Not another popping exhaust thread!! - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 30 (permalink) Old 06-12-2011, 11:21 PM Thread Starter
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Not another popping exhaust thread!!

Sorry, but I have to do it.
2004
5100 original miles
Vance & Hines Cruzers exhaust
Bike was coastered by previous owner. Also, when I took the seat off I noticed a large hose plugged with what looked like a broom stick handle with a hose clamp on it!
I seated the carb screws and backed them out 3 full turns each
Bike runs incredible but pops out of the exhaust like nobody's business at low speed deceleration or downshifting.
Bike has no vacuum leaks that I could find.
New plugs and battery
Gas is questionable though. It had 1/2 a tank when I got it. Previous owner thinks he put seafoam in the tank but couldn't recall.
I filled it with 92 octane.
A few of my buddies told me to run that tank down to nothng and put fresh gas in it and see what happens before I start tearing into the bike to figure out why it is popping so much.
Any suggestions on anything I might be overlooking?
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post #2 of 30 (permalink) Old 06-13-2011, 12:27 AM
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A exhaust leak at the gasket will cause that as well, make sure your exhaust nuts are tight. If llos the gasket is probabley shot.

Chad Falstad "Hawk"
Vroc #17649
2011 HD Ultra Classic "angel"
2001 Nomad 1500 Sold March 2012
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post #3 of 30 (permalink) Old 06-13-2011, 12:48 AM
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Quote:
Originally Posted by jgcable View Post
Sorry, but I have to do it.
2004
5100 original miles
Vance & Hines Cruzers exhaust
Bike was coastered by previous owner. Also, when I took the seat off I noticed a large hose plugged with what looked like a broom stick handle with a hose clamp on it!
I seated the carb screws and backed them out 3 full turns each
Bike runs incredible but pops out of the exhaust like nobody's business at low speed deceleration or downshifting.
Bike has no vacuum leaks that I could find.
New plugs and battery
Gas is questionable though. It had 1/2 a tank when I got it. Previous owner thinks he put seafoam in the tank but couldn't recall.
I filled it with 92 octane.
A few of my buddies told me to run that tank down to nothng and put fresh gas in it and see what happens before I start tearing into the bike to figure out why it is popping so much.
Any suggestions on anything I might be overlooking?
Who knows what he PO did, but if the coasters aren't properly sealed, a leak there will also pop on you.

FWIW, my stock pilot screws were 2.5 out on the front and 3.5 turns on the rear, so just because you're at 3 turns out doesn't necessarily mean that it's sufficient.

Try 3.25, 3.5, 3.75, etc. Once you hit 4 turns out, it's time for bigger pilot jets...

EDIT: Popping is an indication of a lean mixture. Popping on decel means it's popping when the throttle is closed...i.e. pilot circuit...ergo more turns out on the pilot screws. Oh, and ditch the 92 for 87. Keep your baseline solid w/ the fuel until you're comfortable with everything being set right before fiddling with fuel octane. And these bikes have no need for anything other than good old fashioned 87...

'98 VN750, Mustang Seat, F&S Engine Guards, Highway pegs, Pro-Tac backrest, Harley 58121-85B windshield lowers, Autometer 3391 voltmeter, ACCT to MCCT, pickup coils at 0.020", Coasters, National Cycle N2220, Vista Cruise Universal, Single Filter Ear Shave, Givi Monokey Sidebag Mounts, Givi E21 side bags, Knifemaker style turn signal relocation, helmet locks relocated.

Last edited by abyssdncr; 06-13-2011 at 12:56 AM.
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post #4 of 30 (permalink) Old 06-13-2011, 01:13 AM
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X2 to a possible exhaust leak. Check in calm air by holding a lit cigarette or piece of incense near the exhaust gasket and watching the smoke to see if it is disturbed.

The 92 octane gas isn`t helping either. By design it is harder to ignite than a lower octane gas. When you refill, use regular 87 octane, as that what the engine was designed to use. You only need higher octane gas if the engine knocks (cylinder pre ignition caused by something before the the spark plug fires, usually a small piece of red hot carbon stuck to the interior of the combustion chamber).

Gordon

1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

H-D windshield
Relocated R/R
MF-AGM battery
Fiamm Freeway Blaster horns
F&S luggage rack and engine guard
Kury Offset Hiway pegs
July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15


TOP TEN THINGS A NEW RIDER/OWNER SHOULD DO. Click on link.
https://www.vn750.com/forum/11-vn750-general-discussion/9127-top-ten-items-you-would-suggest-new-owner-do-his-new-ride.html
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post #5 of 30 (permalink) Old 06-13-2011, 08:17 AM Thread Starter
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Quote:
Originally Posted by abyssdncr View Post
Who knows what he PO did, but if the coasters aren't properly sealed, a leak there will also pop on you.

