Zip That Grip

I picked up a 2003 KLF-250 for my son's first ATV a few months ago.  It had no compression and overall needed a lot of work.
To make a long story shorter, the major problems were in the head; mostly a bent valve.  We got it back and working and he was enjoying it until it just died.  Started back in to it only to find a broken timing chain.  I figured it had gotten stressed due to whatever caused the bent valve so no big deal...so I thought.  The problem is he was back riding it this weekend; probably has less than 4 hours on it since the timing chain was replaced and the same thing happened.  He'd been riding it down the trail very gingerly, we stopped to chat and he went to give it gas and it gave a little 'pop' and died.  When he hit the starter it was obvious it needed to be towed back.
Got it home to find the timing chain is broken again.  I really have no idea why.  It runs fine when running but now I'm gun shy.
Any thoughts and ideas would be appreciated.  He's getting pretty bummed so I'd like to get this figured out.  Just ordered another timing chain so we'll get back into it this weekend.

Took a ride up into the local mountains to check out the snow conditions before the next series of storms come thru. :coolgleamAc: Had a GREAT DAY !! :ola:
And if these next storms drop the amount of snow they are forecasting, the tracks will be going on ASAP !! :woot:
Hope you enjoy the video ... :seeyac:
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Get free Pro Taper MX Pillow Top Grips with the purchase of Pro Taper Evo Handlebars at Bike Bandit! Ends 10/17/13. Click here!

3rd annual event at Lost Trails ATV Park, Dunmore, PA
Attached flyer has the details

Save the Date! Sunday, September 16th 2012 For the Lost Trails 2nd Annual Bras for a Cause 1000 Dunham Drive - Dunmore, PA
ATV, SXS, and dirt bikes welcome. There are over 2000 acres of trails to ride as you please, all weekend long for regular admission prices, to benefit the Pink Ribbon Riders©. Find hidden bras throughout the trails and bring them back for a prize! The Pink Ribbon Riders is a 501 C 3 nonprofit organization whose mission is to provide direct financial assistance to both men and women breast cancer patients through fundraising events. With your help, during last year's event over $1,700 was raised for the cause. Pre-registration is available. For more information please visit the forum community at Ride Lost Trails | Lost Trails ATV Adventures| ATV Park | Off Road Vehicles or call 1-570-730-8131.