Author Topic: Cold engine backfiring on deceleration  (Read 10538 times)

Rdeangelis

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Cold engine backfiring on deceleration
« on: April 15, 2012, 08:08:09 PM »
Hey all.  What would cause my bike to backfire when decelerating when the engine is cold?

Ok, originally the bike didn't backfire at all.  Winter hit and when it was really cold the engine would backfire just a couple times after startup when decelerating within the first minute of riding, but not after that.  When it got warmer it wouldn't do it.  I figured the cold was making the oils thick and making it happen, didnt worry about it too much.

Now though it's starting to do it even warm.  It never lasts beyond the first couple minutes of being turned on, and they're not huge backfires, just baby farts, but it doesn't seem like a good thing that it happens every time I first start the bike up again till the engine warms up.  Only when taking the throttle off.

So can anyone tell me what the likely cause of that is and what I can do to remedy it?  Also, are these little backfires going to hurt the engine or parts in any way, or is it just annoying to me?

zombie

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Re: Cold engine backfiring on deceleration
« Reply #1 on: April 15, 2012, 11:53:41 PM »
It is unburnt fuel inside the pipe. The auto choke may be on it's way out. When cold the auto choke allows extra fuel in the air mix to give easier starting. If it fails you will be flooding when warm. If yours is taking longer, and longer to return to Norm. I would replace the choke. It wont hurt anything by back firing a little, but if it gets too bad it can blow a hole in the baffles or pipe.
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Vivo

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Re: Cold engine backfiring on deceleration
« Reply #2 on: April 16, 2012, 02:30:33 AM »
My Super 8 125 back fires. A tiny "tick" sound when decelerating. Does not do that when it was new. Is replacement of the choke the only answer? can't this be serviced or anything?
« Last Edit: April 16, 2012, 02:33:29 AM by Vivo »

zombie

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Re: Cold engine backfiring on deceleration
« Reply #3 on: April 16, 2012, 03:04:20 AM »
Some times the idle mix screw is far enough out of wack to make it happen. But if it only happens when cold it is the choke. You can actually buy a whole carb on ebay for parts cheaper than buying an OEM choke. Any gy6 type carb will work for parts
http://www.ebay.com/itm/NEW-50CC-SCOOTER-MOPED-GY6-CARBURETOR-CARB-SUNL-ROKETA-/330476352602?pt=Other_Vehicle_Parts&hash=item4cf1ecf45a&vxp=mtr
"They have nothing in their whole imperial arsenal that can break the spirit of one Irishman who doesn't want to be broken."   Bobby Sands...

Vivo

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Re: Cold engine backfiring on deceleration
« Reply #4 on: April 16, 2012, 03:06:44 AM »
Buy a whole carb assemby? wow! my scoot is only 7 months old!

zombie

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Re: Cold engine backfiring on deceleration
« Reply #5 on: April 16, 2012, 03:10:10 AM »
I'm suggesting buy the carb. just for the auto choke. You'll want the slide/diaphragm too. You can toss the rest in the bin. The choke alone is 40 bucks shipped from any OEM source. The math says... whole carb. = $avings
"They have nothing in their whole imperial arsenal that can break the spirit of one Irishman who doesn't want to be broken."   Bobby Sands...

Vivo

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Re: Cold engine backfiring on deceleration
« Reply #6 on: April 16, 2012, 03:15:23 AM »
Thanks Zombie! :)

zombie

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Re: Cold engine backfiring on deceleration
« Reply #7 on: April 16, 2012, 04:05:09 AM »
 ;)
"They have nothing in their whole imperial arsenal that can break the spirit of one Irishman who doesn't want to be broken."   Bobby Sands...

Rdeangelis

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Re: Cold engine backfiring on deceleration
« Reply #8 on: April 16, 2012, 06:46:32 PM »
Thanks for the info!  I'm planning on checking valve clearances sometime soon too, so that'll be a good chance to look around inside the scoot a little more and get a little familiar.

zombie

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Re: Cold engine backfiring on deceleration
« Reply #9 on: April 17, 2012, 12:31:19 AM »
You can take whole scoot apart with just the tools that fit in your pockets. It is really fun once you've opened it up a few times.
"They have nothing in their whole imperial arsenal that can break the spirit of one Irishman who doesn't want to be broken."   Bobby Sands...

Vivo

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Re: Cold engine backfiring on deceleration
« Reply #10 on: April 17, 2012, 09:14:52 AM »
You can take whole scoot apart with just the tools that fit in your pockets. It is really fun once you've opened it up a few times.

It's not fun in the Super 8. You need to wrestle a lot with the panels before you can take them out. The hardest part is the assembling back. It's just a good thing the plastics are tougher than some scoots.

sentinex

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Re: Cold engine backfiring on deceleration
« Reply #11 on: April 18, 2012, 01:54:16 AM »
Well it seems I have that issue, the super 8 started to backfire a little yesterday and today when cold, and I don't think the carb is going out, the super 8 is 1 and a half Month old. Wonder if it needs some adjustment.
« Last Edit: April 18, 2012, 02:51:41 AM by sentinex »

Vivo

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Re: Cold engine backfiring on deceleration
« Reply #12 on: April 18, 2012, 02:17:34 AM »
Well it seems I have that issue, the super 8 started to backfire a little yesterday and today when cold, and I don't think the carb is going out, the super 8 is 1 and a half old. Wonder if it needs some adjustment.
That makes three of us already on this thread. Three Super 8s. Hmmm...think, think...

I found this in another site.  http://www.ch250.net/techtips/21.htm   Although its for a different scoot, the principle behind may help.
« Last Edit: April 18, 2012, 02:25:31 AM by Vivo »

zombie

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Re: Cold engine backfiring on deceleration
« Reply #13 on: April 18, 2012, 02:30:11 AM »
Yeah I would have said all that but the "Q" button fell off my keyboard.
Excellent score Vivo!!!
"They have nothing in their whole imperial arsenal that can break the spirit of one Irishman who doesn't want to be broken."   Bobby Sands...

Vivo

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Re: Cold engine backfiring on deceleration
« Reply #14 on: April 18, 2012, 02:36:15 AM »
Hahaha!!! Good morning sir!!!

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