FWIW, my stock pilot screws were 2.5 out on the front and 3.5 turns on the rear, so just because you're at 3 turns out doesn't necessarily mean that it's sufficient.

Try 3.25, 3.5, 3.75, etc. Once you hit 4 turns out, it's time for bigger pilot jets...

EDIT: Popping is an indication of a lean mixture. Popping on decel means it's popping when the throttle is closed...i.e. pilot circuit...ergo more turns out on the pilot screws. Oh, and ditch the 92 for 87. Keep your baseline solid w/ the fuel until you're comfortable with everything being set right before fiddling with fuel octane. And these bikes have no need for anything other than good old fashioned 87...
Thanks! I will check it out.
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post #6 of 30 (permalink) Old 06-13-2011, 08:22 PM Thread Starter
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OK, I think I found the leak. I grabbed an incence stick and lit it up and went all around the bike checking out the smoke. It was undisturbed until I got to the brake side of the exhaust where it bolts to the front jug. The smoke became a stream drawn directly into where the exhaust bolts on.
The bolts are tight so I assume I need new metal O-ring gaskets.
Where do I get them quickly? I am hoping the local Kawasaki dealer has them in stock. My bike has Vance & Hines Cruzers exhaust on it but that shouldn't make any difference in the gasket. What do you guys recommend?
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post #7 of 30 (permalink) Old 06-13-2011, 08:28 PM
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Harley Dealership.

Read this:

https://www.vn750.com/forum/showthread.php?t=1144

'98 VN750, Mustang Seat, F&S Engine Guards, Highway pegs, Pro-Tac backrest, Harley 58121-85B windshield lowers, Autometer 3391 voltmeter, ACCT to MCCT, pickup coils at 0.020", Coasters, National Cycle N2220, Vista Cruise Universal, Single Filter Ear Shave, Givi Monokey Sidebag Mounts, Givi E21 side bags, Knifemaker style turn signal relocation, helmet locks relocated.
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post #8 of 30 (permalink) Old 06-13-2011, 08:47 PM Thread Starter
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My only problem is that the nearest Harley dealership from me is 30 miles away in the opposite direction from where I work.
There is a Kawasaki Dealership 3 blocks from my work.
I need to have the bike inspected by Saturday so I need to replace this gasket in the next 2 days.
If I am going to have a problem with the Kawasaki gaskets I will wait until I can get the Harley part # 17048-98 but I read every post about crush gaskets on this forum and it seems that 1/2 the people use Harley and the other 1/2 use Kawasaki for the V&H Cruisers.
I only want to do the job once and do it correctly though.
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post #9 of 30 (permalink) Old 06-13-2011, 08:57 PM
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Originally Posted by jgcable View Post
My only problem is that the nearest Harley dealership from me is 30 miles away in the opposite direction from where I work.
There is a Kawasaki Dealership 3 blocks from my work.
I need to have the bike inspected by Saturday so I need to replace this gasket in the next 2 days.
If I am going to have a problem with the Kawasaki gaskets I will wait until I can get the Harley part # 17048-98 but I read every post about crush gaskets on this forum and it seems that 1/2 the people use Harley and the other 1/2 use Kawasaki for the V&H Cruisers.
I only want to do the job once and do it correctly though.
Doesn't matter which one you use, but the chances of finding one at a shop on short notice is likely better (and cheaper) at the Harley dealer than at the Kawi dealer. Make your calls and see who has one in stock. The Kawi part number is also in that thread.

'98 VN750, Mustang Seat, F&S Engine Guards, Highway pegs, Pro-Tac backrest, Harley 58121-85B windshield lowers, Autometer 3391 voltmeter, ACCT to MCCT, pickup coils at 0.020", Coasters, National Cycle N2220, Vista Cruise Universal, Single Filter Ear Shave, Givi Monokey Sidebag Mounts, Givi E21 side bags, Knifemaker style turn signal relocation, helmet locks relocated.
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post #10 of 30 (permalink) Old 06-13-2011, 09:02 PM Thread Starter
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Quote:
Originally Posted by abyssdncr View Post
Doesn't matter which one you use, but the chances of finding one at a shop on short notice is likely better (and cheaper) at the Harley dealer than at the Kawi dealer. Make your calls and see who has one in stock. The Kawi part number is also in that thread.
I didn't see the Kawi part number in that thread. I saw a part number for a complete gasket set for $105.00
I just need 1 exhaust gasket. Thanks...
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