| Author | Message | ||
     Austinrider |
Can anybody confirm that changing an '03 XB9 to an '04 XB's drive train will reduce top end? I had the fortune of attending a track day today. I noticed that on the "Big" straight of Texas World Speedway I was topping out at 110 - 115 mph for a top speed. Now, I know Im a big guy at 6'1 240ish pounds, but I could swear that before I had the drive system changed out I was topping out 10-15 mph faster. I know I havent gained that much weight since I last rode TWS in October of last year. Do any of our more experienced/smarter than me types care to take a minute and enlighten me on this. I know I had plenty of straightaway left, and I would glance down, see the rpms were in the yellow and go to upshift and realize I was in 5th gear. Look at the speedo and see I was in the 110 to 115 range. Any input is greatly appreciated. Regards, Phil **Changed a typo edited by Austinrider on February 16, 2004 | ||
| Glitch |
By drive train, do you mean you went with the '04 belt upgrade? Belt, front, and rear pulley, ect... | ||
| Austinrider |
Yes, since the belts teeth go deeper, the belt is wider the pulleys, belts and belt guards had to be changed out. | ||
| Glitch |
I was under the impression that it wouldn't change any of the drive ratios. I could be wrong though (I know it's hard to believe but it's happened before)... | ||
| Skully |
Determine the number of teeth on both of the old pulleys as compared to the upgrade. If the ratio of driven/drive is the same, the upgrade should have no effect. Keith | ||
| Englishman119 |
I was under the inpression that the final drive ratio's were the same XB9/XB12 ? - Buell spec sheets. The primary ratio on the 12 was taller. Did you feel slower Phil ? Mark | ||
| Austinrider |
Slow aint the word Mark. I was topping out at 110 or so on the Front Straight. When I pulled the clutch in and tried shifting up it would not go. Usually, in most cases, this means Im in 5th gear. Thing is, all my research shows that 110 is the top speed for 4th gear and not 5th. Now, I know Im on the heavy side, but not that heavy. I have gotten the bike over 110 before (on the same straight a way coincidentally). But yes, I felt like I was much slower. Until I hit the turns  . I was much faster in the turns this time around at TWS. Mark, I wanted to thank you for being Marcus' guinea pig with the suspension. His knowledge about my bike (an the copious amounts of Locktite and torque applied to the bolts) was very helpful. We changed the oil, bushings and seals out (I should say he was up till 2am doing the work - I was sleeping in my tent). Any ideas? Why would it not let me shift into 5th gear if I was shifting at about 6500 rpm's or so. Im thinking maybe my foot was hitting something or I was not forcing it hard enought. At that speed I wasnt about to look down, I just rode the rest of the sraight out at that speed. | ||
| Fullpower |
DOES sound a lot like a 4th gear rev limit to me. | ||
| Fullpower |
another possibility is speedo sensor problem. | ||
| Austinrider |
After watching the 1 video I managed to shoot it is deffinetly not a speedo problem. I wish it was, would mean I was going alot faster than I thought I was. Still a good time, and really I probably would have shut it down around 120 or so just because coming off the enbankment scares the holy hell out of me and I found myself grandma'ing that turn most of the day. edited by Austinrider on February 17, 2004 | ||
| Wyckedflesh |
I was looking through my trusty owners manual and came across some interesting wording... (pg 14 table 6)(XB9/XB12) Engine 34 tooth/38 tooth clutch 57 tooth trans 27 tooth/29 tooth rear 65 tooth belt 128 tooth However when I looked in my service manual table 6-2 it says the trans uses a 27 tooth final. Now this is out of the Lighting owners and service manuals. My firebolt manual is not at hand and I don't have an owners manual for my firebolt. Just thought I would toss this up to add more confusion  | ||
| Austinrider |
Thanks wycked, but I suck at ratios. What exactly does it mean? | ||
| Wyckedflesh |
If you went from a 27 tooth to a 29 tooth it would account for the drop in top speed. | ||
