Newbie Exhaust Question

[bryco13]

Hoping not to make myself seem too dumb, here goes. I have recently put a new exhaust on my bike, I installed it myself, cause I like to learn how things work. I have noticed in addition to it being way loud (which is ok, I wanted louder than stock), I have noticed it backfires when downshifting or just letting off the throttle. I don't beat on the bike, not running at high revs and downshifting fast, just riding normally. I asked the local shop I go to, and they said it was installed very well and suggested a Power Commander, to remap and stop the backfiring. Will this really help, or is there a way to stop the motor from backfiring without spending an additional $300+ . If it matters the bike is a 2007 ninja 650r, which is the parallel twin, and the exhaust is a Jardine GP-1 slip on exhaust. Thanks ahead for any help - bryan

p.s. The box the jardine came in said "GP-1, race core", this isn't the problem is
it? I thought that just meant it was basically a straight pipe.

[nilez]

not sure if your bike has them, but look into smog block off plates. Also, the power commander will help after you remap the fuel injection. Even still, there may be some flame spitting with the new pipe, as the baffles in it are straight through and larger than stock = flames travel quicker to get to the end of the pipe.

BOTTOM LINE: don't fuggin worry about it, we buy aftermarket pipes for sound, performance, and badassness

[butcher bergs]

It's backfiring because it's essentially running lean now.
A PCIII is your friend.

I can do the install but you'll have to download the map yourself.

There should be generic maps on the PCIII website

[Thunderbisciut]

Decel "popping" is usually a lean condition.

I say if you're going to do any other engine mods, then do them now and get the PC


Edit: damn tv distracts me and two peoples get in before me

[Dieseldan]

had the same problem with my 675, gotta tune it bro

[SilverGhost]

Hoping not to make myself seem too dumb, here goes. I have recently put a new exhaust on my bike, I installed it myself, cause I like to learn how things work. I have noticed in addition to it being way loud (which is ok, I wanted louder than stock), I have noticed it backfires when downshifting or just letting off the throttle. I don't beat on the bike, not running at high revs and downshifting fast, just riding normally. I asked the local shop I go to, and they said it was installed very well and suggested a Power Commander, to remap and stop the backfiring. Will this really help, or is there a way to stop the motor from backfiring without spending an additional $300+ . If it matters the bike is a 2007 ninja 650r, which is the parallel twin, and the exhaust is a Jardine GP-1 slip on exhaust. Thanks ahead for any help - bryan

p.s. The box the jardine came in said "GP-1, race core", this isn't the problem is
it? I thought that just meant it was basically a straight pipe.

This condition is due to the emissions system on the bike that is set for factory back pressure. This the most common problem with exhaust swap.
What happens is when you let off the throttle it injects air into the system to lean it out the hydrocarbons so it meets the epa standards.
On my SV I had to by a kit that consisted of two block off plates and a resister so my efi light would not come on.
You don't need a PC3, you just need to block of the air going up to your airbox.
I forgot to mention this is called the pair valve.

[The Snowman]

Decel popping can also be from exhaust leaks.

[ICCE]

Yes, most of this is almost right.
What is REALLY happening is a hydraulics flow principle.
With the change in the back pressure, the popping is actually unburnt fuel that travels through the cylinder while the intake and exhaust valves are open for a small degree of travel. With the lessened back pressure, you get the popping from the hot exhaust gas igniting the unburnt fuel in the header and the resulting "pop" comes out. A power commander changes the fuel/air mixture to compensate. With more fuel, the mixture becomes heavier and requires more velocity to carry it from the jet(read injector or carb jet) to the cylinder. The lack of back pressure already does this. With this in mind, there are three schools of thought on what to do.
1. Power Commander.
2. Old Harley baffle trick...involves a bolt, lock nut and a flat washer...simple and works amazing...drag racers used to use this.
3. Wrap the new inserts (if I read that right) with more muffler packing.

First, make sure that you're not sucking air in through the exhaust joints.
Hold a lit stick of incense next to and around each possible exhaust joint. You'll see the smoke flow right into the air leak. Race the throttle a bit at each joint to get the popping.

pm me if you want more details on the Harley trick.

