LAVERDAMANIA

Cylinder heads:

RESTORATION

Click here

VALVES CLEARANCES


- 750:
Inlet: 0.15mm, Exhaust: 0.25mm
(S and SF); 0.20mm (650, GT, American Eagle)

- 1000/1200:
Go to the special printable page: Click here

VALVES

Model
In
Ex
IN ANGLE
EX ANGLE
650
38
34
32°30
37°30
750 GT, S et SF0
38
34
32°30
37°30
750 SF1, SF2, SF3
41,5
35,5
32°30
37°30
750 SFC 1971
41,5 (tige 8mm)
35,5 (tige 8mm)
32°30
37°30
750 SFC 1974
41,5 (tige 7mm)
35,5 (tige 7mm)
32°30
37°30
750 SFC 1975/1976
41,5 (tige 7mm)
35,5 (tige 7mm)
33°
37°30
1000 3C, 3CL/1200
38
35
20°24
19°49
1000 Jota normes France/Suisse
38
35
20°24
19°49
1000 Jota/1000 RGS
39,5
35
20°24
19°49
RGS Corsa/1000 SFC
40,5
35
20°24
19°49

TORQUES


- 750:
- All 8 main nuts: 5 m/kg (36 ft/lbs)
- The 3 secondary nuts: 2.5 m/kg (18 ft/lbs)

- 1000/1200:
For some reason that I can't understand, some books indicate wrong torques...
Correct torques are:
- All 9mm nuts: 3.5 m/kg (25 ft/lbs)
- All 8mm nuts: 2.5 m/kg (18 ft/lbs)
- 7mm nuts: 2.0 m/kg (14 ft/lbs)

Tightening the nuts more than the torques above will strip the threads in the top crankcase! Never tighten the M9s nuts (shorts or longs) to 28 ft/lbs and more!

Warning: Some mechanics were/are not aware of the correct sense of the studs, resulting in studs fitted upside down. Once again, this mistake causes stripped threads in the crankcase!

WORKING ON CYLINDER HEADS


Restoring a cylinder head is an affair of specialist or at least a very good mechanic.
Some informations:

- To order parts:
It's necessary to get parts from a reknowned specialist, who knows exactly what you need and what you intend to do. Wolfgang Haerter is definitely one of them:
http://www.angelfire.com/biz/laverda/index.html

- To remove the valve guides:
A good way is to drill carefully almost all the guide material from the inside, without altering the alloy of the head. Then heat the head to 120 - 150°C in a oven and push the guide
outside.


- To fit the new guides:
The tightening of the guides in the head must be between 0.08mm and 0.11mm.
The guides are available in standard size, 1rst oversize and 2nd oversize. It is necessay to heat the head in a oven, about 120 - 150°C.
Check the bores. If they are not in perfect state (some mechanics removed them cold!), order oversized guides and machine them.

External diameter of the guides for 1000 and 1200:

Standard
1rst oversize
2nd oversize
Ext. diameter in mm
14,95
15,05
15,12

Clearances valves/guides for 1000 et 1200:

Admission
Echappement
Internal guides diameter
7,012 à 7,030 mm
7,035 à 7,055
Diameter of the valves pins
6,990 à 7,000
6,990 à 7,000
Normal clearance
0,012 à 0,040
0,035 à 0,065
Maximum clearance
+ de 0,200
+ de 0,250

Clearances valves/guides for 650/750:

Admission
Echappement
Internal guides diameter
8,012 à 8,030 mm
8,012 à 8,030
Diameter of the valves pins
8,00 à 8,010
8,00 à 8,010
Normal clearance
0,002 à 0,030
0,002 à 0,030
Maximum clearance
+ de 0,200
+ de 0,200

 

- Temporary repairs!:
For the most desperate cases, there are some solutions to repair valves and guides. See: http://www.newayts.com.au/guiderest.htm

- Valves seats:
The tightening of the seats in the head must be between 0,19 to 0,24mm. Then cut the seats on 3 steps, average of 1.5mm (maxi 1.5mm inlet, 2mm exhaust), then correct the concentricity with the guides.
Some tools?: http://www.newayts.com.au/seatguiderest.htm

- Where to find undersized shims for a triple engine?
The smallest Laverda shims are 1.85mm. However, in case of a recession problem, it could be useful to use thinner shims, one can use a minimum of circa 1.30mm
(be careful that the shim doesn't hit the valve collet).
It is possible to machine the shims but it is a hard and hasardous work. The best way is to order new shims at the correct size, a good adress in Australia: Precision Shims Australia: http://www.alphalink.com.au/~bullen/

WHAT'S ABOUT UNLEADED CONVERSIONS?

 

Unleaded conversions are totally unuseful on good state Laverda engines. They are even dangerous as many conversions are uncorrectly done, resulting in cracked cylinder heads,
loose valve seats, worn guides and valve stems. The problems often occur to the valve seats (fitted in a wrong way) and to the valve guides (the cast iron guides don't tolerate the stainless valves).

Lav engines run well with unleadead 95 to 99 octane ratio, no need to pay 1000 Euros or more to get an unleaded conversion...

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