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Discussion Starter · #1 ·
Hey there, new to the forum and to the motorcycle world in general. I bought an 07 Bonneville earlier in the year which up until recently had been pretty reliable. First started noticing a lot of back firing on deceleration followed by some hard starting when cold. Eventually wound up with a dead battery that I replaced. Bike worked well for 2 rides then it refused to start one day. Discovered I had no spark at the plugs. I replaced the coil with a nology profire coil and the bike ran like a champ for 2 rides.

today however, the bike would not start. Just checked and once again I have no spark. Any ideas?
 

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As Rich says, pick-up coil or igniter.

The most likely cause of the symptoms you describe would be your pick-up coil (crank position sensor) on its way out -- plenty of threads on this forum on the grief caused by these little beggars... Sometimes working, sometimes not -- it won't start at all; or, if you can get the bike started, it'll run til up to temperature, then it'll just conk out. Generally about as reliable as a chocolate teapot. The pick-up coil can be tested, but replacing it isn't exactly expensive either, and is an easy job for the home mechanic.

Another, less likely possibility (in my opinion), is the igniter/CDI. They can fail, but more likely it'll be the plug to the igniter/CDI -- check for signs of rubbing on the bottom of the seat pan -- and try scientifically wiggling the plug whilst hitting the start button, you might just get lucky!
 
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I agree with Rich and H3CT1C.

First, check the crank position sensor gap. It should be 0.8mm or slightly less. Then you can consider whether you want to test it and/or replace it. To replace, read up on removing the stator cover and putting it back on, get a new gasket for it, and plan to spend some time scraping off the old gasket. Also, the connector for the coil is difficult to access; it sits in a nearly inaccessible spot on top of the airbox.

My approach when I had similar symptoms was to replace the crank position sensor. I didn't want to go to the trouble of removing/reinstalling the stator cover multiple times. This didn't solve my problem--it was the ignitor--so I have an old one that might still be good.

Then there's the ignitor. There's no way to test it, although you can check if the seat pan is pushing on it. Also unplug it and plug it back in once or twice, determine if that does anything. If all else fails, you can replace it with a Procom or TTP ignitor, but that costs about $275. Don't waste money on a new OEM ignitor for twice as much.
 

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Discussion Starter · #5 ·
Thanks for the replies. I managed to unplug the crank position sensor and test its resistance. I measured 609 ohms. I read on this post…Ignition pick-up coil / Crank position sensor (nerdy AND...
the expected resistance to be between 504-616 ohms. So I suppose it’s still within spec?

i removed the stator cover to measure the air gap on the sensor. I measured it to be 1.2mm. So closing that gap to 0.8 should be the next move.

What do you think, should I replace the sensor since I’m “already in there”?
 

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Hmmm... Yes, you are in spec -- but I've had a 'no spark' situation on my bike three times, and on my buddy's Bonneville twice (admittedly the bikes ran with the engine cold, but as they warmed up they'd conk out - so not exactly the same as your situation) -- and each and every time replacing the pick-up coil (which measured in spec every time!) fixed it every time! So yes, if it were my bike, I'd replace the pick-up coil anyway. It's also cheaper to replace than the igniter. If you're not afraid of a little 'user modification' you can replace the Triumph pick-up coil with one made by Electrex in the UK for a part made for a Ducati (I did a 'Frankenspark!' write-up in the 'other parts that fit our bikes' sticky) Mine's two years old and going strong...

Another thought just occurred to me: IIRC a faulty sidestand switch (part of the clutch/neutral safety circuit) can cause a total 'no spark' situation - my bike's been non-standard for so many years I can't remember exactly . If my memory serves me correctly you can bypass and test the sidestand switch: follow the wire up from the switch and disconnect the plug -- on the loom side connector join the two pins with a short section of wire: this tells the safety circuit the side stand is up and it's safe to start the bike. If the sidestand switch is faulty the safety circuit is permanently seeing 'sidestand down' and disables the spark at the igniter -- though the bike will still crank, possibly still in gear . This is one of the reasons I did away with the Triumph safety circuit and came up with my own: by earthing the starter solenoid through the neutral switch the bike can't crank unless the bike's in neutral....