[Doc]

I'll go with it is running lean. You need more fuel to mix in there to get the most benefit from the new exhaust. PCIII is the ticket.

If you block off the air it will work too but I bet that brings up a host of other problems (Your restricting the engine at this point)

[Doc]

Yes, most of this is almost right.
What is REALLY happening is a hydraulics flow principle.
With the change in the back pressure, the popping is actually unburnt fuel that travels through the cylinder while the intake and exhaust valves are open for a small degree of travel. With the lessened back pressure, you get the popping from the hot exhaust gas igniting the unburnt fuel in the header and the resulting "pop" comes out. A power commander changes the fuel/air mixture to compensate. With more fuel, the mixture becomes heavier and requires more velocity to carry it from the jet(read injector or carb jet) to the cylinder. The lack of back pressure already does this. With this in mind, there are three schools of thought on what to do.
1. Power Commander.
2. Old Harley baffle trick...involves a bolt, lock nut and a flat washer...simple and works amazing...drag racers used to use this.
3. Wrap the new inserts (if I read that right) with more muffler packing.

First, make sure that you're not sucking air in through the exhaust joints.
Hold a lit stick of incense next to and around each possible exhaust joint. You'll see the smoke flow right into the air leak. Race the throttle a bit at each joint to get the popping.

pm me if you want more details on the Harley trick.

WELCOME JOHN!!!

[*GhostRide37]

mmm i love popping

[bryco13]

thanks for all the responses, don't get me wrong, i love the backfire noises, but i guess what i am really wondering, but didn't quite ask, is will this hurt my engine? will i have a problem in 2k miles cause i was an asshole with a loud exhaust that likes to backfire?

[butcher bergs]

Not saying it's certainly going to happen but a lean condition has been known to burn up valves.

[SilverGhost]

thanks for all the responses, don't get me wrong, i love the backfire noises, but i guess what i am really wondering, but didn't quite ask, is will this hurt my engine? will i have a problem in 2k miles cause i was an asshole with a loud exhaust that likes to backfire?

At a minimum you will prematurely blow out your packing in your can.
No its not good for your motor.

[BostonSVkid]

eBay Motors: DYNOJET POWER COMMANDER PC USB 06-08 KAWASAKI NINJA 650 (item 130221911425 end time Sep-08-08 16:59:52 PDT)

Thats a good price. Just pick it up and be done with it. Best part is if you ever need to change something you just hook up your PC and change the tune.

I just got my PCIII hooked up and my bike runs like a F'ing raped ape now.

[Cmorsch]

Hoping not to make myself seem too dumb, here goes. I have recently put a new exhaust on my bike, I installed it myself, cause I like to learn how things work. I have noticed in addition to it being way loud (which is ok, I wanted louder than stock), I have noticed it backfires when downshifting or just letting off the throttle. I don't beat on the bike, not running at high revs and downshifting fast, just riding normally. I asked the local shop I go to, and they said it was installed very well and suggested a Power Commander, to remap and stop the backfiring. Will this really help, or is there a way to stop the motor from backfiring without spending an additional $300+ . If it matters the bike is a 2007 ninja 650r, which is the parallel twin, and the exhaust is a Jardine GP-1 slip on exhaust. Thanks ahead for any help - bryan

p.s. The box the jardine came in said "GP-1, race core", this isn't the problem is
it? I thought that just meant it was basically a straight pipe.

There are a couples different ways to you try to fix this on your bike.

The first is to get a PCIII which you should do anyways since our bikes run lean to begin with. The second some people say works is plugging your pair valves. And the third is doing both.

Gary at Blue Ridge Performance would be able to tell you exactly what you will need to do, as he races the 650r. And also stocks lots of performance and aftermarket parts for it.

P.S. Watch the rivots on the can, the older models tended to blow apart after a few thousand miles.

[bryco13]

Cmorsch, I've dealt with BRP for most of my other store bought mods. Looks like I'll be going with a pcIII and new air filter as my winter project, thanks for all the advice folks !