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Discussion Starter · #1 · (Edited)
Hi guys,

Doing the valves for the first time on my ST4S, and I have encountered an issue. I rented a tool kit (from ducati tool rental, great outfit) and followed the instructions and everything has gone well from a mechanical standpoint. Got the vertical cams and shims out and have made calculations according to the sheet.

However, I'm looking at the calculation for the new closing shims and it appears I need a 4mm closer. Seems big, have I done something wrong? Here are the numbers.

This is the left side exhaust on the horizontal cylinder btw.

unloaded gap: 0.18mm
loaded gap: 0.25mm
LT Snyder's recommended clearance: .10mm
original opener 2.7mm
original closer: 3.4mm

Calculated new opener: 2.78mm (for this, should I use a 2.75 or a 2.8?)
Calculated new closer: 4mm

Finally, if these seem correct, does Ducati make 4mm shims? there aren't any in the kit I rented...

Any and all feedback is greatly appreciated, I'm hoping to get the bike back together tomorrow!
 

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0.25 - 0.18 = 0.07mm, which is good for a closer. no need to change it.

if the opener is 2.78mm you need a 2.81mm.

there might be 4.00, don't recall if i have anything over 3.9 or so now. certainly never used them.
 

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Discussion Starter · #3 ·
Thanks for the post, it's been a long day and my subtraction skills need some work. Your calculation is right, I was way off. Ducati's specs for the exhaust closers is 0.10mm to 0.20. So a slightly tighter closer is ok, but bigger clearances are bad?
 

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Thanks for the post, it's been a long day and my subtraction skills need some work. Your calculation is right, I was way off. Ducati's specs for the exhaust closers is 0.10mm to 0.20. So a slightly tighter closer is ok, but bigger clearances are bad?
I've always been told tight clearances are bad so between the 2 choices pick the loose side.

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Not on closing shims. Tighter is better. Note Desmotimes's recommended clearance of .001. Now if Brad Black syas .007 is fine...then it is fine. Personally I like closers tighter.
 

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Not on closing shims. Tighter is better. Note Desmotimes's recommended clearance of .001. Now if Brad Black syas .007 is fine...then it is fine. Personally I like closers tighter.
I thought LT suggested .004 on both intake and exhaust an a ST4? And what I meant. by looser was it's better to go with a .005 or .006 instead of .003 if .004 is the bottom of the range. Or I may be misinterpreting which is easy to do for me.

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i use the following.

mm.

inlet opening 0.10
exhaust opening 0.15
inlet closing 0.07 - 0.10
exhaust closing 0.05 - 0.08

thou

inlet opening 4
exhaust opening 6
inlet closing 3 - 4
exhaust closing 2 - 3
 

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i use the following.

mm.

inlet opening 0.10
exhaust opening 0.15
inlet closing 0.07 - 0.10
exhaust closing 0.05 - 0.08

thou

inlet opening 4
exhaust opening 6
inlet closing 3 - 4
exhaust closing 2 - 3
Shit!!! That's good to know!

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