Valves 40 mm, 42mm or 44mm diameter ?

[bernardofeio]

Hello

Since I’m buying new valves to my engine witch ones should I buy?

Valve Exhaust 40 mm, 30° ?
Valve intake 42mm diameter ?

The 44mm valves are for what engine?

thanks
bernardo feio

 

[Thunder]

Hello

Since I’m buying new valves to my engine witch ones should I buy?

Valve Exhaust 40 mm, 30° ?
Valve intake 42mm diameter ?

The 44mm valves are for what engine?

thanks
bernardo feio

Bernardo

Which engine do you have?

 

[bernardofeio]

R 100 gs from 1990

Are the 44 mm an upgrade?

thanks

 

[thornley]

R100Gs
inlet 42 mm
ex 40 mm

Haynes manual 1987 on

 

[(RIP) Proff]

44 will need new valve seats and a recut,,you don't wanna do that

 

[Thunder]

R 100 gs from 1990

Are the 44 mm an upgrade?

thanks

Not without changing the heads, sizes are as Thornley has posted.

 

[bernardofeio]

Since the cylinders and heads are off should I consider any simple upgrade?


-Increasing the compression? What benefits and disadvantages? Any tips about the procedure?
-Free flow heads? (does any one have pics of the before and after?
…
…


thanks

 

[(RIP) Proff]

Since the cylinders and heads are off should I consider any simple upgrade?


-Increasing the compression? What benefits and disadvantages? Any tips about the procedure?
-Free flow heads? (does any one have pics of the before and after?
…
…


thanks

Increasing the compression will make the bastards run very rough as 100 octane petrol is no longer easily obtainable.
Thats why lots of earlier Airheads have a Base gasket [lowers comp]

Polishing heads and ports,
if it makes you feel good, do it..
I wouldn't bother unless there is obvious rough patches