Givi A660 Screen Review
Initial Review
This is an interim Givi A660 Review
The screen is on long term test to see what it's like day in day out in all weathers (rain, snow, hot, cold, near gale force wind).
Check back here for updates (currently its June 2008 and no sign of hot weather in the UK yet).
The figures in red (below) are provisional and will be confirmed after long term testing.
Also see Motorcycle Universal Screen Review and Givi A601 Review
A picture with its dimensions are in the link below
http://www.givi.co.uk/caschi_borse_bauli_accessori.asp?CO_ID=12586&lang=en
Design
The screen is well designed and it performs very well (highly recommended).
It's so good in every way I assume its been designed in a wind tunnel or with very advanced computer aided design.
The wind noise (turbulence) off the top of the screen is very good.
The top of the screen is angled upwards to stop the wind being fired straight at rider's helmet.
The screen is very stable in strong winds in any direction (makes bike stable).
The rider is protected from the wind very well vertically and horizontally and yet still allows fresh slow low turbulence air to reach the rider's helmet.
Review
This screen is very quiet. It's actually much more quiet than with no screen.
This review was done on a Honda CG125 motorcycle 2004 to 2008 version (125cc 4 stroke with less than 11hp).
I was able to mount the screen 8 cm above the headlight to get the ideal height of just below eye level when riding (that's the maximum height possible on that bike).
The screen actually deflects the wind so it hits above eye level.
I could also get the screen very close to the instrument panel to reduce the gap between rider and screen(rider is a long way back due to very upright riding position)
Without a screen the bikes normal top speed would be around the 65 mph mark.
But that could drop to as low as 50 mph against a very strong headwind.
Please note, when you go past peak engine revs the power drops off dramatically since its a push rod engine,
so it does not matter if its a 60 mph back wind and down hill, when you hit peak engine revs the power drops off and stops you going much faster.
So when I say top speed increases by so much, that's of course until you hit peak engine revs,
so top speed increases by so much is only when you have a head wind.
The Good
Top speed with a normal coat was 10 to 15 mph faster than without a screen.
Top speed with a leather coat was 5 to 7.5 mph faster than without a screen.
Even with a leather coat on and my chin on the petrol tank without a screen,
the screen gave at least 3 mph more speed and no need to put my chin on the tank.
With the screen on there was no change in top speed if I lowered my body since my body was already protected by the screen.
With the screen on, leather coat and done all the things in the Improving Performance page,
the bike no longer really benefits from sitting behind a 56 mph lorry to increase the top speed against a very strong head wind.
The screen actually gave more of a speed increase than no screen and sitting behind a lorry (within your braking distance) in very strong head wind.
So at last against a very strong head wind (you can only manage 60 mph), you can easily overtake a lorry while its accelerating,
or against a strong head wind overtake the 56 mph lorry with the bike managing 65 mph.
And after you have overtaken the lorry, you will be able to at least manage and keep up 60 mph even with a strong head wind and up hill.
The speeds above are for someone around 5 ft 10 inch tall and around 11 stone (70 kg).
Since the bike is small and underpowered, if you are significantly larger or heavier, you will be slower.
Even with leather coat on, fuel consumption improved by 5% even though bike was travelling faster,
so after several thousand miles the screen would pay for itself.
The bike is much more stable in near gale force side winds.
Going round corners was more stable and faster due to less wind resistance,
which creates in effect more power from the engine to pull you round the corner and the wind can not push you in another direction as much.
The Bad
Its pretty hard to find anything bad with this screen unless its to tall for you (most riders do not like having to look through a screen).
Since the screen reduces the wind resistance so much the brakes have to work harder and if you increase speed engine revs are higher.
The increase in speed could tempt you to cruise the bike above 65 mph,
I advise against going past this speed for a long time since it will increase engine wear substantially.
So go above 65 mph for overtaking traffic only.
What causes the engine wear is not only the extra high engine revs, its also the longer your at those engine revs the more heat build up you get.
I personally would never go to 70 mph since the engine revs are far to high,
going past this speed even for a quick test is crazy unless you do not care about engine life (to far above 70 mph could cause engine damage).
I personally cruise on normal roads at 60 mph (to protect engine),
on dual carriage ways where the speed limit is 70 mph I often cruise at 63 mph if traffic is fast moving or even 65 mph for short periods.
I limit my overtaking speed to 66 mph.
With prolonged high engine speeds, the oil you use and changing it earlier than normal is critical, see Which Oil quality to use in the Servicing page.
With the best oil, if the majority of the mileage was done at 60 mph with a substantial amount above 60 mph I would change the oil every 1500 to 1750 miles.
All of the above speeds are based on the 5 speed gearbox and using 5th gear, a 4 speed gearbox could easily be different.
The 5 speed bike was the Front Disc Brake model, to see the RPM of the engine have a look at the MPH to RPM page.
For all other models of Honda CG125 look at the speedometer, look carefully and it should show you the maximum advised speed in every gear.