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07 450 EXC, dead on trail, weird symptoms, need help please!

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Hello everyone.  Trying to help a buddy out with a bike, he has had some trouble with his 07 KTM 450 EXC (RFS).

 

Went riding last week, bike was running well, bogging a big at idle but would come to life fine with a whip of the throttle.  There is chance he had a bit to much oil in the bike, as he mentioned to me that when filling it up (previous oil change) it took more oil then normal (I dont know if this could effect what comes next).   Oil was just over sight glass.

 

Anyway, we road for approx 1.5 hours (bike was running fine), then hell broke loose.  On a hillclimb (tech in woods) his bike died completely.  no electical, would not kick start at all on the hillclimb.  In the process of trying to get the bike off the hillclimb (so we could work on it on a flat spot), it fell off the lowside of the trail and sat upside down for about 2-3 minutes, it took 3 of us to get the bike flipped back around and back on the trail.

 

We then pushed it to a flat spot, where after a few minutes of kicking the bike we realized it would not fire.  E-Start was doing nothing... no power (brand new battery by the way).  We then pulled apart the bike to find that the main fuse (15amp) was blown.  Had an extra fuse (75 amp) and used that as it was our only hope.

 

E-Start then would work (we did a 2 second test as bike was apart), so we put back on the tank/plastics and thought it was going to be good to go.  Then, when trying to fire the bike, it locked up completely.  E-Start would try to turn bike over but could not... kicking was dam near impossible.  Like the bike had seized.  We thought ring failure. 

 

At this point we went it to "get the hell out of the backcountry" mode.  Towed out, took a few hours, but got the bike back to car.  Then the bike would kick over easy (like it should) but would not fire.

 

 

Our first thought was rings.  we though maybe something happened with the piston/rings but after pulling the bike apart, top end looks good.  Valves are good, piston good, cylindar good.    Only strange things we found when tearing the bike apart were oil in exhaust (a bunch), oil in air box ( a little) and a oily plug.  everything else in top end was to spec.

 

Anythoughts on what this might be?  dont want to put everything back together untill we find the problem.

 

thanks for any info!

 

 

 

 

 

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Can't say why it died or won't start, but the oil in the exhaust and cylinder is because when it was upside down the oil poured out through the crank case breather into the intake, and got sucked into the cylinder. The cylinder full of oil is why it seemed locked up. Might as well refresh the top end while you have it apart. :)

Most dirt bikes vent the crank case to open air, but street legal bikes will vent into the intake or air box for emissions reasons.

Edited by sirthumpalot
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Dirty injector?

Only if the bike was 5 years newer.   ;)

Can't say why it died or won't start, but the oil in the exhaust and cylinder is because when it was upside down the oil poured out through the crank case breather into the intake, and got sucked into the cylinder. The cylinder full of oil is why it seemed locked up. Might as well refresh the top end while you have it apart. :)

Most dirt bikes vent the crank case to open air, but street legal bikes will vent into the intake or air box for emissions reasons.

Agreed.

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Can't say why it died or won't start, but the oil in the exhaust and cylinder is because when it was upside down the oil poured out through the crank case breather into the intake, and got sucked into the cylinder. The cylinder full of oil is why it seemed locked up. Might as well refresh the top end while you have it apart. :)

Most dirt bikes vent the crank case to open air, but street legal bikes will vent into the intake or air box for emissions reasons.

 

That makes sense.....

 

We got the bike back to the truck and it would not start... we did not have the correct wrench at the time to pull the plug. 

 

Bike is now going back together, I think it will fire just fine!  I'll keep everyone posted, thanks again for the help!

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Yes, when the bike was on its side or upside down, the oil filled the cylinder enough to seem as if the bike was seized. Once the oil is removed from the cylinder the bike will fire again. That explains the oil in all of those places. I would recommend venting the crankcase to the atmosphere to avoid this issue again in the future. 

 

The same thing happened to a buddy of mine's bike, except it was an S1000RR. 

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Dont vent the crank to the atmosphere. It will allow water and dirt to enter, specially when stalled or dropped  in creek crossings.  Install the one way check valve that is used on the 690's. They will lower overall crankcase pressure as well as stopping oil pouring out when the bike is dropped.

Also, tell your friend not to rely on the sight glass. They are rather inaccurate at times. At service time put 1.25ltrs and forget about it for 15hrs unless you know the bike uses oil.

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old school way to protect the vent to the air problem was to use a a small KN filter vent on the end of the hose...I use that in combo with a valve and no issues.

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The quitting of the engine might be due the wiring behind the headlight mask, particularly the kill switch circuit. The wires are small and easy to pinch and/or break. If the insulation gets compromised, there could be some intermittent no-run conditions.

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