| Blake |
Going from 27 to 29 teeth on tranny would increase theoretical top speed at redline by 7.4% while the indicated speed versus rpm would be unchanged and thus low by 7.4%. edited by blake on February 18, 2004 | ||
| Austinrider |
I will be giving it another shot at the track in March (at least I hope to). I'm going to have the 5k service done and change the fluids by then. Hopefully I was just not shifting right. | ||
| Aaron |
I've always had a big problem with that terminology, "theoretical" top speed, when people use it based on gearing alone. Like that Chrysler abomination for which they claimed a 400mph "theoretical" top speed. It ain't much of a theory if you don't consider the power it takes to pull it, and the 500hp or whatever that thing had wasn't even close to enough power to pull 400mph. Gearing a bike taller can just as easily lose you top speed as gain it. | ||
| Turnagain |
most recent claims I've heard are 300mph. maybe one of the folks that spend $250,000 to get one of the ten will put it to the test and be real surprised with the result.  | ||
| Fullpower |
wycked: the owners manual is WRONG. it lists a 29 tooth front belt pulley on the XB12. my XB12 came stock with a 27 tooth front pulley. the calculated rpm/ speed ratio is consistent with a primary ratio of 38:57 and a final drive ratio of 27:65. this gives an overall ratio of 3.61 engine revolutions per wheel revolution in 5th gear. rpm x D / 336 G = MPH where D= tire diameter in inches G= overall gear ratio so 6800 rpm x 25 inches /( 336 x 3.61 ratio)= 140 MPH that is calculated speed of XB12 at rev limiter. variables or inaccuracies result from tire growth/ tread wear, wheelspin, tachometer tolerance, windspeed/direction, and how much of the rider is sticking out in the breeze. Your Mileage May Vary | ||
| Wyckedflesh |
FP, that was why I posted what was in the owners manual AND what was in the service manual. I trust the service manual more personally. My thought though was that the owners manual had to get the 29tooth idea from somewhere and that is what he ended up with, since it was ment for a 12 the 9 he was riding just wouldn't have the umph to utilise the new gearing. | ||
| Fullpower |
the 29 tooth front sprocket was likely for a european version, for some reason, they often gear export bikes a bit taller. i have not seen any 29 tooth models in person, but the referance in the owners manual is interesting, although in error. | ||
| Fullpower |
blake, if you regeared the final drive, you would indeed cause inaccuracy in the speedo, which is driven by the transmission output shaft. | ||
| Austinrider |
Well, I got the bike street rideable again. I rode into work and managed to get the bike up to about 105-110 and still had a bit to go on the tach. I'm going to see if I can get it on the dyno here soon and do a few runs there to see what I find. Im thinking the bike is going to top out at about 120 though. At least thru my guesstimates judging rpm and speed that what I expect to get out of it. Thats still plenty fast, just good to know for when I take it to the track with the long straigts (like TWS). I think it will be ideal for a track like Texas Motorsports ranch where the straights are alot shorter. Only time will tell. <goes back to working on body positioning and getting thru the turns with greater speed> | ||
| Prof_stack |
Most freeways have mileposts. You could time, at 60 mph, how many seconds it takes to go one (or more for accuracy) miles. 60 seconds @ 60 mph = 1 mile. Probably safer than doing 110 on the roads... | ||
| Buelluk |
Or as mentioned in previous threads ,get a Garmin GPS and mount it up...these will give a good comparo to the stock speedo. | ||
| Skully |
Guys, The parts manual for my 2003 XB9S lists the front sprocket as having 30 teeth and the rear as having 72. This yields a ratio of 0.4167. The '04 belt upgrade I just purchased from Dave lists the front as 27 and the rear as 65 yielding a ratio of .4154. This is less than 1/2% difference in ratios. Keith | ||
| Austinrider |
Keith - Have you had a chance to top out 5th gear? Im really interested in what your top speed is. Phