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Ive noticed more and more popping on decel lately. When i first did the build maybe 6 months ago it never popped. Then i heard it once in a while and now it seems more pronounced then it had been. Whenever I take it to 4500+ rpms and let it decel it gives me some pops and i do that everyday :thumbsup: . Can this be a result of the rush slippons breaking in/burning off/loosing backpressure for whatever reason? Or is it a tuning issue? It seems to me it isnt a tuning issue because: Its the same map as I had before with no popping, And if it can be tuned out thats great but if it is the slippons and they wear/change more do you then need to change the tune again? Or am I totally off base and it has nothing to do with the mufflers?
Ah, and before Tot reads this and gives me a ration of ---- let me add that I will get this thing properly tuned one of these days soon hehe !!!!
 

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pop

check for loose exhaust connections, Also is the air getting better now that summer is going bye bye ??? So now its running leaner ??:hmmm:
 

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Intake

Might also check your intake manifold seals for an air leak - leaning it out on de acceleration. Could try spraying carb cleanerat the mating surfaces between the head and intake - see if it changes at idle.

Just aTHOUGHT
 

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The dreaded decel pop

The guys above are definately on the correct track. If you bike didn't have decel pop before, then chances are there is an air leak in the exhaust or in the intake some where. On the intake side, I spray WD40 on all of the mating surfaces. If you detect an increase or a surge in idle speed, then there is definately a leak where you just sprayed, as long as the WD isn't getting into the air cleaner. So be careful where you point the spray. If the decel pop does not go away, then chances are, its one of the exhaust connections, either at the head/exhaust pipe flange, or at a pipe/muffler interface, etc.. Sometimes an exhaust system with modified or more open baffles, or no baffles will also allow the dreaded decel pop to occur. In any event, good luck-2$en#e-
 

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Rush/EPI just told me that they use a thicker gauge steel in their mufflers, and that you need to "overtighten" the muffler clamp to get them to seal, and that you should not re-use the HD Torca clamps.
This seems to be true, for I discovered that both were leaking.
Now though, I need to get another new muffler clamp, I broke one trying to get it tight enough to seal.:duh?:

But, as the others have said, it could be intake seals, an exhaust leak elsewhere in the system, or a EFI/injector issue.
 

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I am getting fluttering on decel and some loud pops now and than..
How do I check if there is a leak at the head?
 

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jonno said:
I am getting fluttering on decel and some loud pops now and than..
How do I check if there is a leak at the head?
Take a 18'' or so piece of fuel line or oil line or even a length of old garden hose, put one end to your ear and the other end at the exhaust port...if you have a leak you will know it .....you will hear a ticking noise from the exhaust escaping. You can also use this method around the cross over to see if the gasket is bad and also for intake leaks. The hose is like a stethoscope for air movement.
 

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This is a very common problem that " Zippers" has noticed with users of
the Thundermax together with the Rush Slip-On mufflers. The
mufflers are the main reason.

Seems as the left pipe sucks air upon decel and effects the wide band sensor.

The quick fix is a insert type washer, that can be home made or purchased
from "Zippers" to slow down the amount of air the left muffler sucks back
upon decel. I think they charge about $4.00 for this item.

Geezer
 

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If it's not an air leak it could be that with the cooler fall air your A/F mixture is changing just enough to induce the popping, I see that with mine at different temps and altitudes.
 

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Just checked and there is absolutely no leaks by the heads..I am figuring she is just a bit lean and could use a good dyno tune..
 

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jonno said:
Just checked and there is absolutely no leaks by the heads..I am figuring she is just a bit lean and could use a good dyno tune..

That could very well be it. I've had decel pop on 4 different builds(same engine, just different components) and cured the popping on 3 of them by taking fuel away at %0 throttle with my PC.

This newest one has been a chore. I've rebuild my exhuast and intake. Has cured the worst of it but it's still there on occasion.

I will be getting the T-Max at some point. Hopefully that will cure it for me.
 
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