Need help,carb backfiring on 98 cbr 919rr - Honda Motorcycles - FireBlades.org
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post #1 of 7 Old 03-16-2013, 11:04 PM Thread Starter
 
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Need help,carb backfiring on 98 cbr 919rr

So i just got done rejetting my 98 cbr919rr,and hooked it all back up and was about to use the motion pro carb synchronizer,I had the fuel line hooked up to a fuel funnel and had the motion pro set up,started the bike and let her run,she started to run pretty high into 3500-4000 rpms and the settled down to 1300 rpms,and she sounded all right just a little out of sync but before i could start the sync process she started to backfire from the #3 carb,I shut her down and let her settle while i tried to figure out why,couldnt figure anything out so i restarted her and she did the same thing,high rpm then right back to low 1000s rpms,then she backfired once again from the #3 carb,i could really use some advice on this one,kinda stumped on why shes doing it since she does it periodically while idling instead of continuously backfiring.
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post #2 of 7 Old 03-17-2013, 10:36 AM
 
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Re: Need help,carb backfiring on 98 cbr 919rr

Are you doing this with the airbox off? Don't.

Please go make a welcome thread with pics of your bike / wife / dog
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post #3 of 7 Old 03-17-2013, 11:32 AM Thread Starter
 
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Re: Need help,carb backfiring on 98 cbr 919rr

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Originally Posted by amorti View Post
Are you doing this with the airbox off? Don't.

Please go make a welcome thread with pics of your bike / wife / dog

yes i took the airbox off.Is there a reason why its bad to do so when your syncing the carbs
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post #4 of 7 Old 03-17-2013, 12:58 PM
 
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Re: Need help,carb backfiring on 98 cbr 919rr

The carbs rely on getting the right amount of air to the fuel which is pre-metered by the jets. With the airbox off they won't get that. No CV carbs will run right without an airbox or rejetting.

Put it back on and try again.

If you don't know this, are you confident to balance the carbs?
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post #5 of 7 Old 03-17-2013, 2:54 PM Thread Starter
 
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Re: Need help,carb backfiring on 98 cbr 919rr

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Originally Posted by amorti View Post
The carbs rely on getting the right amount of air to the fuel which is pre-metered by the jets. With the airbox off they won't get that. No CV carbs will run right without an airbox or rejetting.

Put it back on and try again.

If you don't know this, are you confident to balance the carbs?

yes i'm confident enough,I'll try it with the airbox off and let you know
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post #6 of 7 Old 03-17-2013, 3:50 PM
 
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Re: Need help,carb backfiring on 98 cbr 919rr

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Originally Posted by twiztedtatz77 View Post
yes i'm confident enough,I'll try it with the airbox off and let you know
Try with it back on and let us know

PS, not joking about the intro thread and pics, it's only good form to introduce yourself
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post #7 of 7 Old 03-18-2013, 5:20 AM
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Re: Need help,carb backfiring on 98 cbr 919rr

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Originally Posted by twiztedtatz77 View Post
yes i'm confident enough,I'll try it with the airbox off and let you know

At least put the airbox back on and see if that fixes the problem?

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