Cold weather cough / sputter / backfire - Honda Shadow Forums : Shadow Motorcycle Forum

metrocane · 10-30-2011, 01:54 PM

I have a 2003 shadow ace vt750. it stumbles, coughs and backfires through carburator at all times when the ambient tempurature is below 65 degrees. Not cold engine, but cold weather. In hot weather its fine. The problem is at light throttle. It accelerates fine. Its when you back out of the throttle to cruse
just to be clear. the engine is at operating temp.
its associated with cold intake air
Any input ?
Thanks

93gc40 · 10-30-2011, 02:13 PM

What mods to the intake and exhaust and carbs???? how much choke do you normally use at start-up, warm day???? Could just need to adjust the AF mixture a tad.

Scrapdog2grand · 10-30-2011, 02:43 PM

as ^93 stated what r yours mods if any. B/F through the carb is usually air fuel mixture related. thats why it only presents it self with colder temps, the mixture leans out with the denser air.

Big B · 10-30-2011, 03:06 PM

Agree w/ the above comments. Try fattening it up a bit and maybe run some seafoam through the fuel system

metrocane · 10-31-2011, 11:07 AM

I have the A/F set at 3 1/2 turns
It is stock with no mods to the intake or exhaust
Generaly no choke is needed, but I always pull it to get fast idle
It only has 3400 miles on it " 2003 vt750" the last 1500 miles with seafoam or b12
It had valve adjustment, plugs, carbs cleaned and sinked and general service 1500 miles ago
I thought about oiling the air filter for the winter. What are your thoughts on that ?
Thank you

metrocane · 10-31-2011, 11:12 AM

One more thing. Here in Atlanta we have oxygenated fuel. about 10 %. Seafoam has alcohol and ads to the problem. But not a lot I can do about that

93gc40 · 10-31-2011, 11:22 AM

Are the symptoms affected by the amount of choke, used? IMO, if you don't NEED at least some choke cold start-up, below 70 ambient, your too RICH. Mine is very cold blooded, needs 1/4 choke for 2 minutes at 80 degrees, to acheive normal idle. You might try adjusting the chokes and the floats. If your filter is designed to be oiled, then oil it, if NOT designed for oil DON'T oil it. What is RPM your bike idling at warmed-up, after 15 minutes of riding??????

93gc40 · 10-31-2011, 11:29 AM

Quote:

Originally Posted by metrocane

One more thing. Here in Atlanta we have oxygenated fuel. about 10 %. Seafoam has alcohol and ads to the problem. But not a lot I can do about that

If yor are using a fuel additive in more than 1 or 2 tanks in 10, you are going to do more damage than good. Your fuel and seafoam should cause a lean condition. Your problem sounds like rich condition or ignition issue, IE cough and BF through carb.

metrocane · 10-31-2011, 12:10 PM

I just tried it
60 deg. and it did need 1/2 choke or more to start
It idles at 1000 rpm after warm up
Thanks

10-30-2011, 01:54 PM	#1 (permalink)
metrocane Member Join Date: Feb 2011 Location: Atlanta Posts: 30	Cold weather cough / sputter / backfire I have a 2003 shadow ace vt750. it stumbles, coughs and backfires through carburator at all times when the ambient tempurature is below 65 degrees. Not cold engine, but cold weather. In hot weather its fine. The problem is at light throttle. It accelerates fine. Its when you back out of the throttle to cruse just to be clear. the engine is at operating temp. its associated with cold intake air Any input ? Thanks

10-30-2011, 02:13 PM	#2 (permalink)
93gc40 Senior Member Join Date: Nov 2008 Location: Visalia, CA Posts: 4,462	What mods to the intake and exhaust and carbs???? how much choke do you normally use at start-up, warm day???? Could just need to adjust the AF mixture a tad. __________________ 93 VT1100C Harley Killer (1150cc), VH Exhaust, 2mm sleeved and bored, Modified Heads and Valves, Adjustable Timing, Touring Seat, Baby Apes, Metzlers

10-30-2011, 02:43 PM	#3 (permalink)
Scrapdog2grand Senior Member Join Date: Sep 2011 Location: New Jersey Posts: 1,502	as ^93 stated what r yours mods if any. B/F through the carb is usually air fuel mixture related. thats why it only presents it self with colder temps, the mixture leans out with the denser air. __________________ 1999 VLX 1998 SA750 2003 SA750 http://www.cycleterminal.com Motorcycle Terminals, Connectors,Relay Kits, Accessories, Wiring diagrams. Site still under construction.

10-31-2011, 11:22 AM	#7 (permalink)
93gc40 Senior Member Join Date: Nov 2008 Location: Visalia, CA Posts: 4,462	Are the symptoms affected by the amount of choke, used? IMO, if you don't NEED at least some choke cold start-up, below 70 ambient, your too RICH. Mine is very cold blooded, needs 1/4 choke for 2 minutes at 80 degrees, to acheive normal idle. You might try adjusting the chokes and the floats. If your filter is designed to be oiled, then oil it, if NOT designed for oil DON'T oil it. What is RPM your bike idling at warmed-up, after 15 minutes of riding?????? __________________ 93 VT1100C Harley Killer (1150cc), VH Exhaust, 2mm sleeved and bored, Modified Heads and Valves, Adjustable Timing, Touring Seat, Baby Apes, Metzlers

10-31-2011, 11:07 AM	#5 (permalink)
metrocane Member Join Date: Feb 2011 Location: Atlanta Posts: 30	I have the A/F set at 3 1/2 turns It is stock with no mods to the intake or exhaust Generaly no choke is needed, but I always pull it to get fast idle It only has 3400 miles on it " 2003 vt750" the last 1500 miles with seafoam or b12 It had valve adjustment, plugs, carbs cleaned and sinked and general service 1500 miles ago I thought about oiling the air filter for the winter. What are your thoughts on that ? Thank you

10-31-2011, 11:12 AM	#6 (permalink)
metrocane Member Join Date: Feb 2011 Location: Atlanta Posts: 30	One more thing. Here in Atlanta we have oxygenated fuel. about 10 %. Seafoam has alcohol and ads to the problem. But not a lot I can do about that

10-31-2011, 12:10 PM	#9 (permalink)
metrocane Member Join Date: Feb 2011 Location: Atlanta Posts: 30	I just tried it 60 deg. and it did need 1/2 choke or more to start It idles at 1000 rpm after warm up Thanks

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