Sputter sound from exhaust

[wvfirefighter-emt]

I have noticed a sputtering sound when I go up a steep grade around 5 -10 mph. Not sure if it is coming from the exhaust or the drivetrain. Anyone else hear this??

[jcummins]

I use my Teryx daily on a small ranch I have, and today it was used a lot, from first sun to dark. Very early I had one person riding with me, a fair amount, then this evening another person riding for a totally separate reason. Neither person was with me at the same time. They BOTH asked about the miss in the Teryx.....I do has a miss...but that's not what they was talking about. It was this sputter.

Kind of embarrasing to have people get in it and talk about the 'miss'. And, it actually seems it getting a bit worse. Kind of surprised with all the knowledge on this forum someone hasn't identified what this could be.

From those that posted, I belive only one person does NOT have the sputter. Anybody else? I want to fix this.

[Teee-rible]

Well, I know this is an old thread...something weird has happened and I thought I would relay it. I have done my oil bypass (from the air filter) and the sputtering has gone away...is it temporary...I don't know just rode for a couple hours??? The oil bypass is now completely out of the air box, and I plugged up the nipple on the air box. This may be a solution of that sputtering sound? Might explain why some people don't have that sputtering? Just thought I'd pass that along.

[Magellan]

I am 99% convinced that the sputtering is due to tuning issues and possibly the factory coils. I say this because I installed the Dynatek Coil Upgrade Kit and it was WAY lean in the midrange. Once I raised the needles by going to clip position 4 and got the midrange back where it needed to be with the Air Fuel Ratio Gauge, the sputter is 99% gone. I think it is a sputter between the idle mixture screw and the needle. I am working on a video of tuning using the NGK and the WEGO II A/F gauges. The WEGO is so much easier because you can graph out the test runs. Well worth the extra 100.00. I got the WEGO from Muzzy's and the NGK from Hunterworks.

[jcummins]

Originally Posted by Magellan

I am 99% convinced that the sputtering is due to tuning issues and possibly the factory coils. I say this because I installed the Dynatek Coil Upgrade Kit and it was WAY lean in the midrange. Once I raised the needles by going to clip position 4 and got the midrange back where it needed to be with the Air Fuel Ratio Gauge, the sputter is 99% gone. I think it is a sputter between the idle mixture screw and the needle. I am working on a video of tuning using the NGK and the WEGO II A/F gauges. The WEGO is so much easier because you can graph out the test runs. Well worth the extra 100.00. I got the WEGO from Muzzy's and the NGK from Hunterworks.

You may be right...but lean? I do agree this problem is the transition from mixture screw to the needle.

I thought, mine is rich, so I turned my fuel mixture screw in 1/8 turn., which leaned it up...and it helped with that flat spot, and the sputter. Still I wish it was better. I was wanting to lower my needle but already in the highest slot. Is your's lean because of the other mods? How would the coil make it that lean? This has me confused, but that's probably why it's not be figured out. At speed....I notice no miss or sputter.

[Magellan]

It is a WEGO III not a 2. Yes lots lean in the midrange. Coolest thing about the WEGO is the ability to graph the test rides. I thought I had my mixture dialed in with the NGK Air/Fuel Ratio Meter, thought...

The coil kit is reported to give hotter spark at low and midrange, not sure if this could make it lean or not. Maybe lean before, but I am assuming that with the hotter spark, more fuel is ignitable and needed to keep the mixture correct. With the WEGO III it is easy to get the mixture right and what I did was ride the same ride in all tests as closely as I could to help get easy to interpret results. Here are the NGK and WEGO III units velcro'd on my cup holder. The WEGO I have is modded to use the Lighter plug next to the cup holder and you can see the NGK from Hunterworks has aligator clips on it that I clip on the WEGO harness. Not pretty but works great and easy. These graphs show how I am getting much closer. I am now going to put hte WEGO on the rear cylinder and see what it needs, then hopefully take the carbs off ONE MORE TIME and that is it. Oh Joy.


OK here we go. Graph one is how I had it jetted with the NGK Meter and this is after installing the Dynatek Coil Kit. As you can see, the mid is lean. The REALLY big lean spike is going down my very steep driveway and feeder road, then right after that full throttle in L back up the driveway. All the charts will have the lean spike when going down the driveway and all come right back up the driveway after going down. The rest is a mix of idle, and on and off the throttle putting around the yard. The bottom of this post has a better explanation of the test ride so you can see what you are looking at better in the top 3 graphs. Higher numbers mean more lean, lower is rich.

Graph one - how it read after installing the WEGO III


OK now after moving the e-clips to position 2 from position 1 on the main needles. Giving more midrange fuel. Not much difference, but a little bit. I also opened up 1/2 turn on the idle mixture for this graph.


Ok now I opened up another 1/4 turn on the idle mixture as well as going to position 4 on the main needle. BIG improvement.

Again the BIG lean spike is going down the driveway and feeder road. Then back up.

The graphs are a HUGE help in dialing in the mixture and well worth the extra 120 the WEGO III costs over the NGK In my humble opinion, at least it was a lot easier for me.

Here is the last graph with marking on it to show. Red Arrow pointing down is when I go down my driveway in low with very little gas pedal, just enough to keep the clutch engaged, which is easier now and at even lower than stock RPM with the Dalton Clutch Kit BTW. The Blue Up arrow is WOT back up the hill. The parts labeled MID are me putt putting around the yard in Low moving about 5 to 25 or so MPH but easy on the gas maybe no throttle to about 1/.2 or so throttle. So looks like I need to go up in main jet size one step and the rest of this cylinder is done. Next cylinder please...

[travdude]

Excellent write up. Thanks.