Deceleration popping

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11/2/2017 2:13 PM

Have an 09 kx 450 with full pc ti5 pipe. Run 110 oct cam2 gas in it. HC wiseco piston.

Having some popping issues on deceleration. Checked my valves as my initial thought was tight exhaust valves. All that is in check.

Only other thing i can think of is the bike is injecting too much gas and some of its getting into the pipe and causing the pop.

Not sure of anythIng else i could be overlooking. I dont hear this from other bikes at the track. Is this normal or due to a somewhat hopped up motor?

The pops arent loud gunshot like backfires. Just small pops.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

11/2/2017 3:09 PM

I had that probably turned out it was a little to rich but could be different for your case ,did you have it remapped

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11/2/2017 3:11 PM

No. I bought the bike used. As far as i know the pipe was done with no remap.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

11/2/2017 3:25 PM
Edited Date/Time: 11/2/2017 3:27 PM

You shouldn't be running cam 2 in that bike ,it's design for old muscle cars it's really high in lead good for 2-stroke and old cars with steel heads and steel valves. all modern gas for four strokes are LEAD free for a reason. I didn't even think you can still buy cam 2

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11/2/2017 3:31 PM

Probably too lean

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11/2/2017 3:34 PM

colintrax wrote:

Probably too lean

Yep, decel popping through the exhaust is most likely lean.

Leaded fuel is perfectly fine for modern four strokes, just not needed in your application.

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Tomac and/or Anderson for 2020.....

11/2/2017 5:56 PM

colintrax wrote:

Probably too lean

BobPA wrote:

Yep, decel popping through the exhaust is most likely lean.

Leaded fuel is perfectly fine for modern four strokes, just not needed in your application.

So with the pc pipe its running too much air. Makes sense. I buy the race gas because the bike wont start on 97.

Sounds like i need a remap or deal with it.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

11/2/2017 5:58 PM

colintrax wrote:

Probably too lean

BobPA wrote:

Yep, decel popping through the exhaust is most likely lean.

Leaded fuel is perfectly fine for modern four strokes, just not needed in your application.

Acidreamer wrote:

So with the pc pipe its running too much air. Makes sense. I buy the race gas because the bike wont start on 97.

Sounds like i need a remap or deal with it.

I wouldn't just deal with it, get a remap. It'll reduce the popping, make the bike more quick, and might help you get more life outta topends.

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11/2/2017 8:17 PM

Exhaust leak ?

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11/2/2017 8:59 PM

Did it randomly start popping? Seen many header leaks on those bikes. Since you already do top ends every 10 hours, a small investment for a tuner is well worth it.

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11/2/2017 9:56 PM

If the pipe was pulled or replaced and a new exhaust gasket was not installed it will cause a lean condition in the pipe and cause your issue. Try replacing that gasket and see if that cures the issue before doing anything else.

Paw Paw

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11/3/2017 6:04 AM

imoto34 wrote:

Did it randomly start popping? Seen many header leaks on those bikes. Since you already do top ends every 10 hours, a small investment for a tuner is well worth it.

Its always popped but ive never thought anything of it since everything is in spec and tuned right mechanically.

Someone pointed it out to me and since then ive noticed not every bike does it.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

11/3/2017 11:20 AM

Again, I will bet that when the new pipe was installed the old exhaust gasket was reused and thus is leaking and causing a lean condition in the exhaust that is causing the popping. I see this a lot. Folks will spend hundreads of dollars on a new pipe and then scrip and reuse a $4 gasket.

Paw Paw

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11/3/2017 11:57 AM

http://www.mikuni.com/tg_backfires_in_exhaust.html

Pretty much all the info you need is located here.

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Race Bike: 2018 KTM 350SXF

Other Bikes: 1985 CR80R, 1990 CR250R, 1998 PW80, Specialized Fuse Comp 29.

Sold: 2016 YZ250F, 2012 CRF250R

11/3/2017 12:09 PM

Paw Paw wrote:

Again, I will bet that when the new pipe was installed the old exhaust gasket was reused and thus is leaking and causing a lean condition in the exhaust that is causing the popping. I see this a lot. Folks will spend hundreads of dollars on a new pipe and then scrip and reuse a $4 gasket.

