Used to be very good- Serdi valve seat/ guides , not many head engineering shops left now & Len is motorcycle based as opposed to a general engineer- reckon he’s as good as anyone to go to.
everyone for the advice which will be taken...Keith is a two hour drive away and I'll take the head to him....he's got a strong reputation and after re thinking it would be daft to go anywhere else...I might not need to yet it seems likely I might be pleasantly surprised when the engine is stripped Thanks
I know that, I'm guilty of thinking out of the box...time to implement the good advice I've had from you guys 
Both bikes have been run exclusively on Euro 95 octane (the 3C got a splash of 102 for the track days, just to be on the safe side) since it was introduced in the EU.
thank you
Wooow, I feel a little bit like 6 years old and first class in elementary school.There is a big "IF" hovering over stock Laverda valve seats.
IF they are old and worn, they may well stand up to un-leaded fuel without issue. IF they are freshly cut, they may suffer from rather drastic valve recession during the first 10-20000km.
The stock cast iron of the skull is too soft for use with lead-free, only after being hammered by the valve a couple of million times do they work-harden enough to withstand the pressure. Even those heads with factory inserts, late 3CL/Jota etc and 120°>, do not stand up to lead-free without issue. These too require require a long running time to completely settle and even then, seat/valve wear is more pronounced than with hardened inserts.
Valve seat inserts not only bring shim sizes back in line, they also restore valve/port geometry and flow, aiding in providing a crisp power supply. The seats not only position the valves better within the combustion chamber, they can be cut to further enhance flow. There's more to seat cutting than your run-of-the-mill "3 angle valve job". Simply re-cutting worn seats, grinding the valve faces and lapping them will position them too far within the combustion chamber to expect full potential from the engine, flow is simply hampered to the point that power suffers. Sure, the seats can be pocketed, but that in turn further increases chamber volume and reduces compression ratio, further hampering power.
In order to gain full potential from those hard-to-find C4 cams and those horridly loud and expensive Jota cans, you won't be doing yourself any favours just by grinding in the old valves... all show and no go.
I overhauled the head of my 3C back in 1991 or 92 with new valves and seat inserts. Since then, approx. 50000km including several track days later, the shims have gone from around 2.80mm to the 2.60mm region. In fact valve clearance has remained constant the last 25000km. The head on my RGS is still stock, as far as I can tell. I've ridden this bike over 75000km, I got it with 38000km on the odo. In my possesion, the head has never been off, the cases not been opened. The valve shims are now at 2.00-2.30mm and clearance requires slight adjustment from one check to the next. I have the engine on my overhaul schedule, it has started using a bit too much oil for my liking and I have a freshly overhauled CR head for it on the bench, together with a shiny set of 10:1 pistons.
The available valves with over-sized stems are a real boon imo, it simplifies head work and saves a lot of valuable metal from being unnecessarily removed. The only problem is that the old guides are also wear-hardened and cannot be simply reamed to size with convential HSS or HSS-E reamers, tungsten carbide reamers are necessary (good luck finding those in the required size and at an acceptable price!), or, better still, they are honed to size. Due to the very short length of the triple guides, it is almost impossible to replace them concentrically to the seat, despite using guided mandrels etc and the seat often requires a lot of cutting to get everything back in line, so it is invaluable to be able to re-use the old guides.
Cutting the counterbores and fitting inserts is also something that should not be entrusted to somebody that has no experience with these heads. The skull has varying thicknesses, it is all too easy to break through the skull and weaken it to the point that it may crack in use and allow the seat insert to loosen or fall out.
Bottom line, the Laverda triple heads require quite a lot of insight and thought to restore properly, otherwise the (always) expensive result will turn out mediocre at best. Get it right, the beast will (again) go like the clappers.
piet
My 1980 mirage which I’ve owned for 30 plus years has CR stamped on the front of the head, only noticed this the other day what does this signify ?. I had the head overhauled a few years ago with hardened valves by Keith when valve clearances ran out.There is a big "IF" hovering over stock Laverda valve seats.
IF they are old and worn, they may well stand up to un-leaded fuel without issue. IF they are freshly cut, they may suffer from rather drastic valve recession during the first 10-20000km.
The stock cast iron of the skull is too soft for use with lead-free, only after being hammered by the valve a couple of million times do they work-harden enough to withstand the pressure. Even those heads with factory inserts, late 3CL/Jota etc and 120°>, do not stand up to lead-free without issue. These too require require a long running time to completely settle and even then, seat/valve wear is more pronounced than with hardened inserts.
Valve seat inserts not only bring shim sizes back in line, they also restore valve/port geometry and flow, aiding in providing a crisp power supply. The seats not only position the valves better within the combustion chamber, they can be cut to further enhance flow. There's more to seat cutting than your run-of-the-mill "3 angle valve job". Simply re-cutting worn seats, grinding the valve faces and lapping them will position them too far within the combustion chamber to expect full potential from the engine, flow is simply hampered to the point that power suffers. Sure, the seats can be pocketed, but that in turn further increases chamber volume and reduces compression ratio, further hampering power.
In order to gain full potential from those hard-to-find C4 cams and those horridly loud and expensive Jota cans, you won't be doing yourself any favours just by grinding in the old valves... all show and no go.
I overhauled the head of my 3C back in 1991 or 92 with new valves and seat inserts. Since then, approx. 50000km including several track days later, the shims have gone from around 2.80mm to the 2.60mm region. In fact valve clearance has remained constant the last 25000km. The head on my RGS is still stock, as far as I can tell. I've ridden this bike over 75000km, I got it with 38000km on the odo. In my possesion, the head has never been off, the cases not been opened. The valve shims are now at 2.00-2.30mm and clearance requires slight adjustment from one check to the next. I have the engine on my overhaul schedule, it has started using a bit too much oil for my liking and I have a freshly overhauled CR head for it on the bench, together with a shiny set of 10:1 pistons.
The available valves with over-sized stems are a real boon imo, it simplifies head work and saves a lot of valuable metal from being unnecessarily removed. The only problem is that the old guides are also wear-hardened and cannot be simply reamed to size with convential HSS or HSS-E reamers, tungsten carbide reamers are necessary (good luck finding those in the required size and at an acceptable price!), or, better still, they are honed to size. Due to the very short length of the triple guides, it is almost impossible to replace them concentrically to the seat, despite using guided mandrels etc and the seat often requires a lot of cutting to get everything back in line, so it is invaluable to be able to re-use the old guides.
Cutting the counterbores and fitting inserts is also something that should not be entrusted to somebody that has no experience with these heads. The skull has varying thicknesses, it is all too easy to break through the skull and weaken it to the point that it may crack in use and allow the seat insert to loosen or fall out.
Bottom line, the Laverda triple heads require quite a lot of insight and thought to restore properly, otherwise the (always) expensive result will turn out mediocre at best. Get it right, the beast will (again) go like the clappers.
piet
CR adorns the heads as fitted to RGS Corsa and 1000 SFC. 40.5mm inlet, 34mm exhaust valves, slightly enlargened inlet ports. Coupled to 10:1 pistons results in a very healthy 95hp with stock intake and exhaust system.
The CR head was fitted to 120° engines only but will fit any other Laverda triple, just requires the correct cams.
