Author Topic: A7SS Valve timing g tip  (Read 177 times)

Offline Terryb

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A7SS Valve timing g tip
« on: 18.03. 2020 11:08 »
I'm trying to check the valve timing  and whilst I'm OK with check king the opening of the valves. I'm finding it difficult to get the closing sorted.

I've set the timing Mark's up dash to dash and dot to dot. I've opened the taplets to .015" and the inlet/exhaust openings are correct, but does anyone have a tip on doing the closing?
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Offline Terryb

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Re: A7SS Valve timing g tip
« Reply #1 on: 18.03. 2020 13:09 »
Don't worry Guy's,  I've sussed it and they check out +/- a few degrees.

Sorry for wasting time *smile*
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Offline Swarfcut

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Re: A7SS Valve timing g tip
« Reply #2 on: 18.03. 2020 14:25 »
Terry. I must admit this post puzzled me.  The only variables are the position of the timing marks on the gears, and the accuracy of manufacture of the camshaft. I would think it unlikely for there to be a problem with these components. The only trap for the unwary is the accidental substitution of Longstroke timing gears, as the basic  gear forms are the same but the timing marks and position of the peg drive for the breather sleeve are not. 

 Did you have an unmarked camshaft and you were trying to identify it by reference to published valve timing data?

 Swarfy.
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Offline Terryb

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Re: A7SS Valve timing g tip
« Reply #3 on: 18.03. 2020 17:14 »
Look this all came about when I was assembling my engine after having the timing side bearing line bored. Normally when working on my bikes I take many photos for record purposes but I didn't record the alignment of the cam/idler/crank pinions
So after completing the restoration I have been trying to start the old girl, without success. I've checked all the usual, spark, timing etc and I've started to doubt my memory regarding the valve timing, hence the thread.
Having never check valve timing before, I didn't have a problem with valves opening, it was understanding if you measure valves closing or being closed. I'm now happy that that the pinions are aligned (now have a photo) and suspect the non starting is possibly fuel. Haven't touched the carb for 4 months, so it needs attention 🤯
Thanks for your time
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Offline Swarfcut

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Re: A7SS Valve timing g tip
« Reply #4 on: 18.03. 2020 17:47 »
Easy when you know what to look for.  The engine requires a good few rotations for the marks to re-align, as the idler teeth are not a simple multiple of the crank or cam gears.

 No sweat, and thanks for the thanks.

Swarfy.
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