2007 Rsmv Backfiring

[curtisb]

Since This Is My First V Four Need To Ask Some Dumb Questions. Is It Common For The Venture To Have An Occasional Backfire. Always On The Right Cylinder Bank. Usually Only Until It Warms Up. Sometimes A Backfire When Cranking. Sometimes Slight Backfire On Decel At Low Speeds. 2500 Miles On Engine. Installed New Plugs Since Carb Float Has Stuck One Time. Thanks For Any Info.

[KeithR]

Have you had your carb's synchronized lately. Maybe causing it?

 

Keith

[mike_kelly_68]

Are you running aftermarket pipes or tips?? If the restriction of the intake and exhaust are not matched you will get some back fire. I am on a 2006 running Bub Slipons and experiance some backfiring when cold. Took it to have exhaust gases ran and they said that all were well within spec. not to worry about backfire.

[V7Goose]

There are numerous other threads with detailed discussions of this problem, but the three main causes of this problem are:

1. Vacuum leaks
   
2. Exhaust leak (almost always at the "Y" pipe joint)
   
3. carb synchronization
   

A lot of people here think you need to plug the Air Induction System to stop the problem, but that is not necessary. Since your bike is new, a good dealer should be able to find and fix the problem easily. If you don't have a good dealer, check out the other discussions here, post your questions, and we will help you through it.

Goose

[curtisb]

Bike Is Factory. No Add Ons Yet. Any Ideas On Most Logical Place For A Vacum Leak, And Would Plugging Ais Help, Also Does It Damagae Anything To Plug Or Affect Warranty.

Thanks For Info

[V7Goose]

Plugging the AIS just pollutes our air more. If the bike is popping on decel, something is wrong, so why not fix it instead of just trying to hide it?

 

OK, I'll get off my soap box now. Frankly, your symptoms sound more like carb sync to me. If you have a vacuum leak, it would be at one of the vacuum lines or nipple covers on the intake manifolds. The vacuum lines are very easy to tear near the ends of the nipples if they are put on or off with pliers. Spray each nipple with carb cleaner or WD40 while the bike is idling - any change in engine sound shows a vacuum leak.

 

If you have an exhaust leak, you should be able to feel it with your hand or see it blow away smoke from a cigarette held under the Y joint. You can also look for a gray sooty film from the exhaust gasses on the chrome heat shields around the Y joint.

Goose

[BradT]

I find when mine starts to pop it needs a good carb sync or shut the Choke off.

 

Also when I was in Colorado at higher elevations nothing helped it ackfired all day long.

 

Brad

[VTirelli]

I find when mine starts to pop it needs a good carb sync or shut the Choke off.

 

Also when I was in Colorado at higher elevations nothing helped it ackfired all day long.

 

Brad

 

LOL I had this problem too when we were riding the Smokey Mountains....I had to ride in the back bacause it was scaring everyone behind me

[V7Goose]

I find when mine starts to pop it needs a good carb sync or shut the Choke off.

 

Also when I was in Colorado at higher elevations nothing helped it ackfired all day long.

Brad

Higher elevations do exacerbate the problem, but the causes are the same. In this case, I'd bet a LOT on a vacuum leak. It doesn't have to be a major leak - even very fine cracking in the vacuum port caps will cause it. When I first ran into this problem on my 05, it started last year as I was leaving Fort Worth for the rally in Colorado. It was just occasional in Texas, but got a lot worse as we headed into the mountains (my brother and I criss-crossed the Rockies on the way there and hit 17 passes over 10,000 feet). The mountains cause the problem to be worse not just because of the altitude, but because you are running the bike under load and rolling the throttle off more, causing the unburned fuel to collect in the pipe a lot more than normal.

 

I learned a lot about the vacuum leak problem on this trip as I tried to diagnose the issue. I SWORE the minor age cracks in the vacuum port caps could NOT POSSIBLY be leaking, especially since the bike was only two years old. But various attempts to seal them all provided some improvement (but not complete resolution), indicating that they were indeed the cause. Finally, I got one new cap at the Yamaha shop in Fort Collins, and made another by slipping a new piece of gas line over the nipple and doubling it over, then slipping the spring clamp back on top. REPLACING BOTH the caps finally completely resolved the problem. Trust me, you don't have to live with the problem!

Goose

[Gene-b]

I'm in Colorado, 5280 ft above sea level.I've done the same thing now on 2 RSV's to stop the backfire. Plug the AIS system. Don't ask me how to do it, I had it done at my dealer. (He is a friend of mine). I have used stock pipes and now run BUB's. No backfire at all, even at very high elevations. I don't know if this will work at lower elevations, but when I travel to lower elevations I don't seem to have any problems.

