Another vote for stator electrical issues especially with it not registering above 14v charging.

Dont be affraid of rejetting a carb! The stock jetting isnt always the answer. Even a couple degree change in the temperature can make it bog. If you feel like it needs a smaller one put one in it.

Definitely sounds like an ignition issue. Fuel delivery problems are seldom intermittent. Start with the simple stuff. Disconnect the stop/kill switch from the primary lead of the ignition coil and test ride the bike . If problem persists, unscrew the spark plug boot from the secondary ignition coil lead and check the resistance of the boot. It should be close to 5k ohms. 4.5 - 5.5k is fine. Then before re-installing the boot, trim the secondary coil lead back 1/2". Make sure the lead is long enough to do this. There have been thousands of perfectly good ignition coils replaced when the only problem was the spark plug boot or the connection between the boot and the secondary coil wire. Other than these checks, it's on to the stator, pick up coil and CDI unit. Good luck!

Had a very similar issue with my bike , turns out it was bad wire in the coil and a few other wires on the bike that had corroded over . Fixed all the wiring issues and it ran perfect

I have an 08 sxf and the jetting of the flat cr carb always gave me issues. Either around camp or at the top of the mountain. I’d always be swapping jets . Once I switched to a lectron, “kinda felt like cheating “ I had instant power everywhere. Lots of love bro , love the vids

I can’t justify saying that the stator isn’t an issue, but I had issues with my 2002 520 falling on its face like that. Checking that the throttle position sensor is rotated to the optimum position helped, because that adjust the spark timing as the throttle turns. The thing that seemed to help the most was dropping the needle in the throttle by raising the clip position two spots, reducing the flow of fuel as you open the throttle further. Really hope you figure it out, love the work you do, keep it up!

Sounds exactly like what my bike was doing. And all I had to do was reset the ap timing and go down a size on my main jet, now she runs like a dream.

Don’t blame it on being a KTM because you can’t fix it lol it sounds like there’s a problem with the stater or possibly some loose wires in the mission system that will make it appear to be running rich because you’re not getting proper fire under load.

This era ktm was known for issues… all sorts of issues…. The new models are superior machines

I've never owned A dirt bike that ran in my life. I always fixed.& Repaired.& Worked on them for other people instead to enjoy instead of myself on that part of it all tom.

number 1 ya shouldnt leave your dog out in the rain in the kennel better invest in a invisable fence or take him inside to me if plug is good its stator or coil / ignition

KTMs are awesome bikes and require experience to keep them maintained. You cant slop shit around on these.

I had a 2002 EXC 300 2 stroke when I was a kid, I loved it! I was so comfortable riding it. I was racing my CR 85 before, when I switched to the KTM I noticed and felt a major improvement in my riding. I miss it, it looked exactly like yours.

Check valve clearances, and I would also pull the stator cover again and check the stator voltage output at the connector itself where it connects to the main harness. That bottom coil @ 17:00 mark in your last video looks very dark to me. It could be something simple as a bad electrical connection, someone was obviously messing with the electrical at one point based on the headlight wiring. Yes it does appear to slowly build up a charge, but that doesn't seem right. As soon as it starts up, if its charging properly, it should be reading high 13s - low 14s steadily, it shouldn't take a min or two to climb to 14. It should just read and maintain whatever it is outputting for voltage. From a quick google search, yours has symptoms of a dying stator, which can also cause engine running issues like yours is having. So I would find the stator resistance/output specs and start troubleshooting there. If none of that helps, then I would start looking at re-jetting the carburetor.

Great video joe you will get to the bottom of it I'm sure could be the jetting though my friend ha s 2 ktms and they are flying machines a bit newer right enough but I think once you iron this problem out it will fly good luck with it and hope you find the answer take care and your dog is a beuty mate 🔧🔧👍👌🔧

If it truly is a 2002 400EXC then the exhaust is wrong. The 2002 400 had two pipes out of the cylinder all the way to mid pipe before it went to one and into the silencer. Also, the muffler does have a spark arrestor in it. I owned one since new and just recently sold it for a newer model. A JD Jetting kit would wake that bike up, but I agree with others that the bogging issue is electrical. That year carb was difficult to get the pump set correctly as you have to bend a tab. Took me many tries to get it right. Good luck!

Checkout the vented fuel tank gas cap to it maybe plugged in the tip nipple to by chance from dirt.,or dust.packed inside of it to tom.

a lot of times I go too far vintage guy and I forget to think about you because you are the main attraction here this is your channel you are the SUPERSTAR!

Close to first, love the videos and i almost bought a project ktm to restore and sell but now , im gonna keep looking

I've had something similar happen before. Turns out when I replaced the diaphragm on the carb, i put the fuel needle through the retaining clip instead of under it. It caused the bike to bog under load. You can also see if you can adjust where the fuel needle sits on the clip and check for tears in the diaphragm.

