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Valve spring shim settings

V

Vintage Don

Just got it firing!
Joined
Apr 14, 2019
Messages
14
Location
UK
I am in the process of refreshing the cylinder heads on my 2008 California Vintage. Does anyone have the the valve spring setting dimensions so that I can set the pre load shims? Many Thanks Don
 
kiwi dave said:
Isn't that something you have to measure for each valve?
Click to expand...
That's correct Dave. it's to set the correct spring force for each valve which is achieved by placing shims under the base of the valve springs. It tends to be around 10% compression of the free length. So ideally I need the spring free length as per factory spec and then the factory tolerance for spring preload. On the Guzzi both inlet and exhaust valves have the same preload.
 
Last edited:
The spec. on the "round-fin" engines was 35.700-36.000 mm, but I'm not sure if that changed for later engines.
 
To address the original question.

I replaced my springs (plus camshaft and followers) on a couple of 2002 EV Touring bikes. There was a special tool supplied which provided a reference point for measuring. You could possibly rig one up.

From the instructions:-

Using a gauge, measure the distance between the cylinder head and the reference point. Take note of the reading "A". (for example A = 89.2 mm).

Measure the distance between the valve stem end and the reference point. Take note of the reading "B". (for example B = 45.5 mm)

Calculate A - B - 43.2 = New shim to be fitted under the spring. Using the supplied shims, you should use a combination until the the value determined above exceeds the value calculated.

I could see you some scans of the pages involved if you provide me with an email address.

However, the heads on the Vintage may not be the same, as they were fitted with Breva 1100 versions I recall.

The real problem with the EV Touring was the valve springs originally fitted were way above specification (i.e. too strong) which lead to premature wear of the cams and followers. It took Moto Guzzi some considerable time to sort this out, and offered other fixes before deciding on the final solution. The cam also had a different profile with a ramp introduced to reduce the impact.

I owned three EV Tourings, I did two, the local shop did the first one as it was purchased from them. (They didn't do a thorough job IMHO). The other two I purchased from Moto International, and it was them that sent me the kit and instructions.

Hope this helps.
 
Amboman said:
The spec. on the "round-fin" engines was 35.700-36.000 mm, but I'm not sure if that changed for later engines.
Click to expand...
Thanks Charlie. I spent most of last night going through square barrel manuals trying to find data having first determined which models had the same valve spring part numbers. Many are silent on spring pre load but some do have the info. In the end I came up with 2 settings the one you have supplied and the one in the uploaded file at 34.7 +.35, so I installed the valves without shims and measured the installed length. All were less than the 36-,03 spec so I have now shimmed them to the 34.7+.35 setting as that is where my logic has taken me. What I did not say in my original post is that my engine has only done 8000 miles. I stripped off the heads and barrels as all the paint was flaking so I wanted to vapour blast them. In dismantling the heads I thought I had removed all the shims but when the blast cabinet was opened there were 5 shims on the floor of the cabinet. The valve seats have not been ground so my logic was the springs had been shimmed in the factory to a datum so I should be able to restore the datum using all the shims I have. They are now (I believe) back in spec. Long story but you offered help so I thought you deserved the full picture. Cheers Don Valve spring preload 1 i
 

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kiwi dave said:
To address the original question.

I replaced my springs (plus camshaft and followers) on a couple of 2002 EV Touring bikes. There was a special tool supplied which provided a reference point for measuring. You could possibly rig one up.

From the instructions:-

Using a gauge, measure the distance between the cylinder head and the reference point. Take note of the reading "A". (for example A = 89.2 mm).

Measure the distance between the valve stem end and the reference point. Take note of the reading "B". (for example B = 45.5 mm)

Calculate A - B - 43.2 = New shim to be fitted under the spring. Using the supplied shims, you should use a combination until the the value determined above exceeds the value calculated.

I could see you some scans of the pages involved if you provide me with an email address.

However, the heads on the Vintage may not be the same, as they were fitted with Breva 1100 versions I recall.

The real problem with the EV Touring was the valve springs originally fitted were way above specification (i.e. too strong) which lead to premature wear of the cams and followers. It took Moto Guzzi some considerable time to sort this out, and offered other fixes before deciding on the final solution. The cam also had a different profile with a ramp introduced to reduce the impact.

I owned three EV Tourings, I did two, the local shop did the first one as it was purchased from them. (They didn't do a thorough job IMHO). The other two I purchased from Moto International, and it was them that sent me the kit and instructions.

Hope this helps.
Click to expand...
 
Thanks for your input Dave. I don't fully understand your instructions without a diagram but no probs as I found the data and have shimmed my springs. See my reply if it interests you. Cheers Don
 
kiwi dave said:
It looks like you have a workshop manual for the Vintage. I've never seen one before.
Click to expand...
No, I spent ages cross referencing valves and springs part numbers until I found similar parts to the Vintage then looked for the appropriate manual and then checked my spring length with no shims fitted to see what sort of datum I was looking for, a bit of a circuitous route but I think I've got there.
 
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