Paw Paw

Paw Paw,
I noticed you're in Benton. Do you ride local tracks? I live in Shreveport.

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11/3/2017 12:30 PM
Edited Date/Time: 11/3/2017 12:34 PM

Paw Paw wrote:

Again, I will bet that when the new pipe was installed the old exhaust gasket was reused and thus is leaking and causing a lean condition in the exhaust that is causing the popping. I see this a lot. Folks will spend hundreads of dollars on a new pipe and then scrip and reuse a $4 gasket.

Paw Paw

Giygas wrote:

Paw Paw,
I noticed you're in Benton. Do you ride local tracks? I live in Shreveport.

I have a membership at SWAN in Tyler and that is my main riding track. I have been going there for about 34 years now. I did ride regularly at Desoto in the past. I also ride at Red Bug on occasion. I have ridden at Dirt Slingers from time to time. My riding days are limited due to health issues. I normally ride with some riders of my own age group ( over 70) and we have just as much fun riding together as the kids do. I normally do the Diamond Don's even each year and the Desoto Vet race in October, but not this year. My riding buddies and I do make riding trips on weekdays to Rio Bravo and Three Palms from time to time. From time to time I go to South Louisiana and ride Hwy 70, Down South and Gravity Alley.

Paw Paw

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11/4/2017 3:38 AM

Is lean, good opinion here already smile

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11/4/2017 6:26 AM

Paw Paw wrote:

Again, I will bet that when the new pipe was installed the old exhaust gasket was reused and thus is leaking and causing a lean condition in the exhaust that is causing the popping. I see this a lot. Folks will spend hundreads of dollars on a new pipe and then scrip and reuse a $4 gasket.

Paw Paw

Im waiting on that gasket this morning. Gotta love RM’s overnight shipping. Ill let you guys know what happens at the track today.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

11/4/2017 9:06 AM

You can also adjust throttle position sensor to get into the next fuel cell to richen it up a bit.

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11/6/2017 12:33 AM

Try this it worked for one of the factory teams i was at a test day with 2 months ago. The team couldn’t get the pop to go even with remapping so they used the washer and it stopped.
Put an washer under the spark plug to increase the distance from electrode to top of the piston.
It’s quick and cheap.

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11/6/2017 4:32 AM

I replaced that crush washer for the header. The old one was damn near melted away lol! Didnt fix the problem so ill try to remap.

If more people give credibility to moving the spark plug ill try it. Speaking of which i didnt try a new plug yet.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

11/6/2017 5:09 AM

Have you ever Repacked the Silencer?

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11/6/2017 5:49 AM

Acidreamer wrote:

I replaced that crush washer for the header. The old one was damn near melted away lol! Didnt fix the problem so ill try to remap.

If more people give credibility to moving the spark plug ill try it. Speaking of which i didnt try a new plug yet.

That sure indicates it was leaking. It also tells me you are running real lean when you chop the throttle. You may be able to correct that with a TPS reset. It may also have a partially clogged injector that needs to be cleaned.

Paw Paw

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11/6/2017 5:58 AM

526 wrote:

Have you ever Repacked the Silencer?

No

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

11/6/2017 2:04 PM

Acidreamer wrote:

I replaced that crush washer for the header. The old one was damn near melted away lol! Didnt fix the problem so ill try to remap.

If more people give credibility to moving the spark plug ill try it. Speaking of which i didnt try a new plug yet.

Paw Paw wrote:

That sure indicates it was leaking. It also tells me you are running real lean when you chop the throttle. You may be able to correct that with a TPS reset. It may also have a partially clogged injector that needs to be cleaned.

Paw Paw

Im going to give all of that a try. I noticed my high idle and normal idle isnt a whole lot different. I think i twisted the knob and messed it up. Might be a cause too.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

11/7/2017 11:44 AM

I had a 09 when they came out. Had a recall on the throttle body. They were cracking. Mine never did but i got it fixed anyways. My 13 kx450 popped i bought it used and the tps was slightly off.

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