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Discussion Starter #1 (Edited)
Well, this tear down didn't exactly go as I planned...first a little background...

I bought a cheap Raptor from a friend needing money (Strike 1). Wouldn't start when I bought it and it generally looked kinda ratty (Strike 2). Carb rebuilds, new battery and L&A One-way. Start the bastard and poof! Blue Smoke (Strike 3)

Whatever. I'll rag the hell out of it (success), swap the piston/rings out, and tada! No more smoke!

Wrong.

First, the piston, rings, and cylinder are in great shape. No evidence of blow by from what I can tell, the bore is smooth as a babies ass, and the piston skirt is also in great shape.

FML.

Now, my concerns are the cylinder head and crank shaft. The crank looks like it got super hot (no oil, it burned it all off...) and probably killed the bearings. The crank does still spin by hand smoothly and freely. The cylinder head, however, pretty much looks like crap. The left exhaust valve is super cruddy, and the cam shaft bore has been chewed up and pulverized a bit.

FML. x2

On with the pictures...

Piston. Lots of carbon/oil crap on top. My first guess is valve stem seals.

Note the exhaust valve closest to the camera. Super nasty.

Chewed up cam journal...

Same journal, but showing the "lip" made...The camshaft somehow made it out of all of this ok.

Overheated, under lubricated crank...

Now...what are my best options? I don't want a 123234323342cc Raptor. This is a toy. Something to cruise with the lady friend. Relax compared to the dirtbike. The only thing I plan to "upgrade" at this point is the piston. Other than that, stock is best... Should I replace the crank? keep it oiled and wait for it to explode later? What do OEM cranks go for? I need a new cylinder. That's a non-negotiable. Prices?

Give me your thoughts, comments, suggestions on getting out of this without breaking the bank! Thanks!
 

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Nothing wrong with the crank, rod or piston, but your cylinder head looks like it has seen better days...............
 

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You have got to find out why the cam bearings burnt up in the first place, you don't want to replace and reburn the head, where are you located...........
 

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Discussion Starter #5
Northwest Florida. Cam bearings? umm....didn't see any bearings. Do you mean the journals? I'm pretty sure the head was damaged because of the lack of oil. My real concern is why did the thing start burning oil when the piston and rings are in such good shape.
 

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Sorry, that is what I meant, cam journals, they are built into the head, which are the bearings................
 

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If the rings are inded fine. then valve seals or a bad head gasket are the only things that could cause the loss of oil besides an oil leak. Pull the oil pump out and see what it looks like and also the screen in the oil tank. see if the screen is full of cramp and if the pumps gears are grooved/pitted.

The clutch cover hasnt been off recently before all of this right. If they forgot to seal up the ports in the cover that could cause your oil pressure issue, but not oil level.
 

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the rod angle on a stock raptor is not good at all. Most production automobiles are in the 1.7 range but our stock rappy motors are much less than that. A "severe" rod angle coupled with high rpms doesn't tend to help ring longevity. From what I see in the pics those rings are not in good condition, doesn't matter because you are going to replace them anyway. The head can be repaired but it would prolly cost more than a decent used one to repair it. If you just get yourself an 11:1 101mm Wiseco piston, a fresh bore for it and some new valve stem seals you'll be fine to get back on the trails. I would recommend you check the oil screen on the bottom oil tank line to see if it is clogged and inspect the oil pump, which you can remove from the clutch side after you take the clutch basket off. Heads don't usually get chewed up like that with adequate oil pressure.
The blueing of the crank journals is normal.
BTW, I grew up in a little town on Hwy 79.
 

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+1....If you send the head out for work, have a valve job done and have them check the valve guides and seals for ware. Looks like the head was run with no oil or contaminated oil.
 

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Discussion Starter #11
Thanks for all of the replies/thoughts/comments :thumbup:

I contacted Ken from the above link, and he thinks I have too much material removed from the journals for it to be repaired. He also stated that the he's seen damaged guides/stems from spring failure and the quad still didn't smoke like I had described. He firmly believes it was the bore/piston/rings combo delivering the smoking problems.

I guess now I'm in the market for a stock head (which Ken is trying to hunt down for me) and a new piston (again, with the help of Ken). We'll see how much this whole thing costs...

Thanks again guys, I'll check the oil pump screen and clutch basket shortly. There's no doubt in my mind that it ran low on oil/pressure. The evidence is everywhere...
 

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make sure you pull the oil pump apart and not just out. I bet the oil pump gears are trashed after all the metal from the head went threw it. I would pull the bottom end completely apart and flush eveyrthing.
 
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