 

Good Luck

 

Gene

[SaltyDawg]

Plugging the AIS doesn't hurt anything and it's a quick fix. More than likely your problem is the bike is running too rich and needs to be leaned out. I suggest colortuning it and then carb syncing for best results. I personally wouldn't have a dealer do this since it is NOT covered by warranty and they WILL hit you for a lot of money.

 

It's not hard to do if you are mechanically inclined, but the equipment needed will run you about $160.00 total. Or you could hook up with a fellow venture rider who already has the stuff at one of the many meet and eats. Takes about an hour to do from start to finish. Maybe a little longer if it's your first time.

[V7Goose]

Plugging the AIS doesn't hurt anything and it's a quick fix.

I agree, it doesn't hurt anything on the bike. But it DOES hurt our air and our health. If that was the only way to fix the problem, I might understand the choice, but it is not.

Goose

[curtisb]

Thanks For A Lot Of Info. Does Not Look Like A Leak At Y Pipe And Vacum Lines Look Good. Not A Lot Of Popping (backfire) Just A Little On Decel.

[SaltyDawg]

I agree, it doesn't hurt anything on the bike. But it DOES hurt our air and our health. If that was the only way to fix the problem, I might understand the choice, but it is not.

Goose

 

You know if we were running smoke belching 2 strokes I might worry about it, but one person smoking a pack of cigarettes probably puts more pollutants in the air than one of these scoots with a plugged AIS.

 

But I stated in my post what I thought the problem was and how to fix it.

 

BTW I don't buy into the Global Warming/Carbon Credit garbage going on. This world was here long before we came along and it will be here long after we have turned to dust.

[James Ardrey]

I'm in Colorado, 5280 ft above sea level.I've done the same thing now on 2 RSV's to stop the backfire. Plug the AIS system. Don't ask me how to do it, I had it done at my dealer. (He is a friend of mine). I have used stock pipes and now run BUB's. No backfire at all, even at very high elevations. I don't know if this will work at lower elevations, but when I travel to lower elevations I don't seem to have any problems.

 

Good Luck

 

Gene

Ditto. If mine was a vacuum leak it would have continued after plugging the AIS. The AIS system builds up excess fuel causing the backfiring the same way a vacuum leak or too much back pressure in the exhaust does. Mine no longer backfires at any elevation, exceleration, deceleration or any other time since I plugged the AIS. Git er done.

[MAINEAC]

I agree, it doesn't hurt anything on the bike. But it DOES hurt our air and our health. If that was the only way to fix the problem, I might understand the choice, but it is not.

Goose

 

Goose I think you have the wrong idea on this AIS thing... The way I understand it is the AIS just adds air to the exhaust gas to dilute it to get by the emmissions testing... like adding water to a shot of Whiskey... You're still drinking a shot just diluted with water.. The same amount of polutants is coming out of the tailpipes whether the AIS is hooked up or plugged.. The AIS just dilutes it for emmisions testing... Plugging the AIS does not add polutants to the enviroment.

[gibvel]

Goose I think you have the wrong idea on this AIS thing... The way I understand it is the AIS just adds air to the exhaust gas to dilute it to get by the emmissions testing... like adding water to a shot of Whiskey... You're still drinking a shot just diluted with water.. The same amount of polutants is coming out of the tailpipes whether the AIS is hooked up or plugged.. The AIS just dilutes it for emmisions testing... Plugging the AIS does not add polutants to the enviroment.

 

The way I've always understood the system and AIS in general is that the fresh air is introduced into the exhaust port and that fresh air causes what's left of the unburned hydro-carbons to finish burning, there by reducing the amount of unburned HC in the exhaust. So, by this definition, if correct, means that there would, in fact, be less HC exiting the exhaust meaning less pollution not just diluted pollution.

[MAINEAC]

gibvel sounds like you're talking about a catylytic converter... I don't think there's any burning in our pipes going on... EXCEPT the guys with the backfiring issues..

[gibvel]

gibvel sounds like you're talking about a catylytic converter... I don't think there's any burning in our pipes going on... EXCEPT the guys with the backfiring issues..

 

No, because the stuff that I read about it says that some systems inject fresh air into the catalytic converter, as well, to further burn the HC. Like I said I may be off but that's what I read on the subject.

[Guest Dandy1]

I run BUB slip ons on my 06, bike backfired everytime I shifted into 2nd and 3rd gear. Plugged AIS and backfire is gone.

