GY-5 backfiring, popping- more information, see 2nd pg. - Page 3

Kawazacky · 05-13-2008, 08:07 PM

It's the original plug. I'm going to buy a replacement, and some carb cleaner tomorrow.

warrior91 · 05-13-2008, 08:09 PM

I bet you a can of carb cleaner your backfire clears up with the plug replaced!

AZ200cc · 05-13-2008, 08:12 PM

Quote:

Originally Posted by warrior91

I bet you a can of carb cleaner your backfire clears up with the plug replaced!

None of the generic carb cleaner either

TeamCheap · 05-13-2008, 09:30 PM

Sounds like its sucking air in at the header pipe near the cylinder and the unburnt fuel is causing the popping when it ignites on the hot exhaust pipe.
But I think this has already been covered.

Did you put a new copper gasket in between the header pipe and the cylinder?(just tightening it might not cut it)

ok OK I'm going to my corner and sitting now. :?

Kawazacky · 05-13-2008, 09:45 PM

I didn't put a new gasket in. I just tightened the bolts. And, like I said, I'd think that if this was the problem, it would be less intermittent. The problem only pops up when downshifts take the revs to about 6,000, 6500, OR when the throttle is held steady at around 5000 rpms.

But I'm looking at any possiblities.

VinceDrake · 05-13-2008, 11:10 PM

Mr: Kawazaki:

Does your bike have the "Emission controls" on/hooked up?

If the Air Injection system into the exhaust is leaking, or is missing it's control hose, it *will* pop a gooder when you drop the throttle. Long story short, under low vac (Loaded) conditions, the air injector, or gulper valve should be open, and allowing air into the exhaust stream, reacting with the hot exhaust, and making things all shiny and tree-friendly. The valve should close under hig vac (Decel, idle, etc.) blocking off the gulper. If it doesn't, Bang!

At least on older cars, and some Crapply BMW bikes that had the system, the gulper valve was notoriously craptacular. And it could die suddenly, without any warning, or adjustment on your part.

Solution: Amputate and plug stupid emission control zeug.

Of course, if your bike doesn't have that stuff, I just wasted ten minutes of your life. Sorry about that. (But my post count went up by 1!

)

--Vince

Dragon · 05-14-2008, 11:45 AM

I don't want to hi-jack the post, but I think the following question is relevent. Is low level of popping during deceleration considered normal?

red2003 · 05-14-2008, 12:21 PM

Quote:

Originally Posted by Ream

Try to screw the air screw IN ( your idle circuit is too rich) a little & go ride.If it`s better,screw IN a little more, just til it stops popping @ decel.

Our bikes don't have an air screw, they have a fuel screw, so in = leaner, out = richer. My bet is you have a bad CDI, or a wire grounding out. Check as Alonzo stated earlier.

IronFist · 05-14-2008, 12:48 PM

Vince:
"notoriously craptacular"

Thanks man, I needed that/

Kawazacky · 05-14-2008, 02:56 PM

A can of carb cleaner, and a new spark plug have not solved the problem.

I will try swapping in my friend's CDI from his GY-5, and if that doesn't work....I suspect I'll pull the carb next, to look inside.

red2003 · 05-14-2008, 03:02 PM

Quote:

Originally Posted by Kawazacky

A can of carb cleaner, and a new spark plug have not solved the problem.

I will try swapping in my friend's CDI from his GY-5, and if that doesn't work....I suspect I'll pull the carb next, to look inside.

Don't forget to look for a grounded wire!

Kawazacky · 05-14-2008, 03:37 PM

I already gave it a quick once-over, but didn't see anything. I spent three hours on the exhaust/carburetion system today, and got nowhere. I hope this isn't going to chew up all my free time for the next few weeks.

The bike will pop at 3000 rpms with the throttle slowly opened, then 4000, then 5000 rpms. This opening the throttle, not closing it, which is when leaning problems usually come in.

Rizn · 05-15-2008, 05:31 PM

Does your bike have a rubber boot between the carb and engine, my 4 wheeler was doing the same thing, couldnt figure it out till i found a very small hairline crack in rubber boot mount (whatever it is) replaced with new and its back to normal, well after i set the air/fuel screw and idle screw back to normal

Kawazacky · 05-15-2008, 05:48 PM

Well I am going to try swapping out a different CDI and if that doesn't work, then I'm going to pull the carb and look at it.

