Alright everybody my bike backfires when idling and at low RPMs. Also I hear a pop coming from the carbs every so often. I know the popping is from the carbs because it blew a cap off of one of the carb boots. What is the first thing I should do to try to find the cause. The carbs are synced, at least they where about 1000 miles ago.
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Backfire at idle
USMC 2005 - Present
79 XS1100F -Mileage unknown - Clubman bars, aftermarket headlight and speedometer, 4 into 1 straight through exhaust, TopCat's fuse box, 1980G rear fender - Daily driver - My first Motorcycle
78 XS1100E - Rebuilt And Sold I SHOULD OF KEPT IT!!!Tags: None
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Carbs
1st, I just went through the same thing, It is most likely, carbs. The jets and ports on these are so small that any thing can cause a problem. Make sure that you remove the emulsion tubes (missed one on mine and POP POP POP Next, the wasted spark system can blow an air filter off, if all is not running right with the carbs, so start with the carbs, they can be a PITA on these bikes, and thanks for your service Marine
Originally posted by mmaddix View PostAlright everybody my bike backfires when idling and at low RPMs. Also I hear a pop coming from the carbs every so often. I know the popping is from the carbs because it blew a cap off of one of the carb boots. What is the first thing I should do to try to find the cause. The carbs are synced, at least they where about 1000 miles ago.1979 XS1100 Special (Mad Max, OEM) Current
1980 XS1100 Special
1990 V Max
1982 KZ750 LTD Twin
1986 700 FZR Yamaha Fazer (faster then expected)
1979 XS750 Special (my 1st Special)
1974 CB750-Four
Past/pres Car's
1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8
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Check your valves, a too-tight valve can cause backfiring issues. Look at your cam timing while you're in there. But OEM is probably right, you'll need to pull the carbs and go through them, these things can plug up at the drop of a hat...Fast, Cheap, Reliable... Pick any two
'78E original owner - resto project
'78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
'82 XJ rebuild project
'80SG restified, red SOLD
'79F parts...
'81H more parts...
Other current bikes:
'93 XL1200 Anniversary Sportster 85RWHP
'86 XL883/1200 Chopper
'82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
Cage: '13 Mustang GT/CS with a few 'custom' touches
Yep, can't leave nuthin' alone...
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Originally posted by XS1100_OEM4ME View Postand thanks for your service Marine
Originally posted by crazy steve View PostCheck your valves, a too-tight valve can cause backfiring issues. Look at your cam timing while you're in there.
Thanks again fellow members.USMC 2005 - Present
79 XS1100F -Mileage unknown - Clubman bars, aftermarket headlight and speedometer, 4 into 1 straight through exhaust, TopCat's fuse box, 1980G rear fender - Daily driver - My first Motorcycle
78 XS1100E - Rebuilt And Sold I SHOULD OF KEPT IT!!!
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This might be helpful
http://www.zrxoa.org/forums/showthre...an-carbs-(PICS
Not all carbs are the same, but they all need cleaned to the complet degree1979 XS1100 Special (Mad Max, OEM) Current
1980 XS1100 Special
1990 V Max
1982 KZ750 LTD Twin
1986 700 FZR Yamaha Fazer (faster then expected)
1979 XS750 Special (my 1st Special)
1974 CB750-Four
Past/pres Car's
1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8
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For help cleaning the carbs, look up the thread titled "Carb Cleaning 101" by Wildkat.
Tuning, meaning a lean condition can also cause the popping your describing as well. So it coul dbe as simple as another 1/4 turn or so on the mixture screws.Life is what happens while your planning everything else!
When your work speaks for itself, don't interrupt.
