Yet another problem
07-25-2011, 08:22 PM
#1
Jack of all Master of non
Superstock
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Join Date: May 2011
Location: Jacksonville,fl
Posts: 297
Yet another problem
ok here it is,
i just put my bike back together after tearing it down to check some things. i test rode it around the neighborhood and things work just fine.. today i took it for its first ride and i was impressed. it has all its power and more so than before but now around 2k with steady throttle it pops and back fires in the carbs and most of all on decel it backfires like crazy, so much in fact that it shoots a flame out of the tail pipe.....
Am i too lean or too rich, it does not make sense because it has all the power it should and does fine at highway speed but???????????????????????
Any Help???????????????????????
i just put my bike back together after tearing it down to check some things. i test rode it around the neighborhood and things work just fine.. today i took it for its first ride and i was impressed. it has all its power and more so than before but now around 2k with steady throttle it pops and back fires in the carbs and most of all on decel it backfires like crazy, so much in fact that it shoots a flame out of the tail pipe.....
Am i too lean or too rich, it does not make sense because it has all the power it should and does fine at highway speed but???????????????????????
Any Help???????????????????????
07-25-2011, 08:44 PM
#4
Senior Member
MotoGP
Join Date: Mar 2007
Location: Phoenix, AZ
Posts: 3,132
Disable PAIR & sync the carbs..
I can get some flaming backfires on deceleration if I want to, but I don't have the 2k pops.. I know I am a tad lean. (exhaust swap without carb adjust and it runs perfect at altitude is how I know)
You can test lean/rich by using the choke.. If a little choke helps you are lean, if it makes it worse you are rich.
edit: and listen to our resident carb guru: 8541Hawk
I can get some flaming backfires on deceleration if I want to, but I don't have the 2k pops.. I know I am a tad lean. (exhaust swap without carb adjust and it runs perfect at altitude is how I know)
You can test lean/rich by using the choke.. If a little choke helps you are lean, if it makes it worse you are rich.
edit: and listen to our resident carb guru: 8541Hawk
07-26-2011, 04:18 AM
#5
Jack of all Master of non
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Join Date: May 2011
Location: Jacksonville,fl
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pair is out already and carbs were synced up.
vacume is what i was thinking also because it was working fine and the all of a sudden it started doing this but looking around i cant find anything. also thinking the carbs came out of sync somehow....... my choke has been removed and sealed off
vacume is what i was thinking also because it was working fine and the all of a sudden it started doing this but looking around i cant find anything. also thinking the carbs came out of sync somehow....... my choke has been removed and sealed off
07-26-2011, 09:55 AM
#9
Jack of all Master of non
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Join Date: May 2011
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i took the threaded end off the choke removed the spring and needle from the cable. put the needel and spring back in the threaded part and then caped it off with air line plug...
Choke in FL is pointless in the summer or even winter for that matter.
i just need to know why it is backfiring so bad and sputtering around 2k
Choke in FL is pointless in the summer or even winter for that matter.
i just need to know why it is backfiring so bad and sputtering around 2k
07-26-2011, 10:38 AM
#10
Banned
MotoGP
Join Date: Aug 2007
Location: Lake View Terrace, CA
Posts: 5,942
I've never heard of anyone doing that with the choke but if it ran fine and now gives you problems, I would still say it sounds like a vacuum leak.
Do you have the fittings installed for sync'ing the carbs? Did you loose one of the caps? Are the isolators (the rubber bits the carbs mount in) in good shape with no cracks and the clamps tight? Are all the vacuum line installed and in good shape with no cracks?
If you don't find any problem with these things then check the way you plugged the choke.
Do you have the fittings installed for sync'ing the carbs? Did you loose one of the caps? Are the isolators (the rubber bits the carbs mount in) in good shape with no cracks and the clamps tight? Are all the vacuum line installed and in good shape with no cracks?
If you don't find any problem with these things then check the way you plugged the choke.
07-26-2011, 11:23 AM
#11
Senior Member
SuperBike
Join Date: Dec 2005
Location: South Lake Tahoe, CA, USA
Posts: 1,689
Backfiring is due to unburned fuel in the exhaust - which in turn is caused by a lean condition (the lean mixture does not ignite in the cylinder). Misfiring at 2-3k is also a sign of a lean condition.
A vacuum leak in the fuel enrichment (choke) valve sounds like a likely place to look, since it ran fine before you changed it and have not located other vacuum leaks. Excess air is getting in somewhere.
A vacuum leak in the fuel enrichment (choke) valve sounds like a likely place to look, since it ran fine before you changed it and have not located other vacuum leaks. Excess air is getting in somewhere.
07-27-2011, 06:31 AM
#12
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Thanks. Hawk I found the problem I think. The cap I put on the Carb that went to the pair valve when I removed the pair feel off some how. So I glued another one back on it and it sounds great. I may have to sync the Carb again but I funk I found my problem...... thanks for the direction
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