I just got a new rear shock and my HPD pipe put on and i was riding arround not more than an hour and i blew the motor. I havent had a chance to look inside yet. The bore was new last summer. The only thing i can think of is that it got way too hot cause my jetting was lean. But the last time this happend it was totally stock, and the jetting was perfect, and the bore had about 400hrs on it. Im getting it bored and a new piston and rod installed. Possibly some porting and getting the head milled. If i get the head milled will i need to run a higher octane? (the highest sold arround here is 91)

 

Same thing here, mine was an 02 xplorer. Completely stock, started to bog, then died. Couldnt pull the pull start, completely frozen. Pulled the plug, it was pitted, grey, and burned. No idea what caused it.

 

well heres the scarry part i can pull the rope w/ one arm! Im gonna guess the rod is totally disconnected from the piston or the crank im not sure which

 

You may have a hole in the piston if you ran it lean. That would account for no compression and easy to pull.

 

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I had the dealer fix mine, I don't like messing with the internals of engines, if they screw anything up they can deal with it. It was 400 for the whole repair. But now it sounds really high pitched and pingy. Maybe the new engine still on break-in?

 

you think ill need to re-bore if the piston has a hole? ///////// mine was realy high pitched and pinged alot till i got it broke in but its still a lil more high pitched than it used to be

 

More than likely but make sure first. Take the cylinder down to the dealer and have him check the bore for trueness and go from there. I wouldn't tell him what happened just see if it needs to go to the next bore. If it was a real bad meltdown then it will probably be pretty obvious what happened.

 

thanks for the advise by the way thats one helluva scrambler u have there duneaholic! ive seen some footage and you were spankin those yama 450s pretty bad!

 

Thanks for the compliments. It does suprise some yammy owners that's for sure.[img]i/expressions/face-icon-small-happy.gif[/img]

 

If you have actually 400 hours on the top end then it is more than likely ready for a rebore again. 40 hours would be a different story. Like Duneaholic said you definitely want to have the bore checked for roundness and size. If the piston has a hole melted in the middle then make sure to clean out the bottom end real good. More than likely it stuck the rings to the piston on the exhaust side.