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Discussion Starter · #1 ·
I've been working on this problem for a while and just about to give up on it and say it's just the way it is. But I'm having trouble doing that so here it is...

Dual HMF
springs trimmed, needles shimmed,slides plolished and pilots 2.5 out tuned w/ LM2 13 at WOT
vented air box w/ k&n filter
cr8 spark plugs w/boot mod

Front cylinder runs smooth but I get a popping from the rear when I'm running slow at 1/4 throttle. At WOT it pulls great all the way through
and I don't get a decel popping like I was. But its just the popping when
I'm at a steady 1/4 throttle

This popping drives me crazy! How do I get rid of it or is this just the way it is?

Any ideas are greatly appreciated. Thanks Lonnie
 

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Have you blown out the pilot on the rear carb to be sure it isn't clogged at all---Or better yet put a new one in or switch the 2 and see if rear still does it

Could it be something in the float on the rear????

Have you tried 2 shims on the rear needle instead of one.

Have you tried opening the a/f screw more in the rear.

Kenny
 

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Have you blown out the pilot on the rear carb to be sure it isn't clogged at all---Or better yet put a new one in or switch the 2 and see if rear still does it

Could it be something in the float on the rear????

Have you tried 2 shims on the rear needle instead of one.

Have you tried opening the a/f screw more in the rear.

Kenny
1/4 throttle is definatley the pilot circuit.
 

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Discussion Starter · #4 ·
Have you blown out the pilot on the rear carb to be sure it isn't clogged at all---Or better yet put a new one in or switch the 2 and see if rear still does it

Could it be something in the float on the rear????

Have you tried 2 shims on the rear needle instead of one.

Have you tried opening the a/f screw more in the rear.

Kenny
I have blown out the pilots but I haven't switched them.

It seems to me like it's' getting plenty of fuel

I'm afraid if I put two shims under the rear needle i'm going to be too rich??

it idles right now at 10.5-11

I'll try replacing or switching the pilots.

Thank you! Lonnie
 

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Discussion Starter · #5 ·
Tried switching pilots and the popping remained. So I turned the rear pilot 1/4 then full turn got black smoke out of the rear cylinder but popping remained. So it's back to 2.5

It almost sounds like it's missing but I've put new plugs in it so I wouldn't think it would be that. Could different plugs make a differance?

When I get some more time I'll check for exhaust leaks again. But there again i've put new gaskets in and made sure it was tight?
 

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Discussion Starter · #6 ·
I read on a previous thread that it could possibly be the cdi? I run a dynatech fs. Has anybody had trouble like this ???
 

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put the stock cdi in and it will probably go away that is how mine started then got worse after fighting with the carbs changed cdi's and it was fine
 

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Discussion Starter · #8 ·
Your probably right. That always happens you spend the money trying to do things(advance timing)the easy way and ends up screwing(the nice word) things up.:rolleyes:

I'll try it thanks Bubba!
 

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Keep us posted hope that is a easy fix how old is the cdi..I would never buy a CDI on stock bike when the degree key works better and less money heck i am back to running my stocker on my bike
 

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Discussion Starter · #10 ·
About three months old. I'll keep you posted. I'll just put in some more wrench time and get the key if this works.
 

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Discussion Starter · #11 ·
Plugged in the stock CDI and STILL doing the same thing. So..... I'll know more this weekend when I can spend some more time on it.

Thanks for the ideas and replies.
 

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Try new plug wires.

Or maybe your rear carb spring is broken. Check the slide and rubber diaphram.
 

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I had this same problem......... with my wifes bike changed main jets out and it started doing it left it alone she started asking me to fix but she instructed me along time after the aftermarket pipe and jets that was all the mods she would let me do to the bike so be it walked away from it....... now its you need to fix it ok so I swapped out #40 pilots for the #42 and set the air fuel mixer and I did not notice it at all..... My Moms bike had a problem close to that but it had no power at all Dad took it back to the shop cause they had it only 2wks and the pilot was full of stuff not sure what it was they never did state what it was....
 

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Discussion Starter · #14 ·
Sorry just received power back after 5 days! We had a major ice storm here.

Camo, I have replaced the plug wires w/ Vens modded wires and I was just in the carbs and I do make sure that every thing is right with the diaphram when I put it back. But I'll check to make sure. Spring are new and slides are shiney!:D
 

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My buddy had the SAME problem... It took a lil research on here but it ended up being the choke stuck after putting the carbs back on. It was only stuck open a hair and it did this EXACT thing. Fixed that and it ran perfect. Hope its as simple as that. If you search on here about a sticking choke you can find the thread and there was a pic of it with a red circle showing the choke. FYI he was about to give up too... lol :) I will be real curious if this is your problem so keep us posted.
 

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Discussion Starter · #16 ·
Thanks runinines. I'll check that out this weekend. Hopfully that will be it. Would be nice.

I'll let you know.
 

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Discussion Starter · #18 ·
A mix of the choke stuck and running rich. Fixed the choke and working on the rich problem. Well rich in the mid but lean on the top so it could be a little of both
 

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Tried synchronising those carbs so they both open at the same time, not one slightly after the other?
 
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