20 Most Recent 2002 KTM MXC 400 Racing Questions & Answers

could be headgasket gone

Sounds like a fuel problem. Try replacing the fuel filter.
Check all the lines and the tank vent.

I had a complete set of new seals installed last fiday and the pump appeared to be nice and dry? While sitting at the starting line for the district 37 grand prix last Saturday with the bike idling I looked down and fluid started spitting out of the weep hole?? I turned off the motor and it eventually stopped leaking. I went ahead and raced and it leaked a small amount more throughout the day??? Any ideas?? other than maybe it was a bad seal? or a bad installation from my local shop??James is probably right. The stock o-rings KTM sells for the carrier are 2-3 sizes smaller than they should be. I bought a bag of the corect (IMHO) o-rings. When you stretch an o-ring it gets thinner the further you stretch it the thinner it gets until it breaks. Since the o-ring is stretched thinner on the carrier it is not compressed properly it looses some of it sealing surface and can't hold the pressure as well. I think this is the reason most of the newly replaces water pump seals leak. That's why it will start leaking as the motor heats up and will continue to leak until the motor cools off and the pressure is gone from the cooling system. To test this warm the motor up and note how long it takes before the coolant starts leaking. Let the bike cool and then remove the radiator cap and warm the engine up if there's no leak then the o-rings are probably bad if it starts leaking then the seals are more likely the problem.,,,

u can take the current ones off by simply heating them to warm the cement then pull...if that doesnt work u could use a razor blade but bake sure that u dont cut anything. you could put the wire around the grip if u want its all up to u.

Yep normal. All my KTM's do that. I don't even hear it anymore because it's mentally filtered out. ;),

I have looked online all over the place hundreds of times to find manuals that you can download. I have never had any luck. But here is a link for one on ebay. Just click the link and it will take you to the right page on ebay. You can also get one at your library usually. http://shop.ebay.com/i.html?_nkw=manual+ktm+400+mxc&_sacat=0&_odkw=manual+ktm+400mxc&_osacat=0&_trksid=p3286.c0.m270.l1313

That would be like riding a fixed wheel bike.Think about how you will stop and start. Only hydraulic fluid will leak. Bad idea!

Question edited for clarity. That sounds like it is just a bad connection somewhere or possibly a bad switch. Remove the battery leads and clean the lead contacts and battery posts with a wire brush. Smear with Vaseline and reconnect. Remove the starter leads and do the same. Then it could be the Starter Relay https://www.google.com/search?q=ktm+450+sx-f+starter+relay+location Or Starter Button https://www.google.com/search?q=ktm+450+sx-f+starter+button+replacement ..

personnaly I would replace cylinder with new OEM

All dirt bikes have a VIN. It is on the steering neck. https://www.google.com/search?q=vin+on+my+ktm+300 ..

Have you checked battery connections. Run switch in the correct position? Checked spark plug for debris? Just thinking out loud..

Drain oil. Use degreaser to clean area. Use JB Weld & allow to set up properly before adding oil.

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Hi, try to see this link and looking for the manual that you need. https://www.pdfmotomanual.com/manuales/ktm/eng I hope to give you an help. Luca

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Hi, most likely your cdi unit or ignition coil needs replacing.

took me a min or two of WTF-ing to see pic and realize you meant a 2-stroke motorcycle..

try replace spark plugs

It's a bad seal of the head gasket. You need a new head gasket and to scrape every particle of debris from the cylinder head and cylinder surfaces that mate with the head gasket. Use the factory specified gasket sealing compound and do a clean job - no blobs or pools of the stuff. The head gasket should lay flat on the surface of the top of the cylinder, and you have to make this surface free of grit, leftover sealant and any other foreign matter before you put the head in place and torque it down. Start with the head bolts just finger tight and then go by the manufacturer's specs for the pattern and amount of torque to be applied. Usually it is recommended that you get to the specified torque amount in stages, going around several times and repeating the torque pattern until you get that maximum rated amount. This will prevent the seal from shifting or warping and should make the gasket seal perfectly. This is the old school method of doing this job. and I have never seen this fail to produce good results. Take your time, be clean, and you will have the results you want.

Check the clutch, adjust, clean, or replace

over full sump fuel getting into sump badly worn rings allowing excessive blow by