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Discussion Starter · #1 · (Edited)
My sig is currently correct---It has been backfiring for quite a time now---Have tried various jetting combos---Have put in #42 pilots---Just adjusted the valves---Found exhausts to be ok, (an 8 slides in easily), but the intakes were tight as I could not get a 6 in them---So adjusted both front and rear intakes at a tight 6---Bike started and ran fine but still same exact back firing---It was mostly on decel at wot in the beginning but is now in mid and low range.

Have Tried So Far

Adjusted Valves
Checked--No leaks in exhaust
New header gaskets (sealed no leaks)
Tried 2 sets of duals (both with new packings)
Sprayed starting fluid around intakes
Covered 4 holes in air box lid
New spark plugs and plug wires
Tried adjusting idle up and down
Examined choke plungers-both are closing
3 turns out on A/F screws
182 front and 185 rear
Tried both #40 and #42 pilots
1 shim on both needles
Checked slide vent tube it's open
Tried 2 shims on needles
Tried 185 main if the front

Grrrrrrrrrrr---I am at a loss on this one

Kenny
 

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Discussion Starter · #3 ·
Check for exhaust leaks.
Yeah I had Yoshi's on and took them off and put on a new set of Pro Circuits that are tight and sealed and it actually backfires worse with the new ones---The Yoshi's have a mixer pipe and the Pro's go straight threw on each side.

Grrrrrrrrrrrrrrrrrr:pissed::pissed:

Kenny
 

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Back the air screws out on the carbs to 3 turns. Turn them all the way in, then turn them out 3 full turns. That cured mine with the Pro Curcuits.
 

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Discussion Starter · #5 ·
Back the air screws out on the carbs to 3 turns. Turn them all the way in, then turn them out 3 full turns. That cured mine with the Pro Curcuits.
Look at my sig---Already did that

Grrrrrrrrrrr:pissed::pissed:

Kenny
 

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Kenny, have you tried adjusting the idle? Anytime you make jetting changes, especially the pilot jets, it's a good idea to adjust the idle. With 40 pilots in there, if you slow the idle down a bit, it should help/eliminate the popping on decel. I know it worked for me. I have tried all the way up to 48 pilots but it wouldn't idle unless the idle screw was maxed out. It also didn't run cleanly when on the throttle. So I started to work my way back down and the lower I went with the pilots the faster the idle got, but the more it popped on decel. I found if I slowed the idle down as well, the popping went away. Leave the 40's in there, and try adjusting the idle. Couldn't hurt.
 

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ok--we are backfireing on decell
mostly higher rpms but as of late thru the decell band.
Off the throttle
I had to run three shimms on my stock set up with pro circs.
May wanna try that.
Also--go over your coils/wire connections
plug to boot/boot to wire/wire to coil
Just shooting possibilities---I`ll think more when my head stops hurting:p
 

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Discussion Starter · #8 ·
RiceBurner---Thanks for the input---I tried turning the idle down---It started cold at about 11 and as it heated up climbed 12, 13 and settled at between 13-14 warm---So while warm I turned it to 12 still same and then to 11, (while warm) it did seem a little better but would die out and stall between 10 and 11?????

DVader---Don't hurt your head over this:p---But if it's in the wires wouldn't it show up on pulling as well as decel??

Kenny
 

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i have posted it before but a friend had a popping and it turned out being a stuck choke on one side. is it coming out of one side and not the other? we pulled the carb open and looked to see one side stuck open (a very lil bit). just a thought. good luck
 

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I'm having a VERY similar problem on my bike.. It's an 840 I just got back from Glenn.. He couldn't tune it for me because his dyno was down.. So now I have to tune it myself, and I'm still learning.. Ive got 155 mains and 42 pilots and dynojet needles in it, my screws are at 3 turns and it's running about 12 to 13..But after holding it full throttle, on decel it backfires and cackles.. On my LC1 I keep getting crazy numbers, jumping around alot.. Even when holding it at a steady throttle running about 60mph.. What could cause this ?? And Kenny, I'm not rying to jack your thread or anything bud..:D Just trying to get some help for a very similar problem.. Thanks
 

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Discussion Starter · #11 ·
i have posted it before but a friend had a popping and it turned out being a stuck choke on one side. is it coming out of one side and not the other? we pulled the carb open and looked to see one side stuck open (a very lil bit). just a thought. good luck
How can that be---I'm holding a set of stock carbs in my hand---Both butterflies open and close together---I put a toothpick in one so it couldn't close all the way and both stayed open the same distance---Plus the butterflies don't seal when closed as you can hold up to the light and see through all around both edges:hmm::hmm:

Kenny
 

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i have posted it before but a friend had a popping and it turned out being a stuck choke on one side. is it coming out of one side and not the other? we pulled the carb open and looked to see one side stuck open (a very lil bit). just a thought. good luck
How can that be---I'm holding a set of stock carbs in my hand---Both butterflies open and close together---I put a toothpick in one so it couldn't close all the way and both stayed open the same distance---Plus the butterflies don't seal when closed as you can hold up to the light and see through all around both edges:hmm::hmm:

Kenny
The butterflies are not the chokes; they control the airflow to the engine, i.e. the throttle.
The "chokes" are not chokes; they are enrichener circuits and are controlled by two little plungers that open and close the enrichener circuit. As runinines has said, if a plunger sticks out a little bit, it will supply fuel when you don't want it to.
 

