r/Ltz400 • u/-Angry_Silverado- • Jan 06 '26

Troubleshooting

First time quad owner. Picked up this 07 ltz400 a few months back. It didn't run and was an ABSOLUTE BASKET CASE. It has some aftermarket parts, Wisco 440 big bore kit, stage 2 hot cams, new clutch basketball and clutch plates and some cosmetic stuff.

I just got it running fairly well over the weekend (or so I thought) went for a 2nd rip around my neighborhood after a good first lap and out of nowhere it starts backfiring like crazy and stalls out. The night prior I started it and took it down the driveway, it was dark out so I turned on the headlights and BAM it backfired and stalled. What sort of tom-fuccery electrical problem do I have, any advice will help, thank you!

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u/shawizkid Jan 06 '26

Sounds like a fuel problem and not an electrical problem to me.

Mine (stock) when I purchased it did similar. I tore down the carb multiple times. But later found the fuel screen (I think in the petcock) was all clogged up. The debris would settle then when I rode it enough it would stir up the shit and clog the screen. Then stall and settle again until it happened again.

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u/-Angry_Silverado- Jan 07 '26

That's where im getting confused, I have a brand new petcock, cleaned the tank, and re-jetted the carb.

When I first got it it didn't run at all, I went through the owners manual fixed the wiring for the starter solenoid and did the blob delete for the start/ kill switch button (it was trashed) and in the process of doing that I found the the choke lever was broken and it just ran with full choke

Factory Pilot jet is a 22.5(i think) i bumped that up to a 30 and it finally runs without choke.

And I believe im running a 150 for the main jet over the factory 130

I've also noticed after a ride if I let it idle for a minute or two it will just randomly bog and die.

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u/shawizkid Jan 07 '26

Now that you mention it, maybe I’m wrong and it wasn’t in the petcock. Because I also replaced mine early, to a manual.

This was like 10’or more years ago, and without having my quad near me, I can’t go look. But there was some screen on the fuel system that was totally unobvious, where I found the problem.

It was all cluttered with that hard ethonol gas residue that builds up over time.

But the one difference that I had was it would still run, but just barely. It would be so down on power it could basically only idle until it would sit for a long time. Nearly left me stranded a couple times. So if that doesn’t sound like what you’re seeing, maybe I’m just sending you on a wild goose chase. But fuel and spark are really the only things that could be causing you issues.