Popping Candy - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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\ From the radiator, through the case and out
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post #1 of 34 (permalink) Old 04-25-2016, 04:37 AM Thread Starter
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Popping Candy

Ok, so I installed a set of Harley Dyna mufflers when I got the bike and she has been popping a lot on decel since then. I tried a few things till eventually I got a pain in my ass and decided to attack the issue head on. I bit the bullet and got a complete Jardine exhaust. She is coastered.... I used the old reed valve gaskets and I found one to be leaking. I got new gaskets and now there's no leak...... Got 3 different types of exhaust gaskets (Harley, Kawasaki, and spurious). I ended up using the Kawasaki ones and there are no exuast leaks......... It's ear shaved, 'rejetted to 42/140 and the carb boots are lined up perfectly. No vacuum leaks any where. Right side carb nipple capped off properly, left petcock to carb vacuum tube repleced. Air screws turned out a whopping 3 1/4 turns!!!!!

My question is........ With this new Jardine exhaust, I was expecting some popping on deceleration but how much popping normal for an aftermarket exhaust? I am still getting some popping on decel..... About the same as the Dyna mufflers but of course it's louder.

So, how much popping is ok????
They sound amazing though lads, soooooo good!!!!

Cheers.
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post #2 of 34 (permalink) Old 04-25-2016, 07:43 AM
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Without coasters... why would there be any popping at all? Popping is from emissions feedback. Sounds to me like you ripped all of that out, though, right?

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post #3 of 34 (permalink) Old 04-25-2016, 08:08 AM Thread Starter
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Without coasters... why would there be any popping at all? Popping is from emissions feedback. Sounds to me like you ripped all of that out, though, right?

Yep....... All gone...... Coastered with new gaskets and no leaks.

I know aftermarket exhausts do pop due to ignition of unburnt fuel in the exhaust but how much popping is normal is my query........ Coz this pops quite a bit on decel. They're Jardine Rumblers, they're loud but they're not straight through pipes, they do have baffles in.
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post #4 of 34 (permalink) Old 04-25-2016, 08:27 AM
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Originally Posted by skinnylizzy View Post
Without coasters... why would there be any popping at all? Popping is from emissions feedback. Sounds to me like you ripped all of that out, though, right?

Yep....... All gone...... Coastered with new gaskets and no leaks.

I know aftermarket exhausts do pop due to ignition of unburnt fuel in the exhaust but how much popping is normal is my query........ Coz this pops quite a bit on decel. They're Jardine Rumblers, they're loud but they're not straight through pipes, they do have baffles in.
okies, so... first keep in mind ima idiot n00b ( ofeeshul and stuffs ). It you can handle that, then . . .

If the popping exists... and...
The "extra fuel" is being introduced to the tank . . . and...
It is getting enough oxygen to cook in the pipes. . .

then first thing that comes to my idiot n00b mind is that what would normally be consumed, even during deaccel is being wasted... I would start with the easiest and simplest and work my way up, and it sounds like you are the same...


If there is gas to pop, then an inadequate amount of gas is being turned into power. You checked your gaskets.. and your hoses already so...
  1. bad fuel mix
  2. spark plugs
  3. spark plug cables
  4. ignition coils
  5. pickup coils
  6. ignitor unit
  7. compression ring

Did i miss anything? prolly so.

1987 VN750 California - "Lydia"
Reupholstered leather seat w/matching lockbox.
Rebuilt battery cage
Relocated R/R
AGM battery
Murican MCCT
Redesigned Rear - LED Tag/Signals/Harness
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post #5 of 34 (permalink) Old 04-25-2016, 08:31 AM
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I think the coast enrichers can stick and cause lean popping.

Coastered and earshaved mine before the first ride. On the first rides, it popped on decel. Ran some seafoam and the popping was gone after a few rides.

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post #6 of 34 (permalink) Old 04-25-2016, 09:08 AM
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Originally Posted by Spockster View Post
I think the coast enrichers can stick and cause lean popping.

Coastered and earshaved mine before the first ride. On the first rides, it popped on decel. Ran some seafoam and the popping was gone after a few rides.
Ahhh missed that on my list...

checking the Seafoam tank and the little Seafoam pump that goes into the heads and cleans the valves...


1987 VN750 California - "Lydia"
Reupholstered leather seat w/matching lockbox.
Rebuilt battery cage
Relocated R/R
AGM battery
Murican MCCT
Redesigned Rear - LED Tag/Signals/Harness
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post #7 of 34 (permalink) Old 04-25-2016, 09:21 AM Thread Starter
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@ RoadHopper

I've got NGK Iridium plugs and a Maintenance Free battery installed and there's absolutely no drop in performance like misfiring or anything so I don't think it's an ignition problem. I wonder am I over fuelling with the air/fuel mixture screws screwed out 3 1/4????? Thanks for your input, I like your style of thinking.

Last edited by skinnylizzy; 04-25-2016 at 09:25 AM. Reason: No @
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post #8 of 34 (permalink) Old 04-25-2016, 09:24 AM Thread Starter
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Quote:
Originally Posted by Spockster View Post
I think the coast enrichers can stick and cause lean popping.

Coastered and earshaved mine before the first ride. On the first rides, it popped on decel. Ran some seafoam and the popping was gone after a few rides.

Yeah I replaced the enrichers when I did the jets....... One of them was in a really sorry state. With regards the seafoam, it's very hard to come by on this side of the pond so I have put in a rather expensive alternative, 44k by BG....... It's meant to be good stuff.
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post #9 of 34 (permalink) Old 04-25-2016, 09:48 AM
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Quote:
Originally Posted by skinnylizzy View Post
@ RoadHopper

I've got NGK Iridium plugs and a Maintenance Free battery installed and there's absolutely no drop in performance like misfiring or anything so I don't think it's an ignition problem. I wonder am I over fuelling with the air/fuel mixture screws screwed out 3 1/4????? Thanks for your input, I like your style of thinking.
Appreciate it...

simply put... i think backwards... a lot.

If the gas is not getting enough compression then its temperature will be insufficient to burn fully. So... with everything else checked... you can lead a piston to Seafoam but you cant make it drink. That would be the dead last thing to check, though, . . .

and hey... wait a sec... thats a whole 3/4 notch higher... right? Just curious, but... when was the last time you checked to make sure they are still in the same position that you left them? Screws are the playthings of gremlins.



1987 VN750 California - "Lydia"
Reupholstered leather seat w/matching lockbox.
Rebuilt battery cage
Relocated R/R
AGM battery
Murican MCCT
Redesigned Rear - LED Tag/Signals/Harness
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post #10 of 34 (permalink) Old 04-25-2016, 11:24 AM
..have a vulcan good day!
 
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Thanks .... - - I needed a good Chuckle
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'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
SilverStar Ultra 9003/HB2 H4 Headlamp, Jardine Fwd Controls,
Iridiums DPR7EIX-9 & Wires, Tuxedo Mod, Coil Mod, P/U Sensor Mod, Fork Seals,
Splines Lubed - 11/4/2012 - MF AGM Battery
Additional Flashing LED Brake Light on Trunk
Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
...have a vulcan good day!
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