250-500cc WR 300 compression

I'm getting ready to do a compression test on my WR. What's a normal range to be in?

New mine was 135psi, Rb head it was 175psi

EDIT just looked at my notes 155psi new

155 with std when new and 185 with race head

Mine is at 150 with throttle open. Should I re-ring it or let it go?

Re-Ring and a Race Head just cause I like to see you spend money

Keep in mind that with compression tester they vary wildly in read out. In other words what mine might read on my bike someone else's gauge will more than likely read different on the same bike. Best thing with a compression tester is to use it when your motor is new to get a base line and then use it to see how much compression you lose over time. To ask what it should be can be bogus since each of our gauges more than likely will give different readings.

Also when testing you should hold the kill switch on, throttle wide open, air filter removed and kick it 5-10 times.

I think I'm going to run it this season and see what happens! I'll keep a piston kit and gaskets on the shelf just in case...........

I would start measuring the ringgap and see if it's within tolerances, visually look at the piston and bore chamber itself for blow by, measure the cylinder and piston/wall clearances...things that you can note down as a baseline if you are indecisive on whether to do a top end.
Do the 300's have an hour meter? If not buy one and slap it before you do the top end as that is the most accurate way to guage the life of the motor.
Also depend on how you ride, how often ect...your average trail rider can go up to 150hrs before a topend vs a racer who will probably go up to 40hrs.

If everything is within tolerances but there are signs of blowby, just replace the rings, flex hone or use scrotchbrite to deglaze the bore.

#5 of compression loss for a 300 is nothing.....if it were a 125 and you were competing for points maybe.

It'll be easier to kick!

Thanks for the replies. I'll surely enjoy the lighter kick when it's 90 degrees and I'm tired from picking the bike off of the ground all day long....