Locked up DRR70

[Hemi636]

My son's 2009 Drr70 locked up last night. I was wondering if anybody might know what caused it. It is a liquid cooled model that is stock except the oil injection was removed, and it has an after market pipe.
Here's what happened. He was going to race at the local county fair last night, and the quad was running good in the practice session. After practice he drove it back to the truck and shut it down. about 90 minutes later his class was called to the staging area, and it started up just fine. He was driving through the pits (low rate of speed) and it shut off. We couldn't get it started (the kick starter would not move) We pushed it back to the truck, and found that the electrode on the spark plug was smashed. I guess something must have let go, and the piston hit the plug. The same plug has been in the quad for about a month with no problems.
Does anybody know what may have caused this, and what is involved in fixing it. I've only had a cyclinder off on an air cooled 2 stroke in the past, and if the case is going to need split I'm not confident that I can handle that. Thanks in advance for any replies.

[Coley'sdad#8]

sounds like a wrist pin bearing let go, needles went to top of cylinder getting slapped up and down by piston and smashed plug electrode or a ring. either way it will be something along those lines so tear the top end off of it and see. what color is the plug by the way??????

[travis rimmer]

almost a sure bet its the crank bearings they go bad sometimes maybe not enough oil take your top end off and feel how much slack your rod has side to side is normal but should have no play up and down this is what happened to your spark plug

[bulldogfallon]

You need to pull the top end off to really see what is broken....

It is surprising what you will find sometimes

Depending upon what happend and how much debris there is will dictate the need to slip the cases (usually a good move, but sometimes you get lucky and don't need to)

Take it apart and post some pics

Good luck

[Hemi636]

Thanks for the replies. The plug was brown, and dry, which was what I thought was good from what I had read.
I think I'm gonna try and do this myself. I'm gonna have to learn my way around these engines sooner or later since I have two boys running them, & I don't have an unlimited amount of funds to pay for someone else to do it. Wish me luck, and I'll keep the progress posted as I get into it.

[skyeryder]

They aren't that bad to work on once you've done it, just take your time.... that's always been my biggest problem not enough patience.
when putting it back together remember that your working with small bolts and go by the torque specs.

[fomospede]

haha small bolts :D , those piston circlips are delicate and there is an unspoken method to installing them :grr: take your time and lay it out in order of disassembly :) :) :) :) :) :) :) :) :) :) :) :) :) :) :)