2010 observation

[Deleted account 190920001]

Just been to the dealers to get my indicators looked at so had a good nose around the 2010 GSA they had. I noticed it has an exhaust valve (EXUP valve not the ones in the heads) now and I will put money on it that this is where the better torque curve comes from. Exhaust valves both improve drivability and silence the bike more at lower revs. A quick look at the silencer showed the exit was larger as well probably meaning it isn't restricted so much in the silencer either. The reduced restriction could possibly lead to an increase in overall power as well. I doubt the introduction of DOHC has very much to do with any power increase on the GS/GSA probably has a larger bearing on the HP2 sports though.

 

[GSband]

The new engine design with dohc allows :
- larger diameter valves
- increase in valve displacement

Other consequences of these valve changes :
- bigger airbox
- different air filter
- bigger air intake funnel
- larger diameter exhaust header
- larger diameter connection pipe

The dip in the torque curve is still there, it's just moved up to over 5000rpm (more or less). In day to day use, riders will not encounter this rpm zone.

 

[karlp]

The new engine design with dohc allows :
- larger diameter valves
- increase in valve displacement

Other consequences of these valve changes :
- bigger airbox
- different air filter
- bigger air intake funnel
- larger diameter exhaust header
- larger diameter connection pipe

The dip in the torque curve is still there, it's just moved up to over 5000rpm (more or less). In day to day use, riders will not encounter this rpm zone.

View attachment 144135

Interesting graphs.

The 2009 model has always been reported as having 105bhp output and the 2010 110bhp output
but according to the graphs displayed above

the 2009 has 110bhp and the 2010 has 113bhp

 

[Funners]

Interesting graphs.

The 2009 model has always been reported as having 105bhp output and the 2010 110bhp output
but according to the graphs displayed above

the 2009 has 110bhp and the 2010 has 113bhp

PS figures read slightly more than BHP....

 

[karlp]

PS figures read slightly more than BHP....

learn something new everyday

 

[Deleted account 190920001]

That's a nice quote from publicity blurb but there is no reason they couldn't have used larger valves in the old setup. I am not knocking what BM have done I just find it a bit pointless on the GS where they haven't went for the full potential like they have with the HP2. Personally I think the exhaust change on its own to give it more low end punch would have done the trick. That said despite some opinions on here I think moving over to shim adjustment on the valves are a move in the right direction. Sure they are harder to set but looking at every other bike that uses them the service interval is in the tens of thousands and they are much less likely to need adjusting in the first place.