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Discussion Starter · #14 ·
I looked up carb parts---So is the choke---The plunger part #16016---If so seems like only way to see end of it would be open the black caps and remove the slides---Is that correct??

Kenny
 

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yes you are correct. remove them and you will be able to see if one is open more then the other. It doesnt take much at all to add more fuel when not needed. This led to a pop out of one side and not the other. It was easy to hear on a dual exhaust. but a had a long time solving this problem.
 

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Discussion Starter · #16 ·
i have posted it before but a friend had a popping and it turned out being a stuck choke on one side. is it coming out of one side and not the other? we pulled the carb open and looked to see one side stuck open (a very lil bit). just a thought. good luck
Yeah it appears to be the front exhaust---definitely is at very low rpm blips of throttle----Got the air box off and slides out and they are both closed---Am looking at it with a magnifying glass too---Darn this sounded like it might have been it---Thanks for the post though

Grrrrrrrrrrrrrrr:pissed::pissed::pissed:

Kenny
 

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i have posted it before but a friend had a popping and it turned out being a stuck choke on one side. is it coming out of one side and not the other? we pulled the carb open and looked to see one side stuck open (a very lil bit). just a thought. good luck
Yeah it appears to be the front exhaust---definitely is at very low rpm blips of throttle----Got the air box off and slides out and they are both closed---Am looking at it with a magnifying glass too---Darn this sounded like it might have been it---Thanks for the post though

Grrrrrrrrrrrrrrr:pissed::pissed::pissed:

Kenny
You dont need to take the airbox off to see the chokes. are you looking at the butterflies? or the chokes. for the chokes you take the black caps off the carbs (on the sides), take out the springs, pull the boot and slides out, and then you are able to see the chokes. two barrel looking slides. you will see both of them move when you apply the choke with teh covers off. one may not close all the way. just making sure you are looking in the right spot.
 

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Discussion Starter · #18 ·
i have posted it before but a friend had a popping and it turned out being a stuck choke on one side. is it coming out of one side and not the other? we pulled the carb open and looked to see one side stuck open (a very lil bit). just a thought. good luck
Yeah it appears to be the front exhaust---definitely is at very low rpm blips of throttle----Got the air box off and slides out and they are both closed---Am looking at it with a magnifying glass too---Darn this sounded like it might have been it---Thanks for the post though

Grrrrrrrrrrrrrrr:pissed::pissed::pissed:

Kenny
You dont need to take the airbox off to see the chokes. are you looking at the butterflies? or the chokes. for the chokes you take the black caps off the carbs (on the sides), take out the springs, pull the boot and slides out, and then you are able to see the chokes. two barrel looking slides. you will see both of them move when you apply the choke with teh covers off. one may not close all the way. just making sure you are looking in the right spot.
Yuppo the Hippo---That's what I'm looking at but they are both closing like they should, (wanted the box off to see really clearly and to look at the intakes too)----I sprayed a little carb cleaner on the choke pump barrels hope that doesn't do anything negative---Oh well back to trying to figure it out.

Kenny
 

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I just let mine pop:lol:. When I put my HMF's on mine, it popped realy bad. Turned out the head pipe was too long and didn't let the gasket seal. I cut them off shorter and it helped alot. It still crackles alittle when it's slowing down, but doesn't bother me. I just replaced my choke cables and pungers. Mine were sticking pretty good. I think that helped me too.

Have you checked that your slide vent is clear?? It is the uncapped tube that hangs down on the clutch side of the V.
 

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Discussion Starter · #20 ·
I just let mine pop:lol:. When I put my HMF's on mine, it popped realy bad. Turned out the head pipe was too long and didn't let the gasket seal. I cut them off shorter and it helped alot. It still crackles alittle when it's slowing down, but doesn't bother me. I just replaced my choke cables and pungers. Mine were sticking pretty good. I think that helped me too.

Have you checked that your slide vent is clear?? It is the uncapped tube that hangs down on the clutch side of the V.
Yeah I blew through that tube and it was fine---My header pipes are sealed good---Band new gaskets and they fit perfectly--nothing there

Kenny
 
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