Spark

45u

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Feb 18, 2016
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Georgia USA
I only get a very thin spark not as blue as I would like and it will not start. It has not even popped. I have even replaced the CDI and stator not any better? I have even put gas down the plug hole and still not even a pop. I have tried holding it wide open in case it is flooded. Sure does not seem to be a really good spark like on everything else I have ever worked on! I checked the air gap between the rotor and stator to make sure it is not hitting on one side and I tried two NEW NGK plugs. Any suggestions?
Thanks
Jeff
 
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spark is always a bit thin at cranking speed - check that gaskets and seals are good and no air leaks at carb - if this is a new motor, it has to be something simple
 
I took the whole motor apart before I even turned it over because of all the shavings and trash inside and I see why they want you to run it so oil rich when new to flush out the trash. I torqued the cylinder nuts to recommended specifications. Do to the tight fit I started out with a SHA clone carb. There is gas in the exhaust pipe and in the cylinder and has compression. It has never popped so I would think it has to be fire. I even replaced the WHOLE ignition system. I have 4 NEW plugs with the gap set at .025 and the ignition will only make one of them spark. I have the rear wheel off the ground so I can turn the motor over and check spark. I get it going at least as fast as I would riding it and popping the clutch. Last night I ordered ANOTHER ignition system and if this does nothing I will order a new rotor.
Thanks
Jeff
 
not sure what 'whole motor apart' means, but there are a LOT of mistakes that can happen with rotor timing, seals and gaskets if everything was apart

maybe once in 100 motors do I see something in the motor that shouldn't be there, but usually not something serious - if you do get a new motor, leave it together
 
Little back ground on myself. I have been riding and working on including but not limited to machine work on motorcycles for over 40 years much of the time as s living. If you give me a shout out crank and a rod kit I can build that as well. When I said take apart do to all the grit and dirt in the motor I went as far as split the cases installed all new gaskets and torqued to recommended specifications from here. I even had to flush and lube the rod bearing as it was stiff till I did this showing it all so had dirt in it. I SEE WHY THEY WANT A PERSON TO RUN SO RICH WITH OIL WHEN NEW. Just one of my many babies. LOL
Thanks
Jeff
 

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my first guess then is that rotor is on backwards - with key way at 1 o'clock, check that rotor is almost exactly horizontal
 
my first guess then is that rotor is on backwards - with key way at 1 o'clock, check that rotor is almost exactly horizontal
ditto that, but its so obvious really, that surely someone with 40+ years mechanical experience, including making cranks etc, couldnt possibly make such a simple mistake.
 
for someone new to these, the info on timing may be hard to find
 
replace the magnet that powers the stator coil.
also remove the shellac from the stator coils mounting screws. they provide the ground path from the spark plug to the ignition system and anything less than perfect raw metal to metal contact there will provide unwanted resistance to current flow.
 
Recently I purchased a replacement magnet on ebay to troubleshoot a performance problem. The engine is a 2011 build Grubee Skyhawk 66 received in 2012.

magnet comparison.jpg


The magnet on the left is the original marked out to prevent reinstalling it backwards. The magnet on the right was shipped from a vendor on ebay. Just from visual inspection without even taking a measurement is is apparent from the key slot positioning that the timing would be different. I contacted the vendor pointing out that from what I know about the motor his part would advance the timing a great deal and this could damage the motor. Therefore, he should not sell this part as a generic replacement. The vendor responded that the picture of the part on ebay was information enough about the compatibility and was offered to return my payment if I returned it. No shipping reimbusement.

I have heard before the wisdom of buying parts from the manufacturer of the motor but I have been having good luck, if not better luck, buying parts on ebay. The magnet is a married setting to the crankshaft and if any part has to be bought from the original manufacturer it's the magnet. Since the positioning of the key slot is so critical it raises the question of is this even good enough. The case is made for having a adjustable CDI ignition.
 
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