81 XS1100 Special - Humpty Dumpty
80 XS1100 Special - Project Resurrection
Previously owned
93 GSX600F
80 XS1100 Special - Ruby
81 XS1100 Special
81 CB750 C
80 CB750 C
78 XS750
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So when I pull the carbs to clean them I want to make sure I have the correct jets and everything in them. Which main and other jets (I forget the name of them I think they are pilot jets) should I have in there? I am ruining air pods without the airbox and I have 4 into 1 exhaust with a completely gutted muffler, nothing at all on the inside of the muffler. Is there anything else that should be checked to see if the correct size is in there for my setup?USMC 2005 - Present
79 XS1100F -Mileage unknown - Clubman bars, aftermarket headlight and speedometer, 4 into 1 straight through exhaust, TopCat's fuse box, 1980G rear fender - Daily driver - My first Motorcycle
78 XS1100E - Rebuilt And Sold I SHOULD OF KEPT IT!!!
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Well, now another light is shown on the subject. What you have is commonly referred to as straight or open exhaust, meaning no baffling for back pressure.
When you jet the carbs, you do need to account for changes from factory set up like the POD filters your using, and the non stock exhaust. There is a thread on here, some where I do not recall right off, on how to select the jetting based upon the year of the carbs, and the options you have for intake and exhaust.
I will add that very few folks have ever found success tuning for open exhaust like yours. It definitely causes a lean condition at idle and will tend to pop on decel and pop or backfire at idle.
Depending who made the exhaust your running, you may be able to get some baffling for it, like a Supertrap insert.Life is what happens while your planning everything else!
When your work speaks for itself, don't interrupt.
81 XS1100 Special - Humpty Dumpty
80 XS1100 Special - Project Resurrection
Previously owned
93 GSX600F
80 XS1100 Special - Ruby
81 XS1100 Special
81 CB750 C
80 CB750 C
78 XS750
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It was doing the same thing when I had a baffle in there. The whole reason why its Ann open exhaust is because it back fired so hard one time it blew the baffle and the end cap out of the mufflerUSMC 2005 - Present
79 XS1100F -Mileage unknown - Clubman bars, aftermarket headlight and speedometer, 4 into 1 straight through exhaust, TopCat's fuse box, 1980G rear fender - Daily driver - My first Motorcycle
78 XS1100E - Rebuilt And Sold I SHOULD OF KEPT IT!!!
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Jetting
I think this is what your looking for.
Jetting guide...
http://www.xs11.com/forum/showthread.php?t=382mack
79 XS 1100 SF Special
HERMES
original owner
http://i946.photobucket.com/albums/a...ps6932d5df.jpg
81 XS 1100 LH MNS
SPICA
http://i946.photobucket.com/albums/ad305/mack-055/2.jpg
78 XS 11E
IOTA
https://youtu.be/wB5Jfbp6SUc
https://youtu.be/RaI3WYHSuWA
Have recovery trailer and shop if you breakdown in my area.
Frankford, Ont, Canada
613-398-6186
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Exaust
Well, with "0" back presure, you got a challange on your hands, not saying it cant be done, just very hard to get it to run right that way. If you can mod it to have a super trap kinda end on the exaust pip, you can add baffels as needed till you get it running just right IMHO. Like these:
http://www.ebay.com/itm/SUPERTRAPP-4...sories&vxp=mtr
http://www.ebay.com/itm/SUPERTRAPP-4...sories&vxp=mtr
Originally posted by mmaddix View PostIt was doing the same thing when I had a baffle in there. The whole reason why its Ann open exhaust is because it back fired so hard one time it blew the baffle and the end cap out of the muffler1979 XS1100 Special (Mad Max, OEM) Current
1980 XS1100 Special
1990 V Max
1982 KZ750 LTD Twin
1986 700 FZR Yamaha Fazer (faster then expected)
1979 XS750 Special (my 1st Special)
1974 CB750-Four
Past/pres Car's
1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8
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Originally posted by mmaddix View Postwith a completely gutted muffler, nothing at all on the inside of the muffler. Is there anything else that should be checked to see if the correct size is in there for my setup?Skids (Sid Hansen)
Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.
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