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Old 10-08-2009   #1
KYRider
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Vulcan 1500 backfire, popping, and cracking pipe problem...

In the past several weeks the motorcycle has started to backfire, pop, and crack from the top pipe on the motorcycle. The motorcycle is a 2004 Kawasaki Vulcan 1500 Classic (VN1500E7), carburetor, with Vance and Hines Classic II pipes. The V&H Classic pipes were added about two years with rejetting the carburetor and the motorcycle has been riding great from that time. Absolutely no backfire, popping, or cracking.

Over the last several weeks I have put in new spark plugs, checked all fuses, put in new exhaust header gaskets, which the gaskets were using OEM Kawasaki gaskets. Never had a problem until three weeks ago. I checked the bolts on the exhaust and they were tight (as never had any of these problems in the past). I installed the Harley-Davidson screaming eagle exhaust gaskets (PN: 174098-98) from the OEM Kawasaki exhaust gaskets, and and there is not much different unless it is my easing on the throttle to try to avoid the popping and cracking.

I checked and tighten up the bolts on the pipes, not sure if I can tighten them any tighter. Still the pipes pop, crack, and backfire. I found it is only the top pipe where it backfires, unsure if this helps or indicates a particular problem. Some friends that I ride with mentioned that when the motorcycle pipes pop, cracks, and backfires, it is from the top pipe. I also removed and put back in the marbles in the reed valve as mentioned on Gadget's web site. I had the marbles in there just as long as the pipes were changed on the motorcycle.

After more researching and talking to other riders that have worked or have knowledge of such problems, the problem may be the manifold intakes gaskets. The backfire, popping, and cracking is only on the top pipe, the rear cyclinder, and possibly the one or both gaskets are leaking air.

Hopefully over the day or two I have the time to check the manifold intakes gaskets to see if they need to get replaced.

I'm not mechanic, however, I have been taking the time to research this problem and trying to figure out how to remove the carb from the motorcycle. This is all new to me and seems interesting, just with I knew more about the carb in removing it from the motorcycle faster.


Thanks.
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Old 10-08-2009   #2
A4est
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Re: Vulcan 1500 backfire, popping, and cracking pipe problem...

It usually means it is running lean. You sure anything else hasn't changed? Like a new free flowing air filter? If not, check for leaky vacume lines and/or if air is getting into the boots between the carbs and the cylinders.
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Old 10-08-2009   #3
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Re: Vulcan 1500 backfire, popping, and cracking pipe problem...

A few weeks ago the fuel companies switched to the winter mix. (yes it is different) Try adding some fuel booster of running a higher octane.
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Old 10-09-2009   #4
KYRider
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Re: Vulcan 1500 backfire, popping, and cracking pipe problem...

Quote:
Originally Posted by A4est View Post
It usually means it is running lean. You sure anything else hasn't changed? Like a new free flowing air filter? If not, check for leaky vacume lines and/or if air is getting into the boots between the carbs and the cylinders.
I had a K&N air filter in the bike, took it out to see if it would make a difference where I put in the stock air filter, and it made no difference. I usually use the K&N air filter during the warmer months (which hasn't been that too much this year) and put in the stock air filter during the colder months.
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Old 10-09-2009   #5
KYRider
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Re: Vulcan 1500 backfire, popping, and cracking pipe problem...

Quote:
Originally Posted by Benny View Post
A few weeks ago the fuel companies switched to the winter mix. (yes it is different) Try adding some fuel booster of running a higher octane.
I started to use the plus gas rather than the regular gas to see if that would help, no difference. When fuel companies changed last year to the winter blend, I didn't have this problem. I also ran SeaFoam through the tank a few times and it didn't help the problem.
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Old 10-10-2009   #6
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Re: Vulcan 1500 backfire, popping, and cracking pipe problem...

If the bike is running well but just backfires etc... It sounds like an exhaust leak to me. I have seen this a few times... Bad exhaust gasket or broken weld and the thing pops and cracks like crazy but continues to run well. More noticeable pops while decelerating.
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Old 10-11-2009   #7
KYRider
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Re: Vulcan 1500 backfire, popping, and cracking pipe problem...

I believe I found the problem today. The Vance and Hines Classic II pipe connecting to the rear cylinders was a tad loose where if you pull on the pipes, you would hear it rattle. However I cannot find the part anywhere to buy a replacement part. The round metal gasket (unsure if the correct name at this time) connecting the pipe to the rear cyclinder is slighty bowed where it will not sit flat. It is not bent/bowed that much where it would be good to bend it back (if possible).
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Old 10-11-2009   #8
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Re: Vulcan 1500 backfire, popping, and cracking pipe problem...

Damn I'm good.....Did I mention that I'm bad ass and stuff... lmao

bend it back....if it breaks...weld it. You talking about Flange gasket? Pics are helpful.
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Old 10-12-2009   #9
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Re: Vulcan 1500 backfire, popping, and cracking pipe problem...

Hi-temp silicone might seal a really small leak.


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Old 10-12-2009   #10
KYRider
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Re: Vulcan 1500 backfire, popping, and cracking pipe problem...

After putting the pipes and gaskets back together, I took a small ride. The bike still backfires some with popping and cracking. I had hoped that would fix it, but it still occurs.
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