| Author | Message | ||
     Not_purple_s2 |
After 20yrs of using the 1200 Sportster motor why has Buell never offered a 6spd trans. I know there Baker makes a 6spd but it's only for the tubers. I was a little disappointed that the XB's still don't have a 6spd, at least for the XB12R. Hell, if the new XB12R had an extra gear I'd be torn between it and the new 1125R. Personally my dream Buell would be the '08 white/blue 12R except with a 3.125" stroke & 3.875" bore (1208cc) and a 6spd trans. I figure that combination would yield a slight increase in power over the 12, a little less torque, and higher revs for a wider power band. Add to that an extra gear to keep up with the imports on the straights. Am I the only one who had these thoughts? The only real problem I see is that the large bore could cause reliability problems but it's way below the size of the XBRR. | ||
| Anonymous |
"The only real problem I see is that the large bore could cause reliability problems but it's way below the size of the XBRR." The 4.04 inch bore in an XBRR causes no reliability problems. The power-producing part of the XBRR is proving very reliable after a few improvements were made over the last year and a half. What is high maintenance is the driveline, particularly the primary drive and clutch. | ||
| Hughlysses |
Anony, Was the single-row primary chain that was tried on the early bikes abandoned, or is that still in development? | ||
| Not_purple_s2 |
Anony, I figured as much. I think my view of reliability comes from the retrofitting of the large bores to the current production cases. I assume that the XBRR had special casings that were designed with 4.04" bores in mind. It seems that the new XB's have more in common with the XBRR (oiling system, larger crank pin). Are they better prepared for large bores? If so what's stopping the production of a short stroke 12? I think that this would be ideal for the XB12R. (The long stroke suits the hooligan attitude of the S models) And what is keeping Buell from producing a 6spd for the thunderstorm motor? Is it reliability? Does Baker own the patent on XL based 6spds? From what I hear the new helical gear trans is great but a 6th gear seems like a logical improvement. | ||
| Diablobrian |
IIRC the issue with the 6 speed transmission from the factory is getting past the EPA/DOT sound emissions testing. | ||
| Steve_mackay |
Brian has it right. I was in standing next to Erik when he said this. | ||
| Not_purple_s2 |
Thanks for clearing that up. A 6spd is too noisy? I wouldn't have guessed that. | ||
| Buellinachinashop |
I was told by an HD engineer that the new 6th gear (not the 1125's) is pretty much useless until you get over 75. If that would hold true for Buell, no thanks, I'll stick with 5. | ||
| Jackbequick |
Adding a 6th speed is not necessarily a quick and simple way to increase the speed of the bike in top gear. It may only spread the ratios out so that the steps between each gear are smaller. In an engine with a narrower power band, the smaller steps are a good thing. In an engine with a wide power band, smaller steps are less useful and, if you are spending more time shifting gears, may be of little value. The major difference is whether or not you have a transmission that is direct drive (1:1) in top gear or a transmission that is an overdrive (1:<1) in top gear. The newer H-D six speeds are overdrive transmissions. They have a .86 final drive ratio (1:.86 as opposed to 1:1) in 6th gear that and drops the engine speed about 500 RPM for a more fuel efficient cruising speed. If I remember right, at 80 MPH the RPM drops from 3,600 to 3,100. That is a useful and realistic RPM for a typically loaded H-D cruiser or bagger. It is sort of off topic or non-relevant to the 1125R, but the H-D six speeds also had or are having some issues with noise in 5th gear. I've read that the noise issue arises from the fact 2-3-4-6 are helical gears and 1-5 are spur gears. Spur gears make more noise at higher speeds and that is what is happening in 5th. If spurs gears are engaged, but coasting under no load, they don't make much noise. The noise issues probably relate to using or not using the layshaft gearing in top gear. If you want overdrive, you have to use the layshaft gearing. If you want quiet, the way to go is to lock the input and output shafts together and use direct drive. But direct drive cannot overdrive. The earlier 5 speeds used in the Buell XL engines are lay shaft type transmissions that use direct drive (1:1 ratio) in 5th gear. The input shaft from the clutch is locked to the output shaft by splines and dogs, and the layshaft and all the other gears are coasting unloaded at that point. And that makes them quieter. The noise issue that deters adding a overdrive 6th speed to the XL transmission probably arises from the fact that it would have to drive through the layshaft (not direct) and that brings additional gearing and noise into play. I think there are some further factors here, such as exactly which gears and/or engine speeds must be used in testing for meeting the EPA noise level requirements. As I understand the 1125R transmission, it also uses a lay shaft (like the older transmissions described above). Correction! 1125R does not have a layshaft transmission - see Anonymous input below And I also read in one of the threads here that the 1125R has a .96 (not 1:1) drive ratio in 6th gear. If that is correct, the 1125R already has an overdrive transmission. But I'm wondering if the reported .96 ratio is right as that would not be of much benefit. It would seem that if the 1125R was going to have an overdrive transmission, the overdrive ratio would be a lower number to provide higher speed at a given RPM (or a lower RPM at a given speed) because it is an engine with a good power band. Jack (Message edited by jackbequick on July 12, 2007) | ||
| Not_purple_s2 |
Wow, thanks for the info Jack. Notice that the 5th gear ratio on the 1125 is 1.04 so a 6th gear of 1.00 wouldn't make much sense. The .96 sixth should put you around 4-4,500rpm at highway speed. | ||
| Anonymous |
The 1125R has a countershaft style transmission, where power flows through the input shaft and out the countershaft, passing through a single gear pair in every gear. Harley manufactured engines use layshaft transmissions, with direct drive in one gear, generally 5th, and power passing through 2 gear pairs in all other gears. | ||
| Jackbequick |
Anony, Thanks for the details. That all makes a lot more sense now. I was looking at the transmission cutaway on the minisite and just couldn't figure it out. Now I won't have to buy an 1125R and take it apart to see what is in it. :>) Jack (Message edited by jackbequick on July 13, 2007) | ||
| Just_ziptab |
The "72 Buell" has spur(straight cut) gears. It's gotta make a song of it's own, but doesn't rob power from side thrust compared to the helical gears in the 5 speed XB trannys........... |
