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Post by alleyoop on Jul 7, 2013 23:44:23 GMT -5
Big Difference between Popping and Backfire. A POP is just that POP sound, a Backfire is like POW, Which is it? And NONE OR NORMAL so something is wrong. Popping on Decel is also a Lean condition but that happens because the throttle is suddenly closed and it is closed to much and not enough fuel is being fed and it runs lean. It could be caused by to low of an IDLE and or running a little lean on the Fuel Ratio which you can just richen it up a little.
Backfiring on Decel is caused by bad air leak usually by the Header Pipe Flange, a nut came off or loose and most of the time blows out the exhaust gasket to one side. Backfires are not good it can damage your exhaust valve that is a lot of backpressure on the valve and it will burn it.
Alleyoop
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Post by domindart on Jul 7, 2013 23:53:19 GMT -5
Alley,
It is more of a pop, sounds like I ran over a twig.
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Post by alleyoop on Jul 8, 2013 0:03:44 GMT -5
Great, now after it is nice and hot check your IDLE and see if it is a little low the 150s like to idle anywhere from 1500-1800 rpms. If the idle is below that raise the idle a little that will allow more fuel when it comes down to idle after the throttle is closed all of a sudden and will leave the butterfly a little more open and uncover some more of the Pilot Jet fuel outlets for more fuel to get sucked in. If the idle is not low then just richen up the fuel ratio a little usually takes 1/4 -1/2.
Alleyoop
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Post by domindart on Jul 8, 2013 0:06:03 GMT -5
okay, I'll have to locate the screw and turn up the idle
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Post by prodigit on Jul 8, 2013 0:07:41 GMT -5
Big Difference between Popping and Backfire. A POP is just that POP sound, a Backfire is like POW, Which is it? And NONE OR NORMAL so something is wrong. Popping on Decel is also a Lean condition but that happens because the throttle is suddenly closed and not enough fuel is being fed and it runs lean. It could be caused by to low of an IDLE and or running a little lean on the Fuel Ratio which you can just richen it up a little. Backfiring on Decel is caused by bad air leak usually by the Header Pipe Flange, a nut came off or loose and most of the time blows out the exhaust gasket to one side. Backfires are not good it can damage your exhaust valve that is a lot of backpressure on the valve and it will burn it. Alleyoop Sometimes it's inevitable. I've set the idle and AF screw correctly on my bike, but it always pops, unless if I tune it rich. At optimal values (where A/F ratio works best), it pops. If I run it lean, it pops more. If I run it rich (below the the optimal AF setting) it won't pop, but I have less power out of the engine, and less top speed. |
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Post by prodigit on Jul 8, 2013 0:10:48 GMT -5
I personally set my idle ~1000-1200 RPM. Reason being if I'm running WOT for a while, that idle goes up to 1400-1500RPM, and could engage the clutch if regular idle is too high.
Especially if your regular idle is ~1500+ RPM chances are on a hot ride, that your clutch wants to grip in front of a red light,
for that I suggest to lower idle a bit; depending on the outside temperature, 1200-1400RPM should be good enough.
It's better to run the bike with popping sounds, than ride it with a dragging clutch.
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Post by alleyoop on Jul 8, 2013 0:20:10 GMT -5
Any motor will produce more power running a little LEAN but your asking for trouble sooner rather than later. If you like to always be doing rebuilds then by all means run LEAN AND MEAN.
You should always run a little on the rich side at WOT reason is any little thing will make them run LEAN and your won't know it until something goes south. How many on here run the heck out of their motors bent over like a crotch rocket then wipe out their motors. Also if you have to run at WOT all the time to keep your top speed you do not have your scoot setup right.
You should setup the scoot to the speeds your going to be riding at most of the time but NOT AT WOT, you should have some left just for those special occasions that you may need a little more.
Alleyoop
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Post by alleyoop on Jul 8, 2013 0:42:45 GMT -5
If the scoot engages the clutch at very low rpms you have another problem. A clutch should not engage and grab the bell below 2000rpms.
Alleyoop
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Post by scootnwinn on Jul 8, 2013 1:34:57 GMT -5
Alley you are talking to Prodigit his bike is optimized and there us no sense in telling him otherwise. I have finally chased all the pop out of mine. For now I'm sure it will change this fall. Anyway I stand corrected on my normal remark. I vote for exhaust leak btw
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Post by prodigit on Jul 8, 2013 4:08:55 GMT -5
Even when not running at WOT, the choke allows me to adjust the fuel mixture from rich to lean.
Aleyoop, are you saying that where the bike performs optimally, it is actually a bit running LEAN, not perfect A/F ratio?
I thought where the engine performs the best is the perfect A/F ratio. Lean or rich running would decrease performance from that ratio?
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Post by scootnwinn on Jul 8, 2013 6:54:07 GMT -5
We have mentioned before that your bike is running dangerously lean digit. Your bike will make the best HP right before it blows itself up. I think you told me I was just being negative.
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Post by alleyoop on Jul 8, 2013 12:32:28 GMT -5
Lets get back to the OP problem and get him fixed up. PRODIGIT, if you want to continue with your questions start up a thread of your own. Alleyoop  |
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Post by gitsum on Jul 8, 2013 17:17:04 GMT -5
prodigit, other than you, we have already agreed and confirmed that popping on deceleration is not normal.
If you want to accept this and try to give a meaningful answer, that would be helpful.
Otherwise please start your own thread about your machine that has completely screwed up tuning, it has absolutely no bearing on the OP's thread.
You won't listen of course, but if your idle is inconsistent and higher when the bike is hot, your pilot circuit is probably too lean or needs something. And using your choke isn't going to fix it properly. The choke is used specifically to add extra fuel to make it easier to start a cold engine. In warm weather it shouldn't even be necessary to use it, just 10 or 15 seconds of running should smooth out the idle.
Sorry about the interruption domindart ;D
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Post by domindart on Jul 8, 2013 22:36:25 GMT -5
no problem
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Post by domindart on Jul 8, 2013 22:37:49 GMT -5
I'll check the header tomrrow
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..BAD TO THE BONE..
