HELP! Outlaw studders with heavy throttle

[Brandoh]

I'm working on an 07 Outlaw 500 IRS It has "Pure Polaris" E2 dual exhaust (i think it has been rejetted? the exhaust has been on there a long time, it was like that when the atv was bought used)

When it gets close to mid gear it starts to stumble/cut out/surge. It will start, idle, rev, and putt around with no problems.

I have already:

taken carb off and apart and cleaned everything I could get to, it didn't seem too dirty, but I got some stuff out.

Installed new NGK plug (gapped correctly) when I went to take out old plug, had to take the valve cover off because of crappy craftsmanship, there was a burr in the hole and the spark plug socket couldn't fit inside. When I finally got to the old plug, it was barely hand tight, it couldn't have had much of a seal, there was a bit of oil on the porcelain. I thought that was the problem, but no...

Air filter has been cleaned and re-oiled (K&N)

Changed fuel filter (if you can call what I took off a filter)

I took all of the plastics off, everything looks ok, no connections look off.

So what am I missing?

The fuel pump is a diaphragm type, so if it works, it works right?

Is there any way to check the ignition coil?

I am trying to fix this for a friend so I can have someone to ride with, any help would be greatly appreciated! Thanks!

[SMP63]

Try running a couple tanks of gas with SEA FOAM @ a mix of 3 oz. per gallon.
See if that helps. Then drop back to 1 oz. per gallon. Great stuff!!!!!!

[blueline15]

Any drastic change in elevation or air temp? Sounds like a jet problem.

[joshr08]

^^ my guess would be rich but just a guess. and for god sake get rid of that K&N while the motor still kinda runs they are junk and most likely part of the problem.

[Brandoh]

@SMP63: I have ran some lucas fuel treatment through it, no change. I do like Seafoam, it's good stuff. I will add that to the to do list.

@Blueline15: I really don't think so. My friend just bought this atv about a month ago from a guy he works with, who had just bought it from someone else who needed some quick cash. So history on this bike is minimal. I noticed a slight studder the first ride when I opened it up, but figured it just needed some carb cleaner. It seems like the problem has escalated, or now we are more comfortable with giving it more throttle. Originally I had thought it could have been the jets, (not that I know anything about carb jetting) but the exhaust is old and assuming the bike lived in Oklahoma the whole time I ruled it out. However, stupid me, didn't even look at the numbers on the jets when I took them out and cleaned the carb. So now I will open it up and look this time since you guys agree it could be a possibility.

@joshr08: Well it does smell like its running rich, but not smoking. The plug was dry but had soot/carbon on it similar to this pic Again, the plug was like finger tight, I cant believe that didn't make any difference. K&N filters are bad on the outlaws? I figured if they are oiled correctly and kept clean it would be a great air cleaner There is no prefilter on it though, that bothers me...

The elevation around here appears to be 1000-1500 feet, and with E2 Pure Polaris pipes (similar to these but with more wear) what jets should it be running?

[Brandoh]

Ok, I took the carb off again. I looked at the current jets Pilot: 32.5 Main 155
It says stock main is 150 and stock Pilot is 45

But It still has the pilot screw plug on it, does this mean it's never been re jetted?
I'm thinking the carb is running rich because of the plug color, dry black soot. So maybe I should just screw the pilot in 1/4 turn to lean it out a bit?

[Brandoh]

Played with the pilot screw tonight, made 3 separate adjustments and it still smells like its running rich, I've made no progress with plenty of wasted time...
Looks like I'm throwing in the towel.

[joshr08]

check your float height if its to high it will let fuel pretty much just run past your jet settings

[Brandoh]

*UPDATE*

I took the ATV to the shop, They have had it for about a month now.
The tech put a new jet kit on it, but it didn't fix it.
He said he found a lot of "junk" in the muffler and cleaned it out, That didn't fix it.
Now he is going to check the valves...

I don't know how to feel about it really. Is the tech just as uneducated as I am? Or is this really a strange problem? I guess we shall see...

[Brandoh]

Originally Posted by joshr08

check your float height if its to high it will let fuel pretty much just run past your jet settings

I just now noticed your reply, I hope the Tech thought of this... Wonder what the odds are? lol