[gibvel]

I don't get a backfire eg. no loud popping. I do, however get a "gurgling" or a "burbling" (don't know if that's all that much help ) on deceleration that I'd like to get rid of. I plugged the AIS once and found that didn't help or, if it did, it wasn't much change.

[SaltyDawg]

I don't get a backfire eg. no loud popping. I do, however get a "gurgling" or a "burbling" on deceleration that I'd like to get rid of.

 

Is that you or your scoot?

[gibvel]

Is that you or your scoot?

Hardy, har, har!! Guess I gotta watch what I type around you guys. Should have learned that by now.

[V7Goose]

Ditto. If mine was a vacuum leak it would have continued after plugging the AIS. The AIS system builds up excess fuel causing the backfiring the same way a vacuum leak or too much back pressure in the exhaust does. Mine no longer backfires at any elevation, exceleration, deceleration or any other time since I plugged the AIS. Git er done.

This is not a correct explanation of how the AIS works or the purpose. Inducting air into the exhaust system is to cause the unburned hydrocarbons (gas) to burn before they are blown out of the tail pipe. Just for further explanation, the only difference between a car's air injection system and our air induction system is a smog pump. Our system is passive, with the air just being sucked into the header pipe from the exhaust gasses rushing buy the induction ports.

1. Hydrocarbons: this class is made up of unburned or partially burned fuel, and is a major contributor to urban smog, as well as being toxic. They can cause liver damage and even cancer.
   
2. The AIS reduces the products of incomplete combustion (hydrocarbons and carbon monoxide) by inducting fresh air into the exhaust manifolds of the engine. In the presence of this oxygen-laden air, further combustion occurs in the manifold and exhaust pipe.
   

The popping we hear is an afterfire, not a backfire (backfire is an explosion through the intake tract or carburetor). The purpose of the AIS valve is to STOP the afterfire caused by the oxygen inducted into the exhaust manifold when the accumulation of unburned gas is too great. When the intake vacuum suddenly increases from snapping the throttle shut, that causes the valve to close, stopping the air from being inducted into the exhaust system, and STOPPING an afterfire at that time.

 

So now the question is why the unburned gas in the exhaust is sometimes so high that we get an afterfire while the AIS valve is in the normally open position? This is caused by incomplete combustion of all the gas sucked into the cylinder. The incomplete combustion can be from multiple causes, including too lean condition (caused by that intake vacuum leak I keep yelling about), fouled plugs, unbalanced carburetors, or faulty ignition system. ALL of those things are bad, and that is why I keep saying that it is more important to fix the real cause of the afterfire than to just hide it by stopping the air induction.

 

I hope that explanation helps.

Goose

[gibvel]

This is not a correct explanation of how the AIS works or the purpose. Inducting air into the exhaust system is to cause the unburned hydrocarbons (gas) to burn before they are blown out of the tail pipe. Just for further explanation, the only difference between a car's air injection system and our air induction system is a smog pump. Our system is passive, with the air just being sucked into the header pipe from the exhaust gasses rushing buy the induction ports.

1. Hydrocarbons: this class is made up of unburned or partially burned fuel, and is a major contributor to urban smog, as well as being toxic. They can cause liver damage and even cancer.
   
2. The AIS reduces the products of incomplete combustion (hydrocarbons and carbon monoxide) by inducting fresh air into the exhaust manifolds of the engine. In the presence of this oxygen-laden air, further combustion occurs in the manifold and exhaust pipe.
   

The popping we hear is an afterfire, not a backfire (backfire is an explosion through the intake tract or carburetor). The purpose of the AIS valve is to STOP the afterfire caused by the oxygen inducted into the exhaust manifold when the accumulation of unburned gas is too great. When the intake vacuum suddenly increases from snapping the throttle shut, that causes the valve to close, stopping the air from being inducted into the exhaust system, and STOPPING an afterfire at that time.

 

So now the question is why the unburned gas in the exhaust is sometimes so high that we get an afterfire while the AIS valve is in the normally open position? This is caused by incomplete combustion of all the gas sucked into the cylinder. The incomplete combustion can be from multiple causes, including too lean condition (caused by that intake vacuum leak I keep yelling about), fouled plugs, unbalanced carburetors, or faulty ignition system. ALL of those things are bad, and that is why I keep saying that it is more important to fix the real cause of the afterfire than to just hide it by stopping the air induction.

 

I hope that explanation helps.

Goose

Very nice explanation Goose. Understand that a whale of a lot better now. So my next question is this:

 

The gurgle on decel that I'm getting doesn't sound like it fits into the "afterfire" category given this explanation. Is that a correct assumption or is it still a type of afterfire.