crank case detonation
02-03-2010, 09:44 PM
#1
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crank case detonation
I think I may be having some crank case detonations from fuel getting past the rings into the crank case and then igniting. It only happens once the engine is warm (gas volatilizes?) and at idle. when it happens there is smoke in the heads carbs and crank case. I don't know what else could go bang and cause all this. Has anyone had this happen? at least one float didn't seem to be closing the other day as there was literally an inch of gas in the intake but I pulled the carbs and couldn't find anything wrong with either float valve. Any Ideas? any one else had something similar happen?
02-03-2010, 09:58 PM
#2
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sounds like another petcock diapraghm fail. I would start by checking that. Then if you think gas got in the crank case you need to change the oil too. Fix the problem then fix the result then go back to riding yee hah. Oh and let us know what you find. I at least like to know mystery solved.
02-03-2010, 10:26 PM
#4
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No, not unless the bike is running in my experience. I had a diaphram fail and didn't know it until I fired the bike, but when I did, gas came pouring out right onto the rear header.
02-04-2010, 07:12 AM
#7
2nd mouse gets the cheese
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well if it gets fuel pooling up in a cylinder when the bike is not running it can only be a couple of things. The petcock (lots of problems with that lately) or the float needles not sealing anymore, which happens it is just that I rarely see that anyone has those fail. I am at 56k miles and my float valves and needles are still original to the bike. It could also be a small piece of crud keeping the float needles open, I have experienced that on another bike. So if you check both of those you have a really good probability of success.
02-04-2010, 09:12 AM
#8
Squid Poacher
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It sounds to me like you may have a crack in your di-lithium crystal that is allowing quantum flux vortexes to swirl out of control into the crankcase where they implode when they impact the antimatter lubricant pump. You should talk to my buddy Geordi, he can fix that right up for ya.
02-04-2010, 10:28 AM
#10
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It sounds to me like you may have a crack in your di-lithium crystal that is allowing quantum flux vortexes to swirl out of control into the crankcase where they implode when they impact the antimatter lubricant pump. You should talk to my buddy Geordi, he can fix that right up for ya.
02-04-2010, 11:26 AM
#11
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You know that is kinda what it sounded like, I just hope all that smoke wasn't the magic smoke, I cannever seem to find my extra or figure out how to get it back in once it's drained
02-04-2010, 12:06 PM
#12
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This may sound really hairbrained but check your alternator.
I've seen a couple of bikes where a shorted alternator ignited the oil fog inside the crankcase and actually blew out the halfmoons at the valve cover gasket.
Really messy when that happens.
No matter what's in your crankcase, fuel or oil, it will only ignite of there is a spark.
The only source for a spark in the crankcase is your alternator.
Kai Ju
I've seen a couple of bikes where a shorted alternator ignited the oil fog inside the crankcase and actually blew out the halfmoons at the valve cover gasket.
Really messy when that happens.
No matter what's in your crankcase, fuel or oil, it will only ignite of there is a spark.
The only source for a spark in the crankcase is your alternator.
Kai Ju
02-04-2010, 06:11 PM
#15
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It still shouldn't take more than a second though.
When you pull the oil filler cap off and sniff it, do you smell fuel or just oil ?
Has the oil level gone up instead of down since the last oil change ?
Both would be signs of fuel getting past the rings and into the engine oil.
With the ignition key in your pocket disconnect the stator plug and check all three yellows to ground which should be infinite or O/L.
Also check yellow to yellow which should be in the low single digits.
A normal charging system will put out anywhere from 60 to 80 plus Volts AC with the Reg/Rec disconnected, more than enough to create a spark if there is a break in the insulation on any of the stator coil wires.
Kai Ju
02-05-2010, 04:34 PM
#16
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I got 3 ohms between wires and infinite resistance to ground. I did notice the petcock dribbled when i shook the tank vigorously. I drained the oil and there sure seemed to be gas in it.
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