I think the click after shutoff is part of the electric starter mechanism. Also the 18 inch rear wheel may help you determine 400 or 450.

New Regular rectifier - Cheap as chips - (Voltage should higher than that), also voltage drops slightly if anything when you rev it up - Also compression doesn’t last very long on the EXC’s - New rings and yer good - Get yer money back on that sprag clutch bearing - Still a good buy though.

Also checkout the inline fuel filter for being plugged up with debris.&sludge build up. One more thing to checkout is the fuel tank line inlet port for fuel flow blockage to like from rust.& Etc.

I think it could be weak spark Maybe coil or spark plug wire. Good luck Joe. I really like your videos.

Sounds like both the needle on the slide and the accelerator pump need adjusting. Awesome video though keep up the great work.

Hey bro, I love the videos, iv been binge watching for weeks😂, mad love from New Zealand, I was wondering if you have ever brought or worked on a WR250F, I recently brought one, and iv taken it to the shop to get the forks sealed and a whole $700 service, I just wana watch you work on a wr250f so I can take it all in and do my own repairs 😂, cause DAYMMMM workshops are expensive 😭😂, brought the bike for 1300 and iv spent 2k in the shop + including a helmet and goggles 😇

The hole in the fuel tank on KTM bikes for the choke is just for the extra fuel capacity of the tank, not "over-engineering" in my opinion.

20-year old bike. For a sanity check, try a quick leak down test just to verify there's no issue with valves or rings before getting too involved with carb adjustments or electrical system.

Correction, don’t buy ktm FOUR STROKES! The TWO STROKES are amazing!

Check the airfilter and intake track , if the carb is functioning as it’s suppose w stock jets and it’s pig rich then check the filter and intake track to make sure nothing made a nest or has it obstructed , if that’s Gucci time to check the valves and do a leak down test . I’ve seen cam lobes wear off which caused a similar issue .

My banshee used to do this same thing it was from a stator wire running along next to the exhaust and it would start up and run great until it warmed up then sputtered only on acceleration the wire would heat up and loose continuity and make it run poor

Recheck your valve clearance. Could be as simple as your intake is too tight and not clearing all the fuel into the cylinder when it opens causing it to pile up and get more and more rich as it runs. Other than that the timing could be slightly off, maybe the woodruff key bent slightly when you were having those one way bearing issues.

I have A 2000 400exc it's the carb, I never could get it to run right I bought a rebuilt carb for 300 and sold mine for 200. Best 100 bucks I ever spent. My original carb someone had added a long fuel screw and that model carb wasn't even designed for it. Made bike run super rich.

According to plug definitely running rich but I’d almost be willing to bet it’s maybe an intermittent spark issue on acceleration. My rmz kinda did something similar to this and it was in fact electrical

Typically manufactures give rich jetting. So the average Joe don't blow them up. Maybe this machine just runs rich. Id try dropping the jetting. The accelerater pump you usually don't get enough squirt. When they fail they are not squirting enough. Today's ktm are top notch. All the early (02-04)4 strokes the manufacturers were trying to work out the bugs of competitive 4 strokes. Not just ktm the big 4 Japanese too

The world needs leadership vintage guy and you are a perfect example of high-performance!

18:39 why does he just have a puppy siting in a cage outside in the rain listening to a loud bike?

I had a failing stator and it produced the exact symptoms your dealing with. It would start up and run good in the low rpm’s but would break up at high rpm’s like seen in the video. The stator does seem to have an issue with it based off those charging voltages. Should immediately jump up in voltage, not a slow climb as seen on your bike

You're really smart, it's a really nice bike, once sorted it'll be sick AF. I'm sure you'll get it.

Try messing around with the jets in the carb you never know love the content 👌 ✌️

Personally I would check to make sure it has a stock cdi on it and check the stator output as others have already said.

Take off air box cover. I put an exhaust and valves in my 450 and couldn’t figure out why it was doing exactly what your bikes doing. I took off the air box lid and it became an animal. It was restricted and wouldn’t rev out.

Have a good one man, keep it up!

Most of my friends take their bikes to the mechanic because they cannot figure the s*** out but you are a superstar God!

Check the pick up coil.,or the points to if that we engine has them on it to. They set between 0.15 to 0.20 thousands of A inch on top dead center to just about to open up. Accept still closed off until the crankshaft is rolled over again to fire under pressure.

