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Discussion Starter #1
Hey all, I'm from Greenville, S.C. I just got a 96 VN750, it really is a great bike. Just had a question about the popping, I tried the marbling trick but there really was no change. Is there a way to get the bike back to factory quality, maybe rebuild the clean air system on the bike, or the carburetor? I would imagine that it would not be that detailed but I really have no idea. Any help would be greatly appreciated. Also if I were to rebuild/modify the bike in order to get rid of all the popping, what would it entail and about how much would it run me?
 

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Not my trick, but take a lit cigerette or incense stick and run along the exhaust pipes by the engine and anywhere else theres a seam and see if the smoke is disturbed, could have an exhaust leak somewhere causing the popping..
 

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CWO3 Navy (Retired)
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If it's popping that much you most like have a leak at the manifold. Buy new Kawasaki OEM Gaskets and install them. DO NOT use the Harley gaskets, they are not the same outside diameter and will slip when you install them creating a leak. The smoke trick G3PO suggested works. Look for my post on here too on Marbling, Coastering and more....It worked for me just great!
 

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Discussion Starter #4
Thanks!

Thanks I will order the gaskets today. Does anyone know where to buy aftermarket seats or radiator chrome covers?
 

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These bikes are poppers to begin with, as the reed valves get carboned up pretty quickly and cause excessive popping on deceleration. If the marbling trick didn't solve it, (it doesn't eliminate the rumbling, but kills the excessive backfiring) then you have a leak like everyone above has already said. Unburned fuel vapors are going to get past the combustion chamber and into the exhaust and if they come in contact with fresh air, you'll get backfiring. The exhaust gaskets might be the problem or it could be other areas where there are connections in your exhaust, or even holes rusted through on the under side of the exhaust system. If you haven't already, shoot some PB Blaster on the exhaust manifold cap nuts to get them soaking. Otherwise you might have trouble getting them off and even snap off one of the studs they are screwed onto. PB Blaster will soak through and eat the rust that glues them together! Give it a soak a day or two before you plan to pull them and replace the gaskets, then soak it again the day you do the work. It also helps to warm up the bike before you start removing the cap nuts. Sucks to work on hot exhaust, but it is best for the nuts... Good luck!
 

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Discussion Starter #6
Does any one know the part number for the exhaust gaskets? And possibly a good website to order from?

Thanks,

Hutch750
 

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Hey Hutch, I don't know this for a fact as I haven't had both types to compare side by side, but I read either here or on the Kawasaki forum that the KAW crush gaskets are actually a bit thinner than the Harley gaskets. Apparently the Harley gaskets are slightly smaller in diameter than the KAW gaskets! I bought the Harley gaskets and didn't have any problem with them shifting out of place and they sealed fine, no popping. But, I know of a couple different folks here who have used the KAW gaskets and they had some leaking. I suggest that if you go with the KAW gaskets that you grab a hand full of washers and put at least one under the acorn nuts so you can make sure you don't bottom out the nuts on the stud.

The KAW gaskets: part # 11060 bikebandit.com

The Harley gaskets: part #17048-98 your local Harley dealership
 

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Hutch, go to this page: http://www.bikebandit.com/houseofmotorcycles/kawasaki-motorcycle-vulcan-750-vn750a15-us-1999/o/m4537
and scroll the categories down til you see Mufflers, click on the mini muffler pic and it will load the exhaust info. You'll see the crush gasket in the photo and the parts list below, where you can order them directly. I believe KAW uses the same gaskets on a huge number of bikes and you could probably get them at your local KAW dealership too.

It is the same gasket used on my 02 1500 classic, and I also checked the 06 1600 Classic, same gasket. Probably readily available at a KAW shop.
 

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Linkmeister Supreme
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Welcome to the Vulcan madness Hutch. You are finding out why this is such a great place for vn750 owners. Check the link below too.
 

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Discussion Starter #12
So I replaced the exhaust gaskets but I am still getting the popping. At first there was no popping at all, but after a couple minutes of warming up it started back again. I also noticed that the front cylinder exhaust was really dirty compared to the back, could this mean I have a head gasket leak? If so how hard is it to replace it? Or what is the average cost to have it replaced? And could this be the source of the popping?

Thanks,

- Hutch
 

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Did you ride it some? Usually you need to ride the bike for a while and then re-torque the acorn nuts. If you used the KAW gaskets, you might need to put some washers on the posts and put the acorn nuts over them and re-torque.
 

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Discussion Starter #14
I have not had time to ride it any, but I will after work today. I did put some washers under the acorn nuts as you suggested earlier. - Thanks by the way! How tight do the nuts need to be? I would hate to strip anything.

Thanks,

- Hutch
 

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Discussion Starter #16
I think I have fixed the popping! Only went riding for about 20 minutes today so I will have to check later on to see if it comes back but for now there is not a bit of popping! The thing that I think finally did the trick was re-torquing the acorn nuts and then I upped the idle to about 1100 RPM, it was just way too low, it was idling around 400 RPM before. So if this did fix the problem for good, in total I turned out the air-mix screws to about 3 turns, marbled, replaced the exhaust gaskets, and upped the idle. Also now as an added benefit there seems to be more power to the bike. Thanks Fergy for all the help, I really appreciate it.

- Hutch
 

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I think I have fixed the popping! Only went riding for about 20 minutes today so I will have to check later on to see if it comes back but for now there is not a bit of popping! The thing that I think finally did the trick was re-torquing the acorn nuts and then I upped the idle to about 1100 RPM, it was just way too low, it was idling around 400 RPM before. So if this did fix the problem for good, in total I turned out the air-mix screws to about 3 turns, marbled, replaced the exhaust gaskets, and upped the idle. Also now as an added benefit there seems to be more power to the bike. Thanks Fergy for all the help, I really appreciate it.

- Hutch
Hey Ferg,
Sound familiar :)
 
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