VT1100 Backfire - Honda Shadow Forums : Shadow Motorcycle Forum

Reply
 
LinkBack Thread Tools
Old 12-08-2009, 08:43 PM   #1 (permalink)
Junior Member
 
cignadude's Avatar
 
Join Date: Nov 2009
Posts: 25
Default VT1100 Backfire

Hi guys, me again. I've been tinkering with the bike and found that the air/fuel mixture screw on the right hand (brake side) of the bike doesn't affect the running of the bike at all. If I screw the one on the left side (clutch side) the bike will die but with it idling I can screw the right side screw all the way in or out and it does nothing. The bike still backfires on deceleration and now it does the same on acceleration. I have sync'd the carbs and tried setting mixture screws at 3.25 turns each (i have aftermarket Vance & Hines exhaust) Even when the right side screw is all the way in it appears the front cylinder still fires after you turn the throttle a little way. it doesn't appear to be firing at idle.
__________________
94 VT1100
cignadude is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 02-12-2010, 03:00 AM   #2 (permalink)
Member
 
Join Date: Feb 2010
Location: Wisconsin
Posts: 102
Default

My '86 VT1100 had the same problem with backfiring on deceleration. I tried cleaning the carbs, adjusting the pilot screws, synched the carbs...still popped like a bugger.

Decided my best bet was to tear the carbs down a second time and give them a once-over again. During the process, I opened up the air cut-off valve and the rubber diaphragm fell out in pieces.

Did a little research and found out this valve closes the slow jet passageway when you snap the throttle shut. Long story short, I got a replacement (ebay - no longer available from Honda).....viola! Hasn't backfired since.
turntailandrunn is offline   Reply With Quote
Old 02-12-2010, 08:03 AM   #3 (permalink)
Senior Member
 
Join Date: Jan 2004
Location: Central, Minnesota
Posts: 4,796
Default

Looks to me like you need to clean the carbs.
__________________
PainterD is offline   Reply With Quote
Old 02-12-2010, 07:42 PM   #4 (permalink)
JN
Senior Member
 
JN's Avatar
 
Join Date: Oct 2007
Location: California
Posts: 1,768
Default

When you installed the Exhaust did you get a Jet kit for the carb? Or adjust the Air filter box at all? maybe even ad a K&N.

Sounds to me like your just running lean and need more gas. Some bikes you can get away with just adjusting hte mixture screw but its best to upgrade the jets as well. You need to make the (air in, gas, and air out all equal in a way) Max performance.
__________________

1997 VT1100C HondaShadowSpirit(Daily Driver)
1978 Honda xl125(Ranch Rider)
JN is offline   Reply With Quote
Old 02-12-2010, 08:34 PM   #5 (permalink)
Member
 
Join Date: Mar 2008
Location: Port Orford, Oregon
Posts: 696
Default

Quote:
Originally Posted by turntailandrunn
My '86 VT1100 had the same problem with backfiring on deceleration. I tried cleaning the carbs, adjusting the pilot screws, synched the carbs...still popped like a bugger.

Decided my best bet was to tear the carbs down a second time and give them a once-over again. During the process, I opened up the air cut-off valve and the rubber diaphragm fell out in pieces.

Did a little research and found out this valve closes the slow jet passageway when you snap the throttle shut. Long story short, I got a replacement (ebay - no longer available from Honda).....viola! Hasn't backfired since.
Congratulations on find, that the air valve was the culprit. For some reason it seems that most everyone on here either plays down that possibility or acts like they don't exist. It's assumed the problem is the pilot screw adjustment or the carbs are dirty

Of course that all changes when stock exhaust are removed.
__________________

2009
Star Raider XV19CYS

Retired ANG 1 AUG 2010
22 Years
Rick-G is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 04:50 PM.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.
Motorcycle News, Videos and Reviews
Honda Grom Forum Harley Davidson Forum Honda 600RR Kawasaki Forum Yamaha R6 Forum Yamaha FZ-09 Forum
1199 Panigale Forum Roadglide Forum Honda CBR1000 Forum Vulcan Forum Yamaha R1 Forum Yamaha R3 Forum
Ducati Monster Forum Harley Forums Honda CBR250R Forum ZX10R Forum Star Raider Forum Yamaha Viking Forum
Suzuki GSXR Forum V-Rod Forums Honda Shadow Forum Kawasaki Motorcycle Forum Star Warrior Forum KTM Duke 390 Forum
SV650 Forum BMW S1000RR Forum Honda Fury Forum Kawasaki Versys Forum Drag Racing Forum Ducati 899 Panigale Forum
Suzuki V-Strom BMW K1600 Triumph Forum Victory Forums Sportbikes BMW NineT Forum
Volusia Forum BMW F800 Forum Triumph 675 Forum MV Agusta Forum HD Street Forum Suzuki GW250 Forum
Yamaha Motorcycles Victory Gunner Forum Honda Vultus Forum