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Post by kevinbrixhamdivvy on Jun 7, 2009 17:51:01 GMT
I think the divvy 900 is under geared running at around 5000 revs at 70 mph. Has any tried or know a way to raise the gearing? I think this would improve the fuel consumption when cruising and actually make the bike feel more relaxed at motorway speeds. Any ideas?
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Post by CD on Jun 8, 2009 14:12:10 GMT
It might not help the fuel consumption - the valve timing will have too much overlap at low speeds so any gains in friction losses will be off-set by higher pumping losses. I find mine is quite happy at that speed. Its also just above the vibration range so I'd not want it spinning much slower.
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Post by bobh on Jun 12, 2009 16:20:52 GMT
Just about all the vehicles I've ever owned have had a happy cruising speed somewhere between half and three-quarters of the way up to the red line, which coincidentally happens to be where the peak of the torque curve is. The D9 is no exception, so unless you regularly want to cruise at over 90 I'd leave the gearing alone.
But if you really want to go ahead, have a look at the transmission from the 1100 Bulldog, as I imagine that must rev significantly lower than the Divvy.
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Post by Ol' Greasy Dave on Jun 14, 2009 10:18:57 GMT
as CD said - just above the vibration range & around 60mpg - why change perfection?
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Post by mikestrong on Jul 5, 2009 14:53:37 GMT
Got my D9 with 14k on the clock 1997 model. When I got it 5,000rpm pulled 70 mph in 5th & produced around 50mpg
In just over a year I've put on another 7k miles but is hitting 70 at 4,500 rpm now.
To get over that 5k vibe area have to bimble along at a different speed ;D
Probably means just starting to get run in.
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