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Jammin_joules
| | Posted on Saturday, January 03, 2009 - 12:39 am: | 
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So I guess a 12-spd harnessed to a Buell Blast will push that lil' sucker to 185mph then?
Naah, we know better.
More horsepower than torque allows gear ratios to develop top end speed.
Torque gives you acceleration, and dirt and hill climbing off road, you want acceleration.
A Uly is a balance between the two.
For me, a lower ratio first and second followed up with a 6th gear with final drive ratio identical to the current would suffice very nicely.
Sans that option readily available at reasonable price, it will be the 9 primary on Joules this winter. I ride off road far far more often than I hit 135mph.
~jammer |
Jphish
| | Posted on Saturday, January 03, 2009 - 09:58 am: |
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jammer - Your last sentence...Thats where I've landed. Did 125 once on my ST1300. After Doc's Bambi adventure (and my own) it's a good reminder "we don't own the road" - top end speed is less compelling for me anymore. I'm willing to make whatever 'sacrifice' the X9 conversion requires. More dirt capability (at least for the Uly - I'll follow in due course) is a fair trade off... at least for me. I've, in some cases, avoided some dirt routes due to the rigors of the beast off pavement. I plan on converting by end of Feb, before I head to southern Nevada - and some dusty stuff. Be interested in impressions of your 'conversion' experience. j |
Hangetsu
| | Posted on Saturday, January 03, 2009 - 11:43 am: |
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I'm not trying to start a fight here, but I need to clarify a couple of things.
First - Dave, I was in no way trying to indicate that having more gears would make a bike go faster. Every engine and bike will have it's ideal top gear ratio to produce its most favorable cruising speed and top end - given the engines HP, torque, power curve, etc. The next step is choosing the ratio that gives you the smoothest starts and, if off road riding is in the intended purpose of the bike, a ratio that allows the bike to deal with those demands. In the Uly's case, that would be quite a spread and at that point, without getting ridiculous, it's the number of gear's and the closeness of gear ratios in between that add to the bikes rideability by keeping the engine speed in or near the power band with each shift. This is why cars with any performance pretentions have gone from three to six speed automatic transmissions. There are even some six speed manual shift cars out there - all for the same reasons.
As far as top speed goes, nothing in my prior post said anything about wanting to maintaining a 135MPH top speed. There is no purpose for that an any vehicle on public roads. However, maintaining a comfortable engine speed while cruising on the open highway is important, to some. The average speed on most interstates these days is about 90mph. cruising much below that can be dangerous and keeping pace with that already puts the Uly's engine speed to the top of it's "comfortable" RPM range. The higher RPM's may not put more "stress" on the motor as pointed out by a couple of engineer types above, but it does put more wear & tear on the engine and consumes more fuel. And actually - running an engine constantly at or near peak horse power does put more stresses on an engine and will lead more quickly to a motors'early retirement.
Another fact that most don't consider it that running constantly at higher engine speeds also puts more stress on the rider. This may be a subjective thing, but in a conversation I has yesterday with a fellow Badwebber this topic came up and I had to agree. You log six hours on the slab buzzing that engine at 4500+ RMP and I think most of us would be a wreck at the end of the day.
Anyway, also as pointed out in a prior post, it really comes down to what you demand from your Uly. I know "Jammin" up there takes his Uly to some pretty gnarly places and the XB9 conversion makes total sense. I spoke to someone who does a lot of stop & go driving in traffic and I can see where this conversion will truly benefit him. For anyone else, unless on-demand wheelies are what you're all about, I personally can't see where the Uly's current gearing is deficient in any way.
But all if this is truly subjective, isn't it? |
Hughlysses
| | Posted on Saturday, January 03, 2009 - 12:20 pm: |
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It would be interesting to see how well the engine would work with a wider-ratio 5 speed. Something that would give the XB9 primary 1st gear ratio but the stock 5th gear ratio. Stock is:
Gear Ratios
1st 2.648
2nd 1.892
3rd 1.407
4th 1.166
5th 1.000
The bike would definitely tolerate a bigger "jump" between 4th and 5th, which would allow 1st through 4th to be lowered without killing the bike's performance. Of course, the $1000 question is if there are any off-the-shelf gears that could be used to accomplish the change. 1st through 4th on the Blast is a little lower, but not enough to be worth the effort (IF they would work). Anyone know if appropriate gears could be sourced from Sportsters or aftermarket?
My guess is the stock ratios are picked as much (if not more) for EPA noise compliance than they are for best performance. |
Rotorhead
| | Posted on Saturday, January 03, 2009 - 01:21 pm: |
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I'm in agreement that the engine RPM"s and the gearing for each engine has to match to have "Harmony" between them. Ask any HD guy who bought into the new 6 speed tranny's. To have a happy 6 speed they had to bump up the engine size to keep the same RPM range to push the 6th ring.
My father inlaw traded a 5 speed HD for a new 6 speed half way through a 7500 mile trip. The engine on the 6 speed would bog down 2 up where his 5 speed wouldn't. He loves the 6 speed on the flat interstae but nevers uses 6th other wise.
The 9 switch is where rider compromise has to come on the Uly.
Going out to get a fuel milage report I'll be back! 100 unpaved 100 paved. today tomorrow 200 superslab. |
Hangetsu
| | Posted on Saturday, January 03, 2009 - 01:26 pm: |
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That 6 speed HD (I really know nothing about it) may have a higher or even over driven 6th, which would account for the engine bogging. What we're talking about here is a lower first and leaving the top where it is. |
Tootal
| | Posted on Saturday, January 03, 2009 - 03:03 pm: |
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Nah - simply doesn't need it.
You'd end up rowing it between 3rd and 4th instead of leaving it in third and hammering though the twisties.
That's not what I would want. I only ask for a 6 speed where 2-6 are the same as 1-5 are now. First gear in the 6 speed would be lower than it is in the 5 speed. No other ratio's change. This would be like having your cake and eating it too. When off road or in slow traffic you have a first that will not require you to slip the clutch constantly. When your riding out in the open spaces, just start off in second gear as it would be the same as first gear is now. Simple. Everybody's happy! |
Danger_dave
| | Posted on Saturday, January 03, 2009 - 05:34 pm: |
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All good - just conversation.
I took the question: 'Are 6 speed gearboxes overkill on a 65+ horsepower ROAD motorcycle?'
to the general (not brand specific) bike groups I hang out in.
So far there is quite a solid majority for 'YES'.
(Message edited by danger_dave on January 03, 2009) |
Tootal
| | Posted on Sunday, January 04, 2009 - 06:32 pm: |
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I agree on a ROAD motorcycle, it's the off road/dirt road capability of the Uly that a lower first gear would be nice, hence the need for 6 speeds. I wouldn't want to change the other ratio's at all. After doing the XB9 primary swap I like the lower first but truthfully I would like it even lower but not enough to lower the overall gearing anymore. That's where the 6 speed would be nice. Everything's a compromise I guess. Maybe since HD bought MV Agusta/Cagiva they might have some old Ducati trannys laying around they could copy! |
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