Moderate decel popping
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Tourer
Joined: Jan 2010
Posts: 374
Likes: 5
From: Overland Park, Ks
Moderate decel popping
I've got it from 2,100RPM on down after the engine is warmed up. I'm thinking it is either intake or exhaust leak or both. How do you check for these? I tried cigar smoke but couldn't tell from that. Any ideas how to check for intake and exhaust leaks?
Thanks
Thanks
Grand HDF Member
Joined: Mar 2013
Posts: 4,922
Likes: 589
From: Running with the gators
Could be a couple of things. Exhaust leak, sure. Could even be the type of exhaust and baffle. Im getting some pop due to running a cylindrical type baffle in my Vance and Hines straight shot slip-on's. There is not much for restriction so lot's of air in there for igniting unburned fuel on decal. Or it could be you need to fine tune air fuel ratio for when you roll off the throttle. The way I understand it, when you roll off throttle, both intake and exhaust valves are open for a bit for EPA reasons and causes unburned fuel to pass through to the exhaust where if like my muffles which are open, mixes with all the air and wa la decel pop!! But dont hold me to this as law, just what I understand. Im sure if in my case I switched to Rush with a hour glass shaped baffle, I would not get decel pop in which case would be cheaper and easier than messing with running, dyno's, and all that crap. Im not looking to race the guy next to me to the next bar. I just want to enjoy the ride.
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Joined: Oct 2007
Posts: 4,108
Likes: 1,964
From: New England
Your knowledge/understanding of decel popping is suspect. To state that simply switching out parts instead of determining where and under what conditions the pop occurs by way of properly diagnosing the problem (dyno's and all that crap) is truly the amateur way of doing things.
Grand HDF Member
Joined: Oct 2009
Posts: 3,824
Likes: 603
From: Myrtle Beach SC
Simple way for intake is to spray a little ignitable substance such as carb cleaner at the intake ports while the bike is idling. If idle speed changes, the intake is suckin it in. Exhaust, check for carbon footprints around the pipe junctions.
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Elite HDF Member
Joined: Sep 2007
Posts: 4,928
Likes: 69
From: Near Myrtle Beach, SC
Most popping is due to an improper tune rather than a leak. Leaks can contribute, but it's likely your tune.
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Road Master
Joined: Jun 2010
Posts: 1,221
Likes: 4
From: Annemasse (border of Geneva-Switzerland) facing Mt-Blanc.
For spotting intake or vacuum leaks I apply isopropyl alcohol.