Valve shims

AndyW said:
Apologies, I guess I must've been imagining things again: I wish the trip through to Bellingen (and back again) a few years ago with *1588* in the back of a ute due to closed up clearances after only 1000km had been imaginary too along with Red's readjustment of shim clearances both ways to Cosi's place (and that's not so far from Brissy as Townsville is) the following year. *1173* barely made it from Townsville to Proserpine and back (700km round trip) before displaying the now familiar symptoms of diminishing valve clearance. In much of QLD and also South/Central Australia generally it's hard to 'cane' a Lav without losing your licence due to the wide open nature of the roads. EG it's possible to cruise along at 110-130km from one fill up to the next without even changing gear... I don't think this really does the older valve seats (mb valves too) any good: word on the streets of Southern Victoria seems to echo this sentiment..
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If the bikes were all as bad as you say yours are then no one would be able to use them. I'm not lying about my old 3C but maybe it's the heat in Australia that does for the pre oil cooler bikes?
 
sfcpiet said:
If the valve seats in the head skull remain untouched, clearances will stay stable for a very long time.  Re-cut seats will recess quickly, this slows down/stops once the seat surface re-hardens a bit.  Wider seats will not recess as quickly as narrow ones, but are not as good flow-wise.

When guides are replaced, seats generally need re-cutting.  Good time to decide which way to go.  Shim sizes are usually in the lower range by now, valve seat inserts restore these to as-new with the possibility to optimally configure the seat angles.  Shorter service valves with re-cut wide seats restore some shim size but with sub-optimal flow characteristics.

piet
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Hi Piet!

thank you for your input!

Attached a photo of my actual shims and clearances.

I decided to re-face the valve seat and valves to assure a good compression. Grinding them with valve grinding paste didn't work as good as I expected. When pulling the valve with two fingers as I was taught fuel goes slowly through them, but with springs mounted is quite sealed, just sweats a bit of fuel after 5/10 minutes.

My rectifier workshop told me: "just rectify them, quick and good result. Paste grinding is from the past days."

As I am about to order a set of electronic ignition to Red, I asked his opinion and said that he doesn't recommend me to re face the seats as my shims are already in the lower range, and that would mean to have shims about 1.70 thickness which is too thin. (if I understood properly) His proposal is to install 39.5 mm inlet valves instead of 38 and 35.5 exhaust valves instead of 35, so that they seat a bit higher when the seats are dressed, so I can go back to thicker shims and new dressed seats to assure a good sealing.

Another option is to leave all as it is, just grind them old school method, so I don't loose any clearances or veery little, hoping that the sealing is good enough.

Or as Piet says, new standard valves and make new valve seat inserts....???

Difficult decisions...

Miguel

IMG_6798.JPG

 
pf1 said:
If the bikes were all as bad as you say yours are then no one would be able to use them. I'm not lying about my old 3C but maybe it's the heat in Australia that does for the pre oil cooler bikes?
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we have winters too over here so maybe it's constant throttle they don't like. Pretty sure most folk over here have swapped out their early for later heads in order make bettter/more use of the older models.
 
michipons said:
Now I was thinking... If I make new valve seat inserts... I can put new guides and then I have a lead free engine???

Miguel
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I think Slaters used to be able to organise that: not sure if Richard still offers that service ???
 
You aren't going to preserve valve seats by going vroom-vroom instead of vroom.

You aren't going to rejuvenate a 50 year old alloy casting with wishful thinking.

Paul
 
Hi Miguel
              Commercial valve grinding paste usually has coarse paste at one end of the tin and fine at the other and is cheap rubbish. Search for industrial lapping paste about 600 grit which is far superior. You're looking for a pale grey finish on valve and seat. Cleanliness is very important, use a toilet roll to wipe valve and seat spotless. The valves will bed themselves in on their own in a couple of miles. Your head is not that bad to spend a fortune on it, it's got miles left in it yet.

Kind Regards  Bob
 
yes, it would work anyway if I leave all as it is, but there is not much left as new shims will be already below 2 mm... As I am rebuilding the engine totally, including crank rebuild with Keith I thought I go to full, so I have engine for many many years.

