| Author | Message | ||
     Daman |
Hey Guys, I have been reading this website for a while now and find it very useful. I do a lot of highway driving between school and work. Its 40 miles each way. I cruise at about 85mph, which is 4200rpms. I was wondering if there is something that I could do to lower the cruising rpm for instance a 6-speed kit or euro gearing. Does someone offer these? Thanks in advance. | ||
| Trojan |
The US and Euro gearing on the XB12 are the same, it was only the old 'tubers' that were different. As far as I am aware there is no 6 speed box available for the XB series. Andrews apparently make a close ratio gear cluster for the XB though, but I don't know what the ratios are. | ||
| Dj_rider |
maybe, hopefully we will see a 6 gear transmission!!!!!!!!!!! | ||
| Fullpower |
i have given a very thorough consideration to the gearing on the XB12. in the beginning of my investigation, i thought that lowering the primary gearing 11% with the xb9 primary chain and engine sprocket would be fun, but after further reflection, i can see the limit of acceleration is the 52 inch wheelbase, and propensity to wheelie. so for low gear, the stock first gear is just about as low as one would want. in regard to higher gearing, the stock power to frontal area(drag) ratio is such that one can just barely, under ideal conditions, flat smooth pavement, a small well tucked in rider, perhaps a whisper of tailwind, and some good dry dense ambient air and a good long run scratch the rev limiter in top gear. so any higher gear ratio would cut down on top speed, ie sufficient thrust to drag ratio would decline, and top speed would be lowered with even a tiny increase in gearing. as far as cruising at 85 miles per hour: that is not an unreasonable speed to turn for the hour and a half that your fuel supply will last. the xb is not working real hard at a higher cruise speed like that. the rpm's should not scare you, the motor is pretty smooth at 4k. so my current analysis is that the factory engineers did a pretty good job of matching the overall drive ratios to the possible operating parameters of the machine. | ||
| Sshbsn |
Guilty as I feel about it at times, I frequently hit the rev limiter in fifth gear. I think it would definitely pull a taller gear, but then you'd have to downshift to pass at freeway speeds probably. BTW I'm, 5'10" and 170 lbs. Maybe I'm just good at tucking in... | ||
| Wyckedflesh |
I think giving up some top speed and a little bit of acceleration for a cruise of 3500-3750 RPM 85mph would be nice. I think the MPG might actually pop up to close to 60mpg if there was a pulley setup to give me that kind of RPM. | ||
| Xbolt12 |
Other bikes with around the same hp (Ducati 748 for example) pull higher top speeds which tells me the xb12r is capable of a somewhat higher top speed with the right gearing. Problem is you would have to go to the chain conversion to do it. xbolt12 | ||
| Wyckedflesh |
however a 748 has a 6speed which will always out top speed a like powered 5 speed. | ||
| Trevor |
hey guys, I have been lurking around this site for a while now and this is my first posting. I will be road racing my new '05 XB9 next season. I have been researching Buell performance mods for the past month and I am interested in the twistgear helical fifth gear main. It boasts a 30mph top speed increase at the rev limiter, with near stock ratios for 1-4 and a 1:1 fifth. Fitment is for tube frame models with the trap door but I think it will fit xb's by splitting the cases. Their website is twistgear.net. Any feedback on this subject or building a competitive Buell road-racer would be appreciated. thanks. | ||
| Wyckedflesh |
Don't be certain that gears are interchangeable between XB's and Tubers unless they have a matching partnumber stock. That trapdoor assembly allows for wider/thicker gear faces so I would be absolutely certain before making that decision. | ||
| Trevor |
sportsters (since 94) and buells (since 96) have used the same fifth gear mainshaft (up to and including all 2005 models) part number 35034-94. I have a call in to Johnson Engineering, the company that manufactures the twistgear main, but haven't heard back yet. I also talked to the techs at my service department and they seem to think it can be done by splitting the cases. I think buell did away with the trap door trans. for among other things strength and lighter weight, not necessarily to reinvent the sportster transmission. The idea of changing the fifth gear main is basically keeping first through fourth the same but stretching the gap on fifth a bit. We are killing the leader bikes in the corners and on braking, but we top out before the first quarter mile at 133 mph, they blow by us at 180 and we catch them again on braking and corner speed. Chain drives are messy and expensive to install and require a real art to get the right combination of sprockets. I think this might be the way to go to gain that extra top speed as long as I have the horsepower to pull the gap at fifth. | ||
| Trevor |
I just got off the phone with Johnson Eng. and the gear set will fit the XB's. There is a guy @ A Florida dealership that raced with it last season. I will try and contact him and share what I learn from him. It retails for $570.00 for the complete kit. He recommended using a 29/55 final drive to achieve 160mph top speed | ||
| Aaron |
What the Johnson thing does is makes 1st through 4th shorter. 5th remains 1:1. So you end up with a big rpm drop when you shift from 4th to 5th. They recommend a taller final drive because that'll put 1st through 4th back about where they were, but 5th will be taller. As far as going 160 is concerned, gearing for it is the easy part. The hard part is making enough power to get there. Horsepower required goes up as the cube of the speed increase. For example, if you have enough power to support say 140mph on your bike, to go 160 with no aerodynamic changes would take almost 50% more power. | ||
| Trevor |
I'm thinking about branch heads, a 1050cc big bore kit, 600+ lift on the cams, a F.A.S.T. induction system from hillbilly motors and the Useforce race kit (exhaust header and race module only) along with a sharkskinz racing body. I think this will more than compensate for any horsepower loss shifting to fifth. Any idea on which cams I should run with? | ||
| Trevor |
128 horsepower, that's impressive. Does Nallin make a 100+ horsepower 1050 kit for XB's? I want to stay in the 650 class for now because I can race more and we are really competitive. 1050cc is as big as I can go with air cooled twin. | ||
| Trevor |
oops 124.8 hp, still very impressive. |
