SlammedRanger

Here is where we have options. You could buy a cheap knock off carb. They are around 50-75 dollars. I would suggest against this. They tend to not last very long and cause alot of annoyances with tuning. The cheapest oem carb i see on ebay is right around 200 dollars. This honestly is your best option. Option 3 would be roll the dice. But a used oem carb those look to be around 100 dollars. But you may have to buy a rebuild kit and take it apart and clean it this requires some good meticulous mechanical ability. You may also end up with a perfectly good used carb clean and in great condition. These are the struggles i go through everytime i build or fix a quad for a friend.

My bet why it stalled at random has something to do with it being lean from running the wrong carb. No offense to the person who put the carb on. But i doubt highly its jetted even close to correctly. I would struggle with dialing in the wrong carb for an engine and get it to run right. And having the exhaust leak and popping. I wouldnt read to much into the stalling until you get a 400ex carb on it and the exhaust leak fixed.

No worries! We have all been there! When i built my motor this last time. I did a full custom build. Custom piston, crank, whole 9 yards. Took it for the first ride down the road. Slow not getting on it i made it halfway back home and it shut off. I almost passed out i was so angry. Sat on it in the middle of the road with my head down just thinking what could have possibly gone wrong. I crossed all my T's dotted all my i's. Long story short. Gas was in the off position....................

Remove the black cover. The red cover is already removed. The black cover should just slide up the wire. And cross those 2 nuts on top with a screw driver and hit the start button while its crossed.

Ok from the top the wire that is burnt on the header is your coil wire. That goes to the spark plug. Want to make sure thats tied up away from the header. That is more of a fire hazard than anything. But not why its not turning over. The other is actually your clutch cable. Tie it away from the header aswell. Still though not the reason its not turning over 2nd picture wire does look attatched. Try wiggling it and see if you get a green light. You had a green light before all this correct? You are 100% sure its in neutral?(i know i know. We have all been here before) lol 3rd picture alot is learned in this picture. The clutch perch is stock. The 2 wires that are disconnected down at the bottom right of the pic are the wires for the neutral bypass. They have been removed which means this thing should start in gear so always be sure you are pulling the clutch when starting for safety as it will jump forward aggressively. If those wires were tied together it would only start in neutral. (It is possible i have this backwards in my mind lol) 4th picture all the important wires look to be attatched. It is possible your neutral switch could be going bad. There is a test for that. But i would try crossing the solinoid. It is the round piece with two big wires going into it. Mounted to the front of the battery. Take a flat blade screw driver. (Be 100% sure its in neutral roll it to be confident) and while crossing the terminals hit the start switch. See if it cranks over. If that dont work its 100% a neutral switch problem and we can go down the road to get it bypassed to get it running.

No green neutral light? If thats the case try pulling the clutch and see if it starts. There is a neutral switch down by the shift lever. Has one wire going to it. Usually green wire. It plugs into the neutral switch. If that wire came off or broke you wont get a green light when in neutral. The bypass is to pull the clutch. It should start as long as the clutch perch is still stock and not messed with. Take alot of pictures. We will get you straightened right out!

Check the fuse. Its back near the battery. I would also make sure its not just a loose battery connection. And no problem at all bud! Thats what we are here for. I can walk you through just about anything on a 400ex. I have had mine down to bare frame 3 times. As of rightnow it is a full custom stroker build. Around 440cc. Dont give up on the 400ex. Yours had a rough life. Someone at one point did some bad things. But it all can be turned around. Mine when i got it was rough aswell. They almost always are. Its a toy. People treat them that way.

In all honesty compared to what you have a stock 400ex carb would be an upgrade. All other options require some custom modifications to work. On my quad i run a 39mm fcr from an 07 yfz450r. But i have alot of time and effort into making this carb fit. It required alot of custom mods to do it. And i would bet i have near 500 dollars into it that mod alone. But thats a drop in the bucket to what i have in my quad.

