Here's a topic for those whose grey matter tends to get caught up in these sorts of thought threads............
I've owned a few Guzzis in my time and have owned the breva 850 for a couple of months now.
First off, great bike! 'Sexy' is not doing it justice, handles well, sounds great and is plenty powerful-for me, anyway.
But the way it makes its power is not what I'd hoped for, I have to say. It almost needs to be ridden like a 2-stroke before those 70 horses are available i.e. 5,000-7500 rpm. In fact it occurs to me that in real world riding the breva 750 probably delivers the same hp i.e. between 2000-4500rpm.
I suspect that the engine has been tuned to provide impressive hp numbers rather than rideability, hence the almost identical rpm numbers for torque and hp (7000 & 7500).
I think that what has happened is this; MG use essentially the same engine/chassis for the various incarnations of the big block norge/breva and, even tho' the 850 has a shorter stroke it still uses the same cycle and engine parts as its brevona. Hence we find the same cylinder head, valve sizes/ throttle bore on the 850/1100 and 1200 machines. This means that they all share 46mm valves and 45mm throttles. Inevitably, I think that this means that the 850 valve/throttle bore is a bit big for its displacement - hence the high torque peak. Interestingly, the 1100 and 1200 big blocks (with same cams, valves, throttles) have progressively lower rpm torque peaks but almost identical rpm HP peaks. I seem to remember that this was also true of smaller BMW twins such as the 650 and 850 twins (using the same heads as the 1000 engines) back in the 70's, 80's.
I'm over the squiddley side of riding the back roads and really get off on the long-legged performance of my previous Guzzis however, I also really like this 850 Breva. So, the thoughts that I am having are to perhaps squeeze down the intake ports (just before the valve guide) to perhaps 85% of the current bore in the hope of lowering the torque peak to perhaps 5500/6000, along with changing the intake/exhaust lengths to match this rpm level.
Any thoughts? Pete Roper? Anyone?
Or should I just go out and get an 850T?
I've owned a few Guzzis in my time and have owned the breva 850 for a couple of months now.
First off, great bike! 'Sexy' is not doing it justice, handles well, sounds great and is plenty powerful-for me, anyway.
But the way it makes its power is not what I'd hoped for, I have to say. It almost needs to be ridden like a 2-stroke before those 70 horses are available i.e. 5,000-7500 rpm. In fact it occurs to me that in real world riding the breva 750 probably delivers the same hp i.e. between 2000-4500rpm.
I suspect that the engine has been tuned to provide impressive hp numbers rather than rideability, hence the almost identical rpm numbers for torque and hp (7000 & 7500).
I think that what has happened is this; MG use essentially the same engine/chassis for the various incarnations of the big block norge/breva and, even tho' the 850 has a shorter stroke it still uses the same cycle and engine parts as its brevona. Hence we find the same cylinder head, valve sizes/ throttle bore on the 850/1100 and 1200 machines. This means that they all share 46mm valves and 45mm throttles. Inevitably, I think that this means that the 850 valve/throttle bore is a bit big for its displacement - hence the high torque peak. Interestingly, the 1100 and 1200 big blocks (with same cams, valves, throttles) have progressively lower rpm torque peaks but almost identical rpm HP peaks. I seem to remember that this was also true of smaller BMW twins such as the 650 and 850 twins (using the same heads as the 1000 engines) back in the 70's, 80's.
I'm over the squiddley side of riding the back roads and really get off on the long-legged performance of my previous Guzzis however, I also really like this 850 Breva. So, the thoughts that I am having are to perhaps squeeze down the intake ports (just before the valve guide) to perhaps 85% of the current bore in the hope of lowering the torque peak to perhaps 5500/6000, along with changing the intake/exhaust lengths to match this rpm level.
Any thoughts? Pete Roper? Anyone?
Or should I just go out and get an 850T?