My 2010 400xcw sounded like that right B4 it dropped a valve locking up bike. Head alone 800$. Oil was clean but there was shards in my airbox

Bike/engine diagnostics can be pretty simple if you just follow the basic steps and eliminate all the variables! ALWAYS drain and change the fluids (especially the fuel! It's an unknown quantity) draining the oil can give you a clue to overall engine condition. Inspect/Clean/Replace air filter. Do a proper compression test. Start with the cylinder dry! No oil, if it's low put a small amount of oil in the cylinder and retest. If compression comes up considerably your issue is "probably"rings and not valve related (4-stroke). Clean and inspect carb, if you're sure it's functioning properly, pull the ignition cover and check timing. In this case you have a charging system and it's not charging properly (low voltage) find out why! Inspect wiring harness and all connections. Buy a manual or research online and find the correct test procedure for the stator and coil. In this case I believe it's one of those 2 things but hard to say and only guessing without testing. The vibrations and conditions that bike components are subjected to can wreak havoc on wiring and electrical connections.ive also seen 4 stroke engines run erratically from improper cam timing ( excessively worn chain (although I doubt that's the case here)

Hi had an EXC 520 - I converted it to a Supermoto with stiffer suspension, upgraded brakes, 17 inch wheels front an drear, road tyres and different sprocket ratios and it was AWSOME!!!!

Sounds like a leak around the sneezer pin. The penal anacular spring should be at least 3 cat turds out and torque setting should be at minimum 30 uga dugaz!

I had that problem on my 110cc pit bike and it was too much gas coming into the cab try closing on the carburator flotor .

Had same problem on a yz450f. It had a 30 leak jet allowing accelerator pump to have to much pressure/fuel. Went to a 50 then raised needle. Ran like a champ after that.

So the moral of the story is if you have a KTM, take it to someone who knows what they’re doing

Could the previous owner have changed the float hight , attempting to stop the fuel from leaking? What notch was the clip for the main jet needle in?

You must be a crazy hard worker because it is so hard to focus on your job well you are doing all the camera work!

I have same volt meter , you have aftermarket headlight looks like a ufo product, great video , I was thinking of starting my on channel 😀

Could be a coil problem sounds like spark is cutting off

Had an 04' 450 EXC that did much better after replacing the mid-body gasket. Just a thought.

That click is the starter gear. Sometimes the motor spins backwards a little bit when it’s shut off. It’s completely normal my 2021 Crf250r does that and so does all of my other buddies bikes

Everyone i knew that has had a KTM worked on them as much as they rode them. Every now and then you get a good one that performs well but very rare.

Always check valve clearance when you buy a used bike. Most people have no clue about how often they need to be checked or even check them at all.

I love the job you did on the 350 Honda twin because that was a very sweet bike!

Try raising the needle in the carb slide 2 notches, if that improves things check the float height and set to factory settings then go back to the needle and set the best position by testing. Your problem is lean mixture not rich I think

Did you try running it without the filter? If it's rich you should notice a difference. It is weird though. Keep up the great work and keep those fires under control.

I had a kdx that was old and the slide needle and brass part in the carb that meters it was worn out, no amount of jetting would fix the rich problem. Figured it out years later....

After reading all the comments, it could be just about anything,,tough problem to solve,,, i so love the size of your tract of land , enjoy going for a ride with you on your land,,ride safe

replace mid body carby gaskets. if it has a slide check the gasket or o ring on that. I have a 01 wr250 that would still randomly when warm, miss on load and sometimes not start because of a bad mid body gasket and slide gasket. it wasn't even that bad but enough to make it do several weird things. another thing to check is try another coil in it. if the coils going bad it can break down when they get warm. process of elimination now.

Sounds electrical. Like the stator. Not giving constant spark.

Love all the great content, would love to see you ride an old cr500 💯👏🏾👏🏾

If your coolants bubbling that’s leaning towards a lean condition

Some of the KTM EXC's (Enduro Bikes) here in the UK had an option of a "long range tank" which yours look's to be one.

Disable the AP and do some jetting/tuning? See how it runs? Not sure how the pump is on that carb but there's got to be a way to adjust it to be off, right?

One thing you probably dont like about the ktm is the fork rake, they had a weird “euro” angle on the forks. Really weird issue you got there. I’m leaning towards ignition. But no telling how many hours are on it….sounds really bad. Curious what you find.

Ktms aren’t bad. And if I’m not wrong that’s a older one and the older ktms weren’t good… Never had a problem with mine and it’s a 2 stroke with 200 hours on stock piston

My ktm 360 with a gnarly pipe had a bad bog. I ended up after many tries going with a 178 jet instead of the 172 and second notch on the needle. Try going way rich first with 4 sizes bigger.

34:04 - I don’t think I’ve ever seen our Dude have to wait to pull out onto a blacktop road before. that ain’t Mom & Dad’s digs. this KTM is perfect for the channel, though. he may get 3-4 uploads before it runs like it should & less like any French automobile. Good Luck, Joe. that’s a big boy bike for Chuck anyway, now that he can benchpress you, while leg-curling his sister in law. I’d bet you’ll have the KTM POS running well enough, soon. cheers

My drz 400 did this plus cutting out , turned out to be the needle seat in the carb slide. Barb had snapped leaving the needle loose and bouncing around

Sounds like you need to adjust the preload on the suspension. Was it bouncy in the rear end or too stiff?

