Part 28 Reassembling the Cylinder Heads ...

Introduction ...

This page contains photos of the process of reassembling the cylinder heads that belong to a ROTAX 912ULS engine (built August 2006).



ROTAX 912ULS reassembling the cylinder heads

Image 1

Here we have the first cylinder head disassembled and back from parts cleaning ...

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ROTAX 912ULS reassembling the cylinder heads

Image 5

The first job is to replace the valve spring base shims, one for each valve ...

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ROTAX 912ULS reassembling the cylinder heads

Image 6

A sample shim on the bench ...

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ROTAX 912ULS reassembling the cylinder heads

Image 7

Having lapped in both valves so that they seat in their respective valve seats correctly, replace the inlet valve and exhaust valve by oiling them and the valve guides and then pushing them though from the combustion side of the cylinder head ...

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ROTAX 912ULS reassembling the cylinder heads

Image 8

From the combustion side here you can see the two valves in place ...

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ROTAX 912ULS reassembling the cylinder heads

Image 12

Looking at the upper side of the cylinder head, having replaced the shims we can now replace the valve springs and valve spring retainers.

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ROTAX 912ULS reassembling the cylinder heads

Image 14

Now the valve springs are ready to be compressed with our Rotax valve spring compression tool and the pair of valve cotters replaced ...

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ROTAX 912ULS reassembling the cylinder heads

Image 18

And here the valve cotters are back in place ...

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ROTAX 912ULS reassembling the cylinder heads

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The next job is to replace the rocker shaft and rockers ...

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ROTAX 912ULS reassembling the cylinder heads

Image 23

Oil the rocker shaft journals, the rocker shaft and the rocker arms. Refit the rocker arms taking great car to ensure that the rocker arm gets reunited with the original valve and pushrod it was broken in with (if you are not replacing these parts) ...

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