In the event of running a motor low on oil

[.c.]

..what are the typical first areas to suffer damage? Crank,big end, small end or cam journals?

I have a clattering sound from the left (sprocket) side once the revs are brought up apx 3000-4000 rpm. It doesn't smoke. When riding it sounds like loose top of a tank bag is flapping. It started suddenly after hard acceleration. Beyond the noise everything else is normal.

I've pulled the intake cam journal and it doesn't look like it suffered much damage- there is some minimal scoring. I expected worse. The exhaust manifolds don't look like they have any leaks. The stator appears okay but there is a small amount of oil inside its housing. The intake valve on the left (noisy)most side of #1 cylinder looks like it has a bit of carbon build up and is a little wet. Most of the intake valves have some carbon as the motor has apx 20000 miles on it.

If the low oil situation didn't cause damage,  what could the noise be indicative of? I'm hoping that the damage is  confined to the top end.

c

[JW OLDBUSA]

How low on oil was it when the noise started? Did the light come on?
If It's noisey I'd take it apart to find out why, so not to take a chance of doing more damage. Don't guess.

Mine, during a dyno session started to knock a little, I took it apart and the last thing I noticed was 2 pistons had such a large carbon build-up from leaky valve seals, that the carbon was hitting the head.

[.c.]

Less than a liter. The oil light did not come on until after it was making noise. I had to ride it
about 15 miles at low rpm to get home. Initially I thought my tank bag was flapping loose.

c

[.c.]

I had refilled it and........it still made that gawdaful sound. No smoke out the pipes. That was last August and I still haven't got my mojo back yet, lol.

The miles on it were part throttle. Pity the light didn't come on before the noise. Pity I didn't check the level of the engine "that never used a drop of oil".

c

[mike46]

See, I am thinking that even with a liter of oil in it, you hadn't yet reached total oil starvation

I have to modify my earlier statment...I read it as if you were only down 1 liter...not that you had less then 1 liter in the engine. That is bad as you could suck air at given moments.

[DaveO]

#1 or #2 rod brgs go first....and will make noise on decel usually, light knocking sound at first.

If you only had less than 1 liter in it while under hard accel my guess is the rod brgs....

Dave

[tampated]

There is a simple way to tell if your bearings are going out.  Look at the oil when you change it.  Do you see any metal flakes gold / copper?  if so, then pull out the crank....

[Quijinn]

Thats the bitch about bearings, once they go they keep going. I have had bearings score and was able to to in car repairs without pulling the motor, but that is for 6500 rpm motors.

[shiphteeey]

Stupid me forgot to screw on the oil cap/dipstick on my F2 @ a trackday last year.  I opened it up to cool it down between sessions....

Well I went out...did an entire lap around VIR (Full course)....thought I was rossi cuz no one was passing me....finally @ a control rider caught up to me and pointed me off the track....

oil all over the exhaust, footpeg, even tire, swingarm, etc.

Go to pit in, added about 1 full quart!  @ 13,000 rpms the damage was done....by the next track DAY (it seemed fine the rest of the day) I couldn't get past about 110 mph on the straights where  was routinely hitting 135+

Started clanging....thought it was valves or cam chain.  Had that diesel motor sound, clangy.

Shop threw on a new cam chain....still messed up....diagnosed as either crank or rod bearing failure due to oil starvation @ 10-13.5k rpms for 2 min or so!

Good luck.

A.