CBR 300R rear wheel locked up!!
 

So any guess as to why my chain eaither skipped a link or idk....but was omw to work this morn....cruising at about 45-50mph....starting hearing a kinda grindy/ draggy sound...befor i cld let off the throttle....bam!...back tire locked up...skidded about 30 to 40 feet and came to a safe stop off the road.

Kinda had to rock it a lil to get back tire free....was able to move it to a restaurant pk lot....from what i seen the chain is still attached but very loose....thinking sum happend from the drive sprocket......ugh just hopeing it didn't mess nothing up....

Only put around 500-600 miles on it since i got it....it was fully serviced befor i baught it...have only cleaned a lubed once...been keeping an eye on the chain slackness.....

Any ideas???

Bet that woke you up !
Your slack chain description sounds like you lost rear wheel alignment, and this caused the lock up. I’m guessing that the noises and sensations you were getting prior to this were due to the initial stages of failure.
When you changed throttle position, there was a change in tension at the fragile rear end and that was enough for it to go “bam”.
You need to have a look at your rear wheel spindle for tightness , your chain adjusters for symmetry and also, critically, being in the locked in position. If these are not as they should be, it could cause your issue. If you do find something that doesn’t look right just simply adjust till you get correct chain tension and wheel alignment.That’s where I’d check first. An easy fix if there’s an issue there. If all that looks good, then a good visual check over now that you have got yourself together after your scare should reveal what’s wrong.
Do make sure everything is 100% before you try and ride her again.
It could also be a few other things like a wheel bearing failure, (that can cause a horrible sound) a swing arm issue, (grab both arms and check for free play) suspension, brakes, sprocket......the list goes on.
Start with the obvious first and post what you find and how you get on.
Best of luck mate

You should be looking over tires and chain before every ride!

Got lucky this time. Next time may be different.