if you're getting juice from the coils right down to the points? Are your coils fed?

Paul
Click to expand...
Well Paul, To give you a quick summary of my issue with the ignition, I have an engine that starts, runs but the right exhaust is stone cold....No spark. Replaced the coil, plug wire and spark plug and still no spark and a cold pipe. I am assuming it's a condenser because I had one fail on a car of mine back in the 70's and the condenser failed when the car drove thru a dip in the road and the shock killed the condenser. The bike ran fine when I bought it and while driving home with it in the back of my truck, it must have jarred it enough to kill the condenser (I assume). So here I am and I have to put the new ones in but I need to grind off the rivets that secure them but that's an issue for tomorrow when I can take it to work where I have the facilities to do the job properly.
I am totally open to remote mounting the condensers but I have no idea on where to locate them or for that matter, how to even wire them up. I know they only have one wire but where do I connect the wire? Should I mount the condensers to an aluminum plate and go from there. I want them located in such a place I can replace them in a minute or so, assuming they are the Achilles heal to this engine. Does it matter how long the wires are and how far they are from the points? You may know by now I have no clue on the workings of an ignition system except that when it works, all is good.
 
Not sure why you want to further complicate or add another element to your issues if you are unsure of process.
Why not just, for now, replace the condensors by simply drilling out rivets and bolting on new ones as said on previous page by a couple of us. It is very simple!
You can then set it up correctly and start chasing any spark, fuel or timing issues you may or may not have.
Once you have everything working correctly you can change what you want ensuring each change is done correctly............
(your new condensors should be good for quite a few rides around the block.....)
 
Blackwolf said:
Well Paul, To give you a quick summary of my issue with the ignition, I have an engine that starts, runs but the right exhaust is stone cold....No spark. Replaced the coil, plug wire and spark plug and still no spark and a cold pipe. I am assuming it's a condenser because I had one fail on a car of mine back in the 70's and the condenser failed when the car drove thru a dip in the road and the shock killed the condenser. The bike ran fine when I bought it and while driving home with it in the back of my truck, it must have jarred it enough to kill the condenser (I assume). So here I am and I have to put the new ones in but I need to grind off the rivets that secure them but that's an issue for tomorrow when I can take it to work where I have the facilities to do the job properly.
I am totally open to remote mounting the condensers but I have no idea on where to locate them or for that matter, how to even wire them up. I know they only have one wire but where do I connect the wire? Should I mount the condensers to an aluminum plate and go from there. I want them located in such a place I can replace them in a minute or so, assuming they are the Achilles heal to this engine. Does it matter how long the wires are and how far they are from the points? You may know by now I have no clue on the workings of an ignition system except that when it works, all is good.
Click to expand...
not sure if condensors are essential (?) ... don't they just save the points from arcing? (should still run?)

p.s. I may be totally wrong!
 
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