ATV: 2005 Arctic Cat 400 4x4 FIS Manual

A compound of many issues all at once, so hard for me to isolate what's wrong now.

Recently the ATV was hard to crank, and I'd hear the starter seize up, and the starter died completely soon after, taking the solenoid out with it. I replaced the starter and solenoid. It was after this that I adjusted the valve clearances, which had probably never been done before in 1140 miles. Now it turns over much more easily, but is really chatty (ticking in the valve area) I am told chatty valves is normal and when they aren't chatty the clearances are to tight.

Prior to all of that, I moved back to stock exhaust. While doing this I rejetted the carb, back to a 142 main, stock pilot air screw, and replaced the clogged up slow jet and went ahead and put a new starter jet in it while I was there (all stock). I set the pilot screw to two turns out, per service manual.

I discovered the quad had idle issues when I replaced the broken electric choke with a manual choke. So I can close and open my choke at will now. The quad runs fine with the choke out, but stalls when the chokes in, but how it stalls is kind of weird. If I pull the choke out, after a few cranks it starts up and idles decently and seems to be happy. I let it warm up and as it does so it starts to idle higher (air is getting less dense, is now running rich, make sense I think?) So I close the choke. Upon closing the choke the idle goes way up for a few seconds, then starts to come back down, but it goes down to low and it stalls. It won't run with the choke plunger in the carb, only when I pull it out). So I bring the idle screw in, but to get it to stay running with no choke I have to have the idle screw in so far that I coast in first gear... I have gone through the pilot circuit in the carb, it's clean, I can blow air through the whole carb from every jet port, it took a cleaner bath, it's sparkly inside with all new stock jets. I even went through the diagram for the carb making sure all the orings and washers are in the right order.

This is my carburetor:

https://www.arcticcatpartshouse.com/...61a/carburetor

Here's a video of what the engine sounded like before valve adjustment and with broken electric choke after my last trail ride.


I have gone through the carb so many times, the only thing I think might be an issue is the diaphram on the slide that controls the slide vacuum, I have a really hard time seating it, but it doesn't look bad or worn. It does fold up on the sides a little (it's not uniform looking all the way around). But I'm not sure if the slide would effect the idle or the vacuum. I checked for air leaks on the intake manifold where the carb connects to the intake, it's air tight.

I'm not sure where to go from here. I could have compression issues and it's just not sucking fuel in hard enough. Maybe my float height is off? Bad valve seals from them being too tight?

 

Is it possible the engine timing is off, and it's just stalling out under normal gas load because it's not powering through the timing issue? I'm the 2nd owner of this ATV and the first owner didn't ride it much, it's probably all original chains, valve seals, etc etc. Pretty sure I'm the first one to mess with valve clearance on it.

 

Timing is based on the flywheel being keyed onto the crank. Can't get off. However, for a few years, Suzuki 400 motors had an issue with magnets coming off the flywheel. That would certainly cause running issues. I believe there is an upgraded flywheel available. Should be able to find a youtube video on the flywheel. Some folks fixed by epoxying the magnets back on. Maybe that's not your issue, but you should eliminate it. Sucks, because , otherwise, those Suzuki motors were great.I had a 2002 that was water cooled and prior to the flywheel problem, loved it. I would say the sound on your video is normal. They are a bit clattery.

 

I put a new carb on the quad and it runs great now and doesn't stall anymore. It's chatty, but as you said, it's normal. I have the valve clearance set right now, was never done before I did it so it was completely tight on both sides....