05-13-2008, 08:09 PM	#32
warrior91 Join Date: Nov 2007 Location: N.E. Saskatchewan, Canada Posts: 679	I bet you a can of carb cleaner your backfire clears up with the plug replaced! __________________ '91 Yamaha Warrior- stage 2 '83 Honda ATC 70 '08 Yongjiang 125cc mx (Loncin) '08 Yongjiang 150cc atv (Jinlong)
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05-13-2008, 11:10 PM	#36
VinceDrake Join Date: Nov 2007 Location: Southern Saskatchewan Posts: 491	Mr: Kawazaki: Does your bike have the "Emission controls" on/hooked up? If the Air Injection system into the exhaust is leaking, or is missing it's control hose, it will pop a gooder when you drop the throttle. Long story short, under low vac (Loaded) conditions, the air injector, or gulper valve should be open, and allowing air into the exhaust stream, reacting with the hot exhaust, and making things all shiny and tree-friendly. The valve should close under hig vac (Decel, idle, etc.) blocking off the gulper. If it doesn't, Bang! At least on older cars, and some Crapply BMW bikes that had the system, the gulper valve was notoriously craptacular. And it could die suddenly, without any warning, or adjustment on your part. Solution: Amputate and plug stupid emission control zeug. Of course, if your bike doesn't have that stuff, I just wasted ten minutes of your life. Sorry about that. (But my post count went up by 1!) --Vince __________________ "Sometimes it is better to say nothing, and let people think you're an idiot, than to open your mouth and prove it."
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05-13-2008, 08:07 PM	#31
Kawazacky Join Date: Mar 2008 Location: Saint John, N.B. Posts: 279	It's the original plug. I'm going to buy a replacement, and some carb cleaner tomorrow.
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05-13-2008, 09:30 PM	#34
TeamCheap Join Date: Jun 2006 Location: directly under the earths sun............NOW Posts: 2,302	Sounds like its sucking air in at the header pipe near the cylinder and the unburnt fuel is causing the popping when it ignites on the hot exhaust pipe. But I think this has already been covered. Did you put a new copper gasket in between the header pipe and the cylinder?(just tightening it might not cut it) ok OK I'm going to my corner and sitting now. :?
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05-13-2008, 09:45 PM	#35
Kawazacky Join Date: Mar 2008 Location: Saint John, N.B. Posts: 279	I didn't put a new gasket in. I just tightened the bolts. And, like I said, I'd think that if this was the problem, it would be less intermittent. The problem only pops up when downshifts take the revs to about 6,000, 6500, OR when the throttle is held steady at around 5000 rpms. But I'm looking at any possiblities.
	0

05-14-2008, 11:45 AM	#37
Dragon Join Date: Nov 2007 Location: Tejas Posts: 834	I don't want to hi-jack the post, but I think the following question is relevent. Is low level of popping during deceleration considered normal?
	0

05-14-2008, 12:48 PM	#39
IronFist Join Date: Apr 2007 Location: Toronto Ontario Canada Posts: 2,585	Vince: "notoriously craptacular" Thanks man, I needed that/
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05-14-2008, 02:56 PM	#40
Kawazacky Join Date: Mar 2008 Location: Saint John, N.B. Posts: 279	A can of carb cleaner, and a new spark plug have not solved the problem. I will try swapping in my friend's CDI from his GY-5, and if that doesn't work....I suspect I'll pull the carb next, to look inside.
	0

05-14-2008, 03:37 PM	#42
Kawazacky Join Date: Mar 2008 Location: Saint John, N.B. Posts: 279	I already gave it a quick once-over, but didn't see anything. I spent three hours on the exhaust/carburetion system today, and got nowhere. I hope this isn't going to chew up all my free time for the next few weeks. The bike will pop at 3000 rpms with the throttle slowly opened, then 4000, then 5000 rpms. This opening the throttle, not closing it, which is when leaning problems usually come in.
	0

05-15-2008, 05:31 PM	#43
Rizn Join Date: Apr 2008 Posts: 127	Does your bike have a rubber boot between the carb and engine, my 4 wheeler was doing the same thing, couldnt figure it out till i found a very small hairline crack in rubber boot mount (whatever it is) replaced with new and its back to normal, well after i set the air/fuel screw and idle screw back to normal
	0

05-15-2008, 05:48 PM	#44
Kawazacky Join Date: Mar 2008 Location: Saint John, N.B. Posts: 279	Well I am going to try swapping out a different CDI and if that doesn't work, then I'm going to pull the carb and look at it.
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