Oh for sure! At first i thought it was a 450r carb which would be an upgrade. But who ever did this missed a very key aspect. The R. So this is a 450 utility quad carb which in term of bore size and specs is actually a downgrade. But its far from the worst i have seen on a 400ex or 450r that was "built" lol.

Its the wrong carb completely. They used a stock 400ex cable it appears. It should have a metal tube bent into a 90° angle with 2 nuts on it to lock it in place. The carb on it is for a foreman 450? I think? The pictures online look like the end of the cable sits down in a cradle and normally gets held in with the side cover so it doesnt rattle out. This picture they are 100% missing that cover. So it could rattle out at any point.

Yep P#18392‑mk4‑000

Well digging alittle deeper that is actually a carb for a trx450fm utility quad it appears. But that sound is almost surely from sucking in air somewhere. Either header gaskets. Could be the exhaust gasket between the muffler and header. Or it could be a bad seal where the carb goes into the rubber boot on the engine side.

Is it only when you shut the engine off? Or when you rev it?

Well that second picture is the idle screw(black handle). That is not the correct carb for that quad though. Think its a 04-05 trx450r carb by the looks of it. Which is an upgrade so thats good news. Turn that black knob counter clock wise while the engine is running. It should lower the idle.

Almost always with LG or Samsung appliances when they are doing something goofy its a control board issue. You can try the hard reset by killing power for 10 minutes and turning it back on. But if its decided to engage the child lock on its own it could be one two or three (depending on model) control boards. I wouldnt worry about it being a fire hazard or anything. From this odd behavior. If you want to see if parts are even available send me the M# and S# off it. (Should be around the edge near the door seal surface).

I would try adjusting the idle. Its a flat blade screw with knurled edges so you can turn it with your fingers also. Access from the left side of quad near the choke lever. If you turn it counter clockwise the idle should drop down. If it doesnt change at all then your mechanic put the carb back on and didnt adjust the throttle cable propely. In which case i would suggest finding a new mechanic. If they cant adjust a throttle cable i would be very weary of them doing anything. Its as easy as changing the oil. The back fire is probably because your not idling on the pilot jet but on the fuel from the needle so it will be super rich and that rich mixture is going into your exhaust and combusting. It should go away when idle is settled down. If it doesnt i would think vacuum leak at carb to engine side. Or leak at header gaskets.

Yep sounds like the screws rattled out of the actuator arm. It has 2 small phillips screws going down into the slide that attatch the arm to the slide. Accessed from the top 3 screw cover on the carb. They are hard to get tight. I usually put blue loctite on them. Dont use red! They will strip off next time you have to remove them.

Welcome aboard! That is a wicked trx250r! I would bet your list looks something like mine. It was to many lines long to fit in the signature area lol. Easiest to just say nothing is left stock haha!

Welcome aboard! More sport quad guys! Keep em coming! LoL!

Welcome aboard!

Them look real nice! One thing i never had the patience for. Painting anything. My paint jobs always look good at about 10-15 feet. Get any closer and you can see my rushed mistakes lol.

I had a DB and oem apart. There was absolutely zero difference between them. Originally when i changed mine i planned on ordering a rebuild for my oem one to fix. After finding the commutator was actually cracked in a few places i took apart the DB to see if maybe the cracks were supposed to be there. I confirmed they were not lol. And found they were 100% identical inside. Besides the cracks that is. Im thinking all the jumping and hard trail riding i was doing actually caused the cracks. The bearings were so sloppy i think it was banging around inside. The magnets were also chipped and cracked in a few places also.

+1 on DB electrical!

Sorry to have gotten your hopes up. I searched all my parts bins and stopped by our storage unit today and had no luck finding it. Im gunna say i must have trashed it at some point. Probably when i race cut my wire harness. Since its never able to go back on again.

Let me check my parts bin. I removed my stock headlight assembly years ago. It came off my 05 400ex so you may want to look up and see if its capatable. I will see if i can find it.