I have a 2003 kfx 400 and i changed the oil in it but didnt torque the plug down and it ran out of oil what do u guys thnk it did to the motor?.... just rings? or

 

I did the same thing to a Bayou 220 a year ago...so that sort of thing does happen. In summary, I got it running again and it has been running good since I repaired it, so there is hope.

When it siezed, I pulled the cylinder and found that the piston had siezed to the cylinder. Also, found the wrist pin could not be removed. So, to remove the piston without splitting the case and taking off the connecting rod, I covered up the hole in the engine with a wrag, took a dremel tool and cut a slot in the top of the piston. Using a regular screwdriver, I split the top of the piston which exposed the wrist pin. I then saw a bit of aluminum had melted from the piston onto the wrist pin; using the dremel, I ground off the aluminum and the pin came out, no problem.

So, to get it going again:
1. Bored out the cylinder to oversize
2. Put in new oversize piston and oversize rings
3. New wrist pin
4. New gaskets

Fortunately, there was no damage to the tranny or clutch. If that had occurred, the approach would have been entirely different...

Started up great and is running fine.


Good luck...email back if I can help answer questions.


David

 

Did you lock the thing up?

 

yes he said his seized. Did yours?

 

no i bought it after the guy ran it out of oil for 500 dollars couldnt pass it up... it siezed but it turns free now

 

well how long was it run for after it ran outa oil...........it can do quite a bit of damage, you might even have to get your rod/berring replaced and it could have damaged the tranny too not to even mention what it could have done to the top end............

 

As soon as it started running out he turned it off

 

well then it probally didnt cause too much damage except for maby a slight seazure mark on the piston but i see you have the 440 kit so unless wiesco makes a overbore for that kit then you might end up haveing to get a whole new 440 kit but anyways my guess is it probally just needs a fresh bore and a new piston kit. also do a compression check and see if its up to par or not, this will help somehwat to dertimine the extent of the damage

 

Thanks

 

300ex90, if I were you I would do a compression and see what you come up with. If it comes up ok, I would put a teaspoon of oil down the plug hole and light it off.
Run it around for a while and see how it runs. If it runs good, go have fun with your $500 quad.
PS: You got a killer deal!!!!!!!!! Good job.