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blazen

Cylinder Head removal

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Hello, I just removed my valve cover and check the clearances and everything was in spec. Now I want to remove the head to replace piston, rings, and timing chain. I looked through the forums and found no detail on this. Do I have to remove the cams? Or can I just remove the tensioners, chain, 6 bolts and lift it off?

This is my first rebuild on this 01 426 since I bought it new. I took the motor off so I could work inside my house, anything else i should do while the motor is out? Any tips with this would be greatly appreciated. thanks-Alex

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You will have to remove the cams in order to get the cam chain off. When you pull the cams, its a good idea to remove the buckets and shims, and mark which shims to which valves, etc.

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It was deff. wise to pull the motor out it is much easier like that. I labeled my caps my shims for my valves and the head with a sharpie so I knew where each one came from. I would also suggest a manual if you do not already have one. There are a lot of critical torque specs you need to go by.

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The ball bearings for the cams sit directly over the left side head bolts anyway. The job can be done in the frame, and although it is certainly more difficult, I don't think it's even close to being worth the time it takes to pull the entire engine assembly for it.

Get a manual! You'll need it.

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I just completed a top end on my 2001 yz 426f and it was easy. You will defiantly need the manual for information such as torque specs, tightening sequence and ring clocking just to mention a few. I needed a air impact wrench to remove the rotor nut and also a puller to remove the rotor. A torque wrench is a must to reassemble the motor. The following link was also helpfull. http://dirtrider.com/tech/141_0412_yz250f_top/

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You can leave the head on the cylinder..... i did when i split the cases. Saves replacing the head gasket. Remove the 4 bolts (2 under cams and 2 outside) leave the other 2 smaller bolts.

You may not need to replace the base gasket... but i did while i was there.

Good luck.

Waldo

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You can leave the head on the cylinder..... i did when i split the cases. Saves replacing the head gasket. Remove the 4 bolts (2 under cams and 2 outside) leave the other 2 smaller bolts.
This is not good practice, frankly, on two counts.

First, the head surface is subjected to the two bolts on the far edge being the only ones at full torque. As small as this load is, it isn't good for it.

Secondly, the head gasket has already been crushed, and even though it will be torqued in exactly the same place as it was last time, because the cylinder is still bolted to it, it still gets retorqued to the same values, which means that it won't be compressed any more than it was. Not only that, it's going to be torqued out of sequence since the outer bolts are already tight, and surface warpage could occur.

The base gasket is too cheap, and too deep not to replace.

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