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Rocker shaft woes


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Folks, since a few months I've been dealing with increasing tappet noise round cyl 1 or thought to be so. I adjusted the valve clearance a couple of times but no joy. Today i pulled the shaft assembly and replaced with a spare; re-torqued the head and...problem solved.

Upon inspecting the old shaft assembly i noticed that the clearance between the pedestal and the rocker arm is only 0.3 mm with the end spring fully compressed at cyl 1, which is way less than at cyl 4 (~ 4 mm). The other thing i noticed is that the rocker arm has a slight lateral play on the shaft - barely noticeable but there is a play.

My question: Is there a recommented end-float on either side of the shaft ? The obvious answer would be that it should be the same on either side but by the look of it i have about 4 mm float on both sides of the spare shaft.

 

As always 

Stef

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Edited by Geko
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If ye look closely, then yee,l find a double thin spring wesher,

or there should be  one in thea, unless its been took oot.

this wee thingy holds the rocker arm against the rockers ped

 

its nowt t,worry aboot

 

M

Edited by GT6M
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A long time ago I noticed that on my engine some rockers were not acting centrally on the valve stems. I stripped the shaft and by suitable use of shim washers reassembled it so that all eight rockers were centred on their valve stems whilst all had sufficient minimal side float to allow for expansion.

Tim

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I recall reading in a Triumph motorcycle bookthat the contact point should be offset to one side to encourage the valve to rotate slightly each timeit is opened/closed.  

Have no evidence to support this claim but maybe some of the racing fraternity may be able to confirm/deny it's veracity.

Laurence 

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4 minutes ago, Mr Blue Sky said:

I recall reading in a Triumph motorcycle bookthat the contact point should be offset to one side to encourage the valve to rotate slightly each timeit is opened/closed.  

Have no evidence to support this claim but maybe some of the racing fraternity may be able to confirm/deny it's veracity.

Laurence 

Hi Laurence,

that is certainly true for the tappets which are off-set on the cam lobes. But I do not see how this would also work for the valve stem.

I stand to be corrected.

Waldi

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