Whining noise Kx450f.

If it has three hours on it take it back to the dealer and ask them to check it out.

Bike info helps,. Year, mods,stock?

Based on the description of the problem, I'm going to guess it's a newer KX450. I'm pretty sure this has been an issue since about 2012. Some of them squeal when the clutch gets hot. The issue is the pushrod not allowing enough oil to pass through so it can get quite noisy. There is a procedure for modifying the push rod but I run 1000-1050cc's of oil and never had the squealing issue. A few friends of mine who had the issue also ran more oil and it went away. I would try that first. If that still doesn't work, there is a thread over on thumper talk about the modification. I believe that some dealers are even aware and can do the mod for you. But try a little more oil first.

Mine has been doing that for a while only once in a while though I was wondering what the problem was or if it was no big deal

+1 on the oil. do some research. I have seen it fix your issue. not positive on the amount.

I have a 16 that was making the whining noise when it was hot or under a hard load. File down each end of the clutch pushrod so it has 2 flats to allow more oil through to the bearing. Also adding 100cc's along with the filed pushrod helps. To access the pushrod pull off the clutch cover, remove the outer plate, then pull out the pushrod. Pretty simple process and works effectively.

New KXF. Before I even break in.
1. Pro Circuit Clutch Springs
2. Acerbis Chain Guide/ Slider Kit

David
774 Chaplin Kawasaki
Factory Backing
Factory Seat
Acerbis
Dunlop
MX Engine Stand
Matrix Concepts

Mine did it for the first couple months then stopped. I do have a comment on the counter shaft turning a bit hard. I noticed my rear wheel doesn't spin as easy as my other bikes. While replacing sprockets I noticed the counter shaft seamed like it had a drag to it. I put a socket on the nut, hit it with a hammer and it turned much easier. It always ends up having the drag feeling after I ride, but just seems weird.

alot of them do this, ill get you pics on how to fix it, every 12+ kx450f that comes through my shop for builds or work gets the mod