   Posts: 8 Gender:
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Post subject: Re: Spark plug reading Posted: Mon May 10, 2010 1:58 pm |
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varroa wrote: that way does not work with scooters. even if you shut off the engine, the automatic transmission still keeps the clutch engaged. so yes, there is fuel pumping through the engine, although the plug is not firing. Explain how there is "pumping" which would mean there is pressure, there should be no pressure. I am new to this ruckus thing, but if there is no fuel pump there is no pressure. If you kill the motor, fuel will continue to go into the carb, until you shut the fuel off, and even then the fuel sits in the float bowl.
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varroa
Donkey Puncher


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      Posts: 5047 Location: Manhattan, NYC Gender:
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Post subject: Re: Spark plug reading Posted: Mon May 17, 2010 10:57 pm |
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like i mentioned before, the automatic transmission in the ruckus connects the engine to the rear wheel at RPMs above 3500, or - if you are slowing down from an engine-accelerated run - at speeds above ~3-5 mph. there is no way to break that connection unless you slow down enough for RPMs to drop below 4000. which takes a few seconds from 40 mph. during those seconds, the engine will make
since, when talking about WOT runs, we mean 30-40 mph driving, it is natural that the engine stays engaged with the rear wheel even if you cut the ignition completely, until you slow down to about 4000 RPMs. that means that the engine will revolve a few hundred times since the moment you flip the kill switch. during those revolutions, there will be gasoline pumping through the combustion chamber, cleaning out the spark plug - not sure by how much, but it definitely does.
peope did come up with an idea to have a manual clutch instead of the stock automatic one, but it never has been realized.
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Blackruk wrote: Sooo . . . who wants to sue somebody? 
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oldfart55
Shot Caller


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   Posts: 1440 Location: springfield, MO Gender:
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Post subject: Re: Spark plug reading Posted: Sun Aug 01, 2010 11:12 am |
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Okay, I'm no expert, so this falls under the FOR WHAT IT'S WORTH category. I've been playing with jets since I opened my intake, and I think I've got it about dialed in. With a 38 slow jet, an 88 main turned my plug base ring almost black, and I had a very slight stumble at WOT. An 85 runs great through the whole throttle range, but after 2 hours hard riding, my plug looked brand new, no coloration at all except for a slight white deposit in the outside of the ground strap. I thought this might indicate a lean condition ( I need an 86.5 jet  ). I've read everything I can find about reading plugs, so I sent an email to tech support at NGK, with a detailed description of the plug with the 85 jet. Great people, I got an answer the same afternoon. He said pretty much the same thing as Smartbomb, that unleaded pump gas colors a plug very little, and from a tuning standpoint, the main thing to look at is the insulator nose, it should stay clean and white(ish). He said buildup of deposits on the ground strap is normal, and that my plug looked like it should. Black or dark brown is definitely too rich. Good enough for me. 
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