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Just bought an 05 basket case bike off Craigslist

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Just picked up a 2005 CRF450R off Craigs List for 500 bucks. The guy pulled the top end because it would not start and gave up. The cylinder is in good shape and still has good hone marks. The head is the only thing of question. The bike was run with a dirty looking K&N filter and the valves look dirty on the stems. But the head has some staining around the exhaust valves and where the exhaust port is. Looks like oil was cooked to the head. Would this be from worn seals or to high exhaust gas temps? The rest of the bike short of the forks needing service, is in great shape

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Edited by motoxr87
posting pic

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If you have the head gasket id bolt the head back on real quick and do a leakdown test. will tell ya what shape the valves/seats are in.

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Id say it was run lean and pretty hard over a significant distance. That black stuff is burned/coked on oil residue that was cooked on there from the exhaust temps. If it were me, Id just pop the exhaust valves out and check the seats and valve faces. Just because it got hot doesnt mean its ruined. What does the other side look like?

Is the combustion chamber white? The exhaust valves could be without a problem, but the chamber itself shouldnt be.

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The combustion chamber and the top of the piston are carbon-ed up and very black like it was running rich. It has a brand new plug in the head and the old one is not in the box.

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pull the valves, check the seats to see if they are cracked and/or pitted.

bigborethumpers has good valves and ready to run heads at a great price. Might want to start there, then get a new cam chain and tensioner and go from there.

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The combustion chamber and the top of the piston are carbon-ed up and very black like it was running rich. It has a brand new plug in the head and the old one is not in the box.

An extra rich mix could do that too if it was run really hard. Unburnt fuel in the port and pipe burning creating hotter than normal exhaust temps.

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An extra rich mix could do that too if it was run really hard. Unburnt fuel in the port and pipe burning creating hotter than normal exhaust temps.

how does the burnt oil or fuel get up there anyway? bad valve seals?

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how does the burnt oil or fuel get up there anyway? bad valve seals?

that whole area is an oil bath. The port is right there below. You can see the bump in the tappet area floor there.

That dark area there leading from the exhaust valve on the right side is the exhaust port itself. If you went hog wild with a port tool in the exhaust side, that's where you'd break through.

At about 4 o'clock on the left spring retainer you can see where the two ports converge and dump into the exhaust manifold part of the head where the header attaches.

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the cheapest way out is to buy pro-x intake valve kit from ebay they are stainless and come with springs for 100 dollars.a good machine shop should be able to cut the seats if needed and most of the time the exhaust valves can be reused.if so the labor should be about 100 depending where you take the head.the exhaust valves are 30 each for kibble white and check the head to make sure it is flat.most of the time this is a lot cheaper than buying a new head and unless you are racing the bike there is no reason not to run stainless valves also the stock seats are really tough unless you just think you want to spend money on the mold star seats. and run the stock ti intakes

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