I removed every thing to get a peak in the cylinder since a new plug produced no firing. It is bad. The piston has a many contours to it and part of it has the texture of concrete,rough and gritty. And one small section on the outer perimeter has a normal look to it, shiny and flat.The cylinder is smooth to the touch.My guees is that the lean mixture melted the piston and it cooled into its deformed shape.The airbox had slipped of the carb.Who can tell me what is best to do?How much just for parts. Is there any way to make the sport stronger than before(stronger as in durable, it's fast enough for me)All first hand experiences please reply. I do not know if I can afford to repair it.I am depressed now.

 

Well, IF, and I say IF no part of the piston fell into the bottom end (you should be able to tell if a piece broke off) it won't be too bad.
I recently did a top end job on my Xplorer 400 (same engine) and cost was roughly $200.
Takes time to remove all the fenders & stuff, but there really isn't too much in terms of mechanical skill to do a top end job.
Basically, you will need to replace the piston. I STRONGLY recommend you have the cylinder bored, as well. THis will improve the life of the new piston considerably.

I got all my stuff from Ritter Cycle (www.rittercyle.com) and cost of a new piston, gaskets, and honing the cylinder came to right about $200.
Rick was good to work with, he sent me a cylinder already bored out, and then credited me what my cylinder was worth when he got it back (I think the difference was like $35 or so). Rick also gave me a few pointers about how to put it all back together again, to be sure I did it right.
About the only thing I would do different, if I did it all over again, would get a coated piston, instead of just a standard one. Longer lasting, and less likely to sieze.

Farmr

 

Before you put that thing back together with a bunch of new parts and assume it is ok, you might want to look for hairline cracks in your cylinder and head. I've never had any problems with my 4 wheeler but I had a SeaDoo watercraft that would consistently burn a hole through the #1 piston with a lot of grit and deformity like you describe. I put three pistons in it before I got smart and had it MagnaFluxed. A tiny crack in the top of the cylinder wall, too small to see by eye, was letting a tiny stream of cooling water in and forming a hot spot on the cylinder. A good engine machine shop can do MagnaFluxing but you'll have to do the chemical type. I have heard the magnetic magnafluxing is better but it obviously won't work on your aluminum head. You can buy a Magnaflux Jr. kit for around $30 and do it yourself. Just something to keep in mind.

 

Kep, what I did was get a cylinder/piston combo from Ritter. Upon recieving the cylinder, Rick checks it out, and if it is OK, he credits you back everything but the honing charge. If it isn't any good, you really aren't out anything, as you would have had to buy a cylinder anyway. Good Idea, though to have it checked out good. Those hot spots can cause damage you will never see if you don't know exactly what to look for.

Biggin, does the piston have a hole clear thru? If it does, you might need to have the bottom end gone through, as well. If not, I think a new piston/cyl honing should cure it. Check the head over close, though.

Farmr

 

I whimped out and took it the cycle repair shop.He said honing and new standard bore piston.No holes just deformity.Labor and all parts ;275$.That is no where near the price my mind had when first lifted the head off.
As for looking for cracks,should I tell that to the mechanic or not.I hate to be up in his face,he's a single man shop for 25 yearsand knows his stuff.

 

My opinion only.
Ask him if he warranties his work. If he says yes, don't worry about it. If there is a crack, it will show up pretty quick.

Farmr