[Fatboy315]

So I have an 2005 that pops and backfires in the low to mid range, but pulls hard af after that. It’s like when you let the clutch out it stutters a little bit, coughs and pops then takes off. It’s got brand new plugs in it. And it’s perfect In neutral, or if you pull in the clutch when it starts to stutter. It’s only under load. Other then a yoshi slip on the bikes stock. I tried using seafoam and it just killed the plugs, which is why it’s now got a bn set in it.

 

[michael4012]

Sounds like tune to me, not knowing the history with you and that bike. But typical tune issues from things like, removing secondary flies, fitting a full system racing filter cam dialing etc, and also throttle bodies out of sinc. Popping and backfiring isnt a fuel starvation issue normally.

 

[SkyDork]

What michael said.

It's not electrical related to the plugs. It's a fueling problem. And it's afterfiring, not backfiring. Backfiring goes backwards up through the intakes. Afterfiring is what occurs AFTER the combustion process happens and too much unburnt fuel gets into the exhaust pipe. You're running too rich for some reason.

 

[Fatboy315]

What michael said.

It's not electrical related to the plugs. It's a fueling problem. And it's afterfiring, not backfiring. Backfiring goes backwards up through the intakes. Afterfiring is what occurs AFTER the combustion process happens and too much unburnt fuel gets into the exhaust pipe. You're running too rich for some reason.

That’s what I figured. Now my next question is should I send out my stock ecu to have it reflashed? Or buy a PCV?

 

[Fatboy315]

Sounds like tune to me, not knowing the history with you and that bike. But typical tune issues from things like, removing secondary flies, fitting a full system racing filter cam dialing etc, and also throttle bodies out of sinc. Popping and backfiring isnt a fuel starvation issue normally.

So as far as I’m aware the only thing that’s been done is a yoshimura slip on. There’s no power commander or anything like that. So my next question would be what would you suggest to remedy the situation? Should I get a PCV and download a new tune, or send out the stock ECU to be flashed? I’m not aware of any dyno tuners in my area that will actually tune sport bikes, they’re all Harley shops 🙄🙄

 

[SkyDork]

So as far as I’m aware the only thing that’s been done is a yoshimura slip on. There’s no power commander or anything like that. So my next question would be what would you suggest to remedy the situation? Should I get a PCV and download a new tune, or send out the stock ECU to be flashed? I’m not aware of any dyno tuners in my area that will actually tune sport bikes, they’re all Harley shops 🙄🙄

Well, that's your problem. To get it done correctly, it should be tuned on a dyno to see what you're getting from the changes and how it's responding to that. Downloading anything related to the PCV or sending it off to be flashed will be a crap-shoot. If someone can't measure what your bike is doing, then they can't really change it to account for things.

Based on the age of that bike, a PCV might be a bit easier to make tweaks to it yourself than a flash would. The G1 didn't benefit from a reflash like the newer ones do. So unless you plan to buy the kit to reflash it yourself, install it all and start reworking the fueling maps yourself, then the PCV would be better and easier. Sending the ECU off to someone else is no guarantee and then you're stuck with that. If you don't really know what you're doing with all that, then open up your wallet a bit wider and get an autotune set up with the PCV or the Woolich reflash software.

 

[michael4012]

I don't know your skill or tooling level but, I'm not sure a slip on would cause so much disruption but possibly it was slightly leaner before the slip on was fitted and that slightly lower back pressure reduced scavenging to the point of disruptive lean. But for me I would do the basics replace or clean air filter if its performance, and then synchronise the throttle bodies, although that alone doesn't explain the in out gear difference but may help make it more manageable if getting a dyno fuel and flash isn't practical. Also if it is an aftermarket performance filter then maybe switching back to a paper OE filter may richen enough to make it more manageable But in truth I think a full flash and map will cure it.

 

[Fatboy315]

I don't know your skill or tooling level but, I'm not sure a slip on would cause so much disruption but possibly it was slightly leaner before the slip on was fitted and that slightly lower back pressure reduced scavenging to the point of disruptive lean. But for me I would do the basics replace or clean air filter if its performance, and then synchronise the throttle bodies, although that alone doesn't explain the in out gear difference but may help make it more manageable if getting a dyno fuel and flash isn't practical. Also if it is an aftermarket performance filter then maybe switching back to a paper OE filter may richen enough to make it more manageable But in truth I think a full flash and map will cure it.

Awesome I appreciate it. I just got a new K&N in yesterday for it and I ordered the PCV last night. The only thing I haven’t done is sync the throttle bodies, so if the new filter and map doesn’t work it’s next LOL.

 

[Energydrinkvape]

My new bike has a similar issue...in 4th gear at around 7k rpm there was a bunch of pops and seeming fuel cut, but it would go away at lower or higher revs. Not sure what's been done on it yet 🤓 but the guy at the shop thought he heard an issue with the pair valve. Bike has a full Graves exhaust

 

[SkyDork]

My new bike has a similar issue...in 4th gear at around 7k rpm there was a bunch of pops and seeming fuel cut, but it would go away at lower or higher revs. Not sure what's been done on it yet 🤓 but the guy at the shop thought he heard an issue with the pair valve. Bike has a full Graves exhaust

Kawasaki's don't have a PAIR valve. That's a Suzuki thing. That would create some popping in the exhaust, but has nothing to do with a "fuel cut".

It's a KLEEN valve (Kawasaki Low Emission Exhaust Nsomething) on your Kawi. I puts fresh air into the exhaust to help burn up any raw fuel in there to make the catalytic converter more efficient. Raw fuel and air makes a fire if it gets not, and you hear that pop out the back. It has nothing to do with the fuel. Bypassing that is quick and easy to help eliminate that for exhaust changes.