Ltr Noise

[IdahoMX]

So I just raced a mx race this last weekend and during the first race, Half way threw the motor made a loud whine for about 3 seconds and quit. I kept going and thoufht it was strange. While lining up to the last moto of the day the motor started to make a knocking sound at idle. Sounds like valves on a 400ex with a satge 2 cam. I went ahead and ran the second half and went a little easy on the motor. Pulled the oil filter out and there was a few small fragments of metal but nothing huge. KNow I dont know weather to tear it down or if its just the valves. Another odd thing is last time I had it out it was a little low on oil so I added 1/2 quart. Rode easy and didnt hink to much about it. I get to the race track and its barely showing on the dip stick again. Add about a quart of oil. Get done with the race and 2 days later, No oil on the dip stick. No oil leaking or running out the exhaust. Burning it maybe? FYI, Never have adjusted the valves. I am going to take the head off this weekend to see what I can see and adjust valves. Ideas?

[IdahoMX]

Pulled the valve cover off, No metal or any evidence of damage, Will gap valves tomorrow. Really dont want to pull the jug and head!

[ATVMX33]

did the missing oil go into the airbox...check that cause i got a quart of oil out of my airbox once...the cylinder was scratched pretty bad

[ammohog01]

As far as the noise goes, keep an eye on your oil pump. My motor started ticking and we thought it was the valves, cam chain. Tore it apart and the cam had seized in the journal and snapped the exhaust cam journal. Replaced the head and it did it again. Come to find out it was the oil pump went out. So guess who is getting a full fresh rebuild.

[IdahoMX]

I thought of the air box scenerio but nothing in it. Oil pump has some promise, I pulled the valve cover off and nothing out of the norm. I suppose if you pull the oil filter out and start it it would tell you if its pumping oil. It did squeel in the first moto but no real loss of power.

[ammohog01]

That is what mine did. First the squeel and then bad stuff happens. ha ha

[IdahoMX]

Found my problem. Checked valve clearance and all but 1 were still very tight to spec, 1 you still couldnt fit the next size up in but bigger gap then the others. OK there. Pulled the clutch basket out and walla, Broken gear on the oil pump like ammohog said. Why in the hell would they use a plastic gear for this I have no clue. ordering up another and should be good to go again.

[IdahoMX]

New question, The plastic gear is gone, But the main drive gear does not move when cranking, Should it? I tried to move it by hand and can not. I may need to dig into it further