750 sf ignition problem

Perry said:
Still don't know if he's got a spark on the cold side. For some reason I feel I really need to know. Anyone live near by ?
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Still no spark on the left side, but I found a guy somewhat local who's going to look at it. I just have to truck it out to him and probably wait a few weeks. Not a problem as long as it runs. I will keep everyone posted as to what the mystery is.
 
Blackwolf said:
I did have fuel leakage thru the carburetors at one time. I pulled them off and cleaned them out. Bought new floats, needle and seats along with gaskets and fuel lines. I also put in a pair of inline filters. That problem is solved and fuel flow is as it should be.
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Great that it's fixed, but that's only until it isn't again, it's an expensive lesson to learn.
 
On the last leg of the way home this summer, my SF2 decided not to wake up in the morning after I'd packed the bike and dressed up as a motorcyclist.
When I'd pushed it into the court yard of our lodgings the previous evening, the idiot lights flickered on when I pushed the bars to one side manoeuvring the bike. It had happened once before on our trip. I was suspicious of chaffed wiring around the steering head. I thought that a short had emptied the battery overnight.
I whipped out my 12 V bulb and tested the battery. Fiat lux!
So I went around the wiring, pulling and wiggling. I was very close to giving up after about an hour when wiggling under the instrument console flashed the idiot lights on. It turned out that one wire was parting company with the ignition switch.
Rip the wires off, brown and red together and we have lift off for the 300 km ride home, looking like thieves at every stop when stopping involved separating the two wires and starting, joining them again.

PaulWires.jpg
 
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Coming home from Tassie I had a little woopy doing a U-turn and fell over, after that the bike started cutting out and restarting without warning. It gradually got worse, it was looked at that night but nothing was found as it was intermittent. I was pissed off to the max as I was slowing progress and after 12 days away the 10 or so riders just wanted to get home. So the decision was made to stop off in Bungandor at Steve Bs place and while there a complete temporary ignition wiring loop was added, no key or kill switch to avoid THE ISSUE. It got me home the last 300ks and next weekend Brett front the broken earth wire 75mm away from the battery earth point, the battery strap had broken during that Woopy allowing the battery to move and break that wire internally, it nearly connected inside its insulation. That killed all 3 sparks intermittently so obviously not this bikes issue. But it will be similar. BTW I just had a thought, I once lost spark to the 2 outer plugs and fixed that tightening the double-ended coil mount to the frame, give it a go. It's a 30 second bolt nip that again got me home the last 300ks from an early Snowy Run. The coils are up under the fuel tank, an easy job to try.
 
martymoose said:
Yes you are... Won't run at all without condenser
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will it run (?) most likely not (and not going to try it) but for trouble shooting / diagnostic (which is the thread) anything from a bypass wire or globe or even grab the spark plug (tongue in cheek) can help. I bench tested a coil / plug and battery yesterday .... and yes, you can trigger a spark-plug (whenever you break the connection to the coil)

The condensor has a few jobs .. acts as a damper for the coil and reduces the arcing over the points (which is quite severe)

and I'm not an electrical engineer - so explanations are 'basic' but I hope it helps our understanding of the ignition systems
 
You can actually make a spark without a condenser but it's very weak. I've done it for test purposes but could barely see or hear the spark. It was only just there. Connecting a condenser brought the healthy spark back.

Preventing arcing at the points isn't just to stop the points eroding. It's vital to the function of the ignition.

An intuitive explanation is that the coil needs a rapid collapse of the magnetic field to induce a high secondary voltage and make a good spark. The quicker that happens the better. If the points are allowed to arc, the primary current will continue to flow through the arc for a time, which sustains the magnetic field for a while, slowing it's collapse rate. We're only talking micro-seconds, but that's a long time as far as the coil is concerned.

Arcing is generally not a good thing in electrical switching. Electrical substations go to a lot of trouble to prevent it.
 
Dellortoman said:
You can actually make a spark without a condenser but it's very weak. I've done it for test purposes but could barely see or hear the spark. It was only just there. Connecting a condenser brought the healthy spark back.

Preventing arcing at the points isn't just to stop the points eroding. It's vital to the function of the ignition.

An intuitive explanation is that the coil needs a rapid collapse of the magnetic field to induce a high secondary voltage and make a good spark. The quicker that happens the better. If the points are allowed to arc, the primary current will continue to flow through the arc for a time, which sustains the magnetic field for a while, slowing it's collapse rate. We're only talking micro-seconds, but that's a long time as far as the coil is concerned.

Arcing is generally not a good thing in electrical switching. Electrical substations go to a lot of trouble to prevent it.
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exactly ... a diagnostic tool
 
I’m hanging out to hear what the problem is/was. Hopefully something silly, nothing worse than getting something home that doesn’t work, but did when you bought it ........ :unsure: and now I wonder where that sensible and empathetic statement came from. Maybe I need a testosterone boost?
 
chrisk said:
I’m hanging out to hear what the problem is/was. Hopefully something silly, nothing worse than getting something home that doesn’t work, but did when you bought it ........ :unsure: and now I wonder where that sensible and empathetic statement came from. Maybe I need a testosterone boost?
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Its your time in the naughty corner CK, its given you time to contemplate on your
interactions with others.....

Yeah .... nah..
Probably just alcohol induced.
 
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