poor performance

[wolfe 21]

I ride with a couple of the guys I went to High school with cause we've known each other long enough to trust each other, and I know they won't try to purposefully ditch the newby (me). Anyway, one of my friends rides a 2000 warrior that's stock, save for an HMF? pipe. Recently he's been having trouble keeping up (surprised everybody) because his bike is cutting out on him under throttle. When we got back and looked it over, his problem seems to be a stumble or miss at anything past 1/4 throttle.
If he lets it idle, pushs it past 1/4 and holds it, it will also do it in neutral. Basically the motor runs & idles fine, but under throttle it will misfire (or atleast that's how it sounds) at a regular spaced interval, like it's not getting a spark. We checked the plug wire and found the cap was loose, but tightening it didn't help. Also checked plug and found it was coated with a black smear that smelled like gas. And he just had the valves adjusted. Any ideas what might be causing this. Can't seem to find an answer anywhere. (I don't think it's a parking brake issue b/c the cable for that has been removed since before he bought it, and it used to run fine and smoke pretty much everything we had). Thanks, James.

[Busted Warrior]

Check the main jet. I had the same prob was running great and then I couldn't go past 1/4 throttle popping and sounding like it was misfiring. My main jet was totally blocked.

[hatfield44]

^+1

[450Rchaser]

Sounds like a good place to start. If you ever had the carb apart mite have a piece of trash in it and sucking it up when you give it gas. Seen it on a buddies 250r that made a gasket out of silicone.

[dave76]

Might be dumb but did anyone check the parking brake dosn't have a short, that only allows it to idle. Also I've seen on many warriors the reverse linkage somtimes isn't adjusted right and causes a short which causes the same issues your telling me. I would check those first.

[hypersnyper6947]

My money is on the parking brake. Get a parking brake delete off ebay and get rid of that stupid thing. They are such a pain in the ***. That is exactly what it sounds like though, check it at the clutch lever also. I zip tied mine so it would never work again, just the way i want it. Worst design ever

[wolfe 21]

well, I've looked into it. the main jet seems fine, clear and in good shape. carbs look clean inside, no dirt. reassemble and problem still there.
As for the parking brake, it's been disconnected at the lever since he bought it. Still has brake and line, just not connected to anything so there shouldn't be anything to trip the sensor as he's had the bike 3 years and this problem just developed.
Was wondering, could this be a torn diaphram or something. We found a crack in the side of the intake manifold boot and patched it with rubber cement, but it did not cure the issue. running out of ideas. Any help, greatly appreciated.

[Warrior#111]

have you checked your stator, or your coil? mine is doing the same thing and my stator was wrecked, my crank berring went bad and he stator put gouges in the mag, which caused poor fire.

[wolfe 21]

well, sorry it took so long but he found the problem. Turned out to be a bad frame ground causing an electrical issue that allowed the misfire. Tightened the bolt and everything is aces.

Thanks, James.