Bigger Valves – 1150GS

[DrAlf]

Does anyone know of a source of information that details that valve sizes used by the various 1150 and 1200 oilheads? I’m looking to possibly increase the size of the valves on my trusty 1150 – any info would be greatly appreciated.

Thanks in advance

Adam

 

[Mouse]

According to the 1200GS technical manual:

Inlet valve seat, outside diameter: 38.617 mm
Outlet valve seat, outside diameter: 34.134 mm

 

[DrAlf]

Thanks Mouse. Not a great deal of info out there on 1150\1200 valve sizes. Still looking….

 

[Dusan]

yeah

And ya don't reply to ya old riding buddies,is it cause they can't keep up!!! B~)

 

[DrAlf]

PM sent now shut it Back on track - valve sizes anyone?

 

[Dribblers Dad]

1150 gs

Valve head Dia Inlet 34 mm, Stem Dia 4.966 mm, Valve head edge Thickness 1.00

Valve head Dia Exhaust 29 mm, Stem Dia 4.956, Valve head edge Thickness 0.9 mm

Both valve seat angles are 45 Degrees

Dont know about stem lengths


Cheers DD

 

[DrAlf]

Thanks for the info. What I really want to know is do any of the 11xx series oilheads feature bigger valves than the standard 1150GS? If so, is it worth fitting heads that feature bigger valves – what kind of performance increase can I expect and what else would need to be done to the bike – just a chip?

Please don’t tell me to go out and buy a sportsbike – I love my old GS but sometimes I feel it could do with just a little bit more go

Thanks in advance

 

[Dribblers Dad]

If you try here http://www.maxbmwmotorcycles.com/fiche/fiche.asp you can compare the various engine parts for the different models, I think the RT and RS use different pistons to increase the compression and a different cam profile to give more top end power, this may or may not be at a detriment to the mid range that the GS has, Dyno charts anyone? The inlet snorkels are different diameters and lengths on other bikes as well , you need to ask someone who has carried out this kind of work already and ask them the best starting point.

Cheers DD