Weird Seizure scare this weekend

[Birgster]

My 01 300mxc scared me this weekend and I'm still puzzled about what happened. Any comments appreciated.

I mixed the oil at 50:1 for the first time. My friend and I ran the bike for two hours taking turns on large Grand prix track. Didn't give it a rest. The bike ran flawless when he suddenly shut down and rode the bike back to where I was sitting and watching.
He explained that he heard a knocking on the top end and the bike started to bog.
I started it and went for a quick ride and the same thing happened. Not a loud knock, but the bog till I let off the gas. Mostly at the low end.
We were low on gas, but still crawled the bike back to the truck. At first I thought it was to lean and started to Seize or get hot. At home I went for a top end run and it was running like it was missing then shut down quickly and checked the plug. It was not running lean. No white smoke, nice and brown.
I'm starting to think that it was starving for gas and this is where I am a little confused. Will the bike run like **** on reserve or really low on gas? I made all the jetting suggestions from this forum, 172 main, pilot and needle, was 50:1 to lean for the 300Mxc? I checked the main jet, clogged petcock, air filter and could find nothing. It seems hard to believe that heat seize would start after it ran for two hours with no problem.

Any thoughts?

rb.

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R.B.
When ever she starts to bitch, I go riding.
00, DUCATI 996
01, KTM 300 M/XC

 

[Layton]

If it was low on gas, low enough that it was actually running out, that would cause a lean condition. No fuel, all air.



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[Strick]

Layton's comment is right. A 172 main at your altitude and temps is lean IMO. This does depend on the needle you are running. Were you running WFO on this track for very long?

I would do a compression check, finger on kill switch, throttle wide open, 10 kicks - cold. If this comes out 160 or below, I would guess some sort of seizure occured.

Pulling the top end is very easy you don't have to worry about resetting the power valve. If you decide to pull the jug post back and someone here can walk you through it, if you don't have the shop manual. Good LucK



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Strick '99 KTM 300mxc, AMA & BRC member

 

[Birgster]

Strick,
What do you mean by WFO? sorry about the acronyms.
I wish I had a compression gauge. Still in warranty so I could talk to the dealer about checking it out.
I'll go back to 40:1.

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R.B.
When ever she starts to bitch, I go riding.
00, DUCATI 996
01, KTM 300 M/XC

 

[Strick]

Wide F------ Open

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Strick '99 KTM 300mxc, AMA & BRC member

 

[Birgster]

That's what I thought it meant. No we were not wide open, but was on the pipe some of the time. Lots of turns and hills and berms and no wide open straight aways.

I'm going to fill it up with new gas tonight and take it around the block and she how she runs. I'm starting to think that I didn't put it on reserve and it was starving for gas.

This is the second time I thought I had plenty of gas and had to goto reserve. I'm thinking of changing the petcock to that of a SX.

------------------
R.B.
When ever she starts to bitch, I go riding.
00, DUCATI 996
01, KTM 300 M/XC