Hiya. My untrained but been mucking around with motors my whole life gut instinct says ignition issues. Also in my old shop we used to say KTM stood for Keep Throwing Money lol. Dont know what KTM parts are like in the US. But here in NZ they are stupidly expensive. A set of genuine valves and springs for ya 450EXC would be over $1500!!!! So yeah, hardly ever used genuine parts in the things.

You need to route the throttle cables correctly they should go between the handlebars and the tank I can hear the throttle sticking when you turn the bars.and it actually sounds lean at higher rpm definitely do the mid base gaskets on the carb it's sucking air .

Maybe Vinny can find some matches somewhere! Your a legend Brother, keep up the good work, I'm looking forward to a road test on your Gandhi's Goldwing. (;{~

Check valve clearance. I have a 150r that’s having the same bogging/cutting out issue. The valves are off. I dropped the needle all the way and it quit for about 10 hours of riding and it just came back as the valves got worse. Valves are definitely out of spec on that bike though.

In my days of racing motocross it was always the ktm,s that broke down. Seems nothings changed.

The sound you hear when it shuts off is very common in modern 4 strokes. It's the decompression snapping back.

I wish I had a family like you vintage guy and the only reason I am so fantastic is because I never listen to my mother!

I'd try checking out the petcock filter screen out good 👍 to.& The petcock seal for tightness to.

Jo I think you just need to adjust the valves I has the same problem then I adjust it and runs like a beast

If it’s rich turn ur a/f screw a bump out. Or adjust the clip on the needle down a notch. Regardless of accelerator pump, you can meter the fuel intake. If it’s got a reed cage check reeds as well

If you can I'd test the stator and coil cold vs hot seems like it's either blowing out the spark or has compression loss through the head gasket or something and maybe it's causing it to give false rich plug readings.

Always go back to what an engine needs to run. But it needs more than that to run properly! Air/fuel/spark. Air needs to be adequate, fuel needs to be fresh and metered correctly. And spark needs to be adequate as well. And timed correctly. Just because you get spark cranking an engine does not mean it's enough spark or at the right time for complete combustion. And it also needs enough compression for proper combustion. When you're dealing with a 4-stroke more variables come into the equation. Valve seal, valve timing and adjustment. And then there's always the possibility of air/vacuum leaks.

Could be a coil breaking up had it happen to me as it warms up an gets hot it gets really bad I'd check the valve clarence to shes sounds a little tight in the top end but my bike used to do that an I replaced everything then we tested a new coil an the bike ran better then ever before would sit an idle all day long but as soon as you put it under load it would break apart just like this an sounds like its smacking the limiter but it's really breaking up spark

Sounds ignition related. It’s not bogging, it’s breaking up. Cdi or weak coil. Ohm out the coil and if it ohms out good replace the CDI. Sporadic and weird is usually CDI or in the automotive world ignition module.

My ktm 525 my biggest problem was the mid gasket on the carb it ran before I changed those gaskets but not good after it ran great. Not the bowl gasket but mid body gasket on carb

I had an ATC 90 I bought as a box of parts. Got it all together and it never ran right, like your KTM. Turns out the box of parts came with two ignition coils. I picked the wrong one. Put the other one in and it ran perfectly. .

Did not expect the turkey to make a cameo lol

Did you get it running?, I had the exact same issue on a Honda xr75 , the sound and boggs were identical, I rebuilt the carb and blaster the jets clean with compressed air and added a new air filter , and the issue was fixed

My cr125 had that bog issue, turned out it was low compression. didn’t you have it at around 100psi? Would that be the issue maybe

If it is anything like the old Yz/Wr426's that yamaha brought out in the late 90's early 2000's. The carburetors on those were renowned for having a similar issue. There is a mod you can try for the fuel pump called the BK mod. It can be done several ways but essentially it just stops the arm from pushing the pump all the way so it doesn't squirt as much fuel through during acceleration. If you have exhausted all other basic options. Try the BK mod. I have several 400's and 426's and i have had to do it to every one in order to get it not to bog.

Recently bought a honda ct 90 for 250$ no carb or anything but I zip tied a battery to the side of it Cleaned the points and it had spark so I sprayed some starting fluid in the intake and it popped off for a bit needless to say I'm happy with it.

What happened to the kx that cought fire, do you still have it, would love to see it fixed, my brother just pick one up and is boring it out

I had similar problems on my ktm after i got carb rebuild. It was float height. Had carb on and off a few times before it was right.