Tim
 

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Test your CPS when hot. You will find a huge difference if itx faulty. Like most things electrical and electronic, breakdown problems show when they get hot. This how I traced a faulty CPS on my car and snowmobile. I tested continuity through it when it was when cold and the engine woild run, there was. Then I ran the engine until it was hot and quit, and immeciately retested the CPS. There was no continuity. Fault found. Different sensors will have differenr specs, the point is the difference between hot and cold readings.
 

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Thanks for the replies. I managed to unplug the crank position sensor and test its resistance. I measured 609 ohms. I read on this post…Ignition pick-up coil / Crank position sensor (nerdy AND...
the expected resistance to be between 504-616 ohms. So I suppose it’s still within spec?

i removed the stator cover to measure the air gap on the sensor. I measured it to be 1.2mm. So closing that gap to 0.8 should be the next move.

What do you think, should I replace the sensor since I’m “already in there”?
Before throwing parts at it a little more troubleshooting should be done. With the ohmmeter connected - heat the sensor with a heat gun and watch results. If reads show failure, reset gap to spec, and repeat.
either way, the gap should be reset to the 0.8mm spec and try it.
 
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Discussion Starter · #9 ·
Just put a heat gun up to the cps while measuring its resistance. It measured 780 ohms at 160*f.
I suppose this reading is normal though my no spark problems never appeared when the bike was hot, only when it sat over night.
 

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Reset the gap to spec. and see if that takes care of your firing problem. When cold the gap would even be slightly wider than the 1.2mm you measured. The old setting Triumph sent some early bikes out was 0.1mm and later after issues were arising they did an update to the .08mm spec.
 

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Set the gap to 0.8mm (not 0.08mm). This might fix it.
 

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That does not sound like the gap would be something that could start being an issue so quick - but I would still set it to the .08mm. Re-reading your original post - I still support the CPS as the only thing I can see that you have not ruled out completely. You have a new coil, a new ignition control module, new plugs & wires. Maybe, big maybe the stator has failed?
 

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Could well be the plug going into the ignitor as mentioned. You heat tested the CPS so I suspect it is OK ( I was going to suggest a dunk in boiling water).
Corrosion on the contacts or gradual loosening of the receiving connectors around the plug pins can cause issues.
I would suggest a good soak with WD40 and then plug it in and unplug it a few times.
After that, you may want to find someone with a working Bonnie of the same year that you can swap your ignitor box into temporarily. That will prove if your ignitor is a problem or not.
 

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Rich, If I recall without re-reading the whole post I think he tried an ignition unit already. Using a heat gun to test is a little easier as it can be done on the bike without removal, that's why I suggested that method.
 

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Discussion Starter · #16 ·
I've replaced the original coil with a Nology Profire but I haven't replaced the igniter. The bike doesn't have any signs of corrosion as I'm in southern California so we don't really have that issue. I'll give disconnecting the igniter connector a try and clean it with some electrical contact cleaner spray. I have a new CPS I received yesterday but I'm going to adjust the air gap to 0.8mm first before replacing it. I should have some time to work on it later tonight or tomorrow AM. I'll be sure to follow here with the results.
 

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Discussion Starter · #17 · (Edited)
Happy thanksgiving!

Adjusted the air gap to 0.8 mm on the original cps; No spark
Installed the new cps and set the air gap to 0.8 mm; No spark
Cleaned the igniter connector with electrical cleaner; No spark

Anyone have a known working igniter that they would be willing to send me for testing?
 

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No experience with a scrambler but looking at a America / Speedmaster wiring the ignition switch supplies 12 volts to the coils, this can be checked with a test light or volt meter. The coil wire coming from the igniter / ignition control unit supplies the ground to complete the primary circuit, off and on to cause the coil to spark. Try using a test light from the ground / igniter side of the coil to the ignition switch side ( hot ) to see if you get a pulse while starting the engine. Test both coils, if one side pulses and the other doesn't you probably have a bad igniter or wiring problem from igniter to coil.
My Haynes manual shows the scrambler wiring same as the Thruxton, which is not correct. Looking at the Speedmaster wiring, also 270* engine, the wire from igniter pin # 8 goes to one coil and wire from pin# 14 to the other. Hopefully someone will verify the scrambler pin numbers.

Good luck, R.
 
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