And what about the satisfaction of doing a nice good job?? this doesn't count?! come on guys!! I already have a wife!! I need you to tell me.... yeah!! go for it!! :LOL: :LOL: :LOL:

 
The problem with messed up cylinder heads and unleaded conversions goes back years. If you want the head doing send it to Piet or Keith but it doesn't need refurbishing yet. As Bobsol said it won't need attention for some time to come. Many heads have in the past been worked on and rendered scrap as a result.
 
pf1 said:
The problem with messed up cylinder heads and unleaded conversions goes back years. If you want the head doing send it to Piet or Keith but it doesn't need refurbishing yet. As Bobsol said it won't need attention for some time to come. Many heads have in the past been worked on and rendered scrap as a result.
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Ok, I will be cautios, for the time I will not touch it, but red will send me all so I can go both ways. My engineering workshop is quite good, they said that doing that to my cylinder head is a minor job for them, they said, result will be perfect without problems. They said they do that many times per day. However the crank is going to Keith as they said that they could have problems with spares and the need to make specific tools for that crank would be too expensive, alike the head.

The thing is that now it is easy, all the bike is apart, I would hate to disarm everything again a couple of years after the restoration...
 
Paul Marx said:
Do not give a triple cylinder head to somebody not used to working on them.

Paul
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Ditto,
Sent my head to a guy who was the MC engineer expert in Perth. Guides, reface valves, ceramic coating, Came back soft in the area of the r/h exhaust area of the cam bearing.
The ex. cam was binding after torquing down the cam blocks. A straight edge across the top face showed that area was no longer flat. Shimmed the block up so the cam ran freely,
100 kays later the cam was binding again. Sent to Red who faced the top surface and supplied taller cam blocks but that area just collapse again resulting in a binding cam again.
Solution, replacement head. That original head cost me in excess of 2000 oz$$$ and now it's a door stop.
Prior to the head refurb it had gone 45000 kays without needing a shim change
The point being, don't trust anyone unless it's Red, Piet or Keith.
 
motoddrob said:
Ditto,
Sent my head to a guy who was the MC engineer expert in Perth. Guides, reface valves, ceramic coating, Came back soft in the area of the r/h exhaust area of the cam bearing.
The ex. cam was binding after torquing down the cam blocks. A straight edge across the top face showed that area was no longer flat. Shimmed the block up so the cam ran freely,
100 kays later the cam was binding again. Sent to Red who faced the top surface and supplied taller cam blocks but that area just collapse again resulting in a binding cam again.
Solution, replacement head. That original head cost me in excess of 2000 oz$$$ and now it's a door stop.
Prior to the head refurb it had gone 45000 kays without needing a shim change
The point being, don't trust anyone unless it's Red, Piet or Keith.
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Or Gijs no doubt.
And what about Ricardo, Giuseppe, Augusto?

Paul
 
michipons said:
Hi!

How do you measure the valves shims? all my Palmer (micrometer) are too thick to go in them! I thought about making a thinner rod/bar with an exact meassure and then extract it from the total measurement, but may be you have a better and more accurate solution? where to find a micrometer slim enough?

Are those shims specific for Laverda, or can I find them somewhere else? They are expensive enough for not having private stock of a few for each measure, but making an order to usual Laverda dealers for just a couple of shims... is a bit tedious.

Miguel
Have a nice weekend!
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I check mine with a 5mm diameter roller taken out of an old taper roller bearing I had lying on the shelf in my workshop. Just measure the length of the roller and go from there. You do need to be careful and rub the ends of the roller on a bit of wet/dry paper for a while to make sure they?re dead flat but that?s not a big deal.
 
You need a micrometer with a measuring pin diameter of less than 7mm so it'll fit inside the shim cup. I actually have one but it's ancient (inherited it from my father). Seems most micrometers have larger pin nowadays. The pin diameter is not something that manufacturers normally specify, so if buying on-line, you'd need to ask. If buying in person from a shop, it's easy enough to check it yourself if you take a micrometer with you ?  :)
 
Regarding micrometer, I found one from V?gel with a pin of 6?8mm, fits perfectly, it is the ?cheap? micrometer version from V?gel, the super precise and expensive has 8?5mm, but not necessary for meassuring shims.

Well, finally after talking with Red and Keith, and after reading your posts, I couldn?t risk the moment when you would tell me: ?I told you?!🤣🤣 So I have finally decided to send my cylinder head to Keith together with the crank. He will do a total rebuild, no experiments, safe is safe. However someday I would like to do it locally, maybe when there is not so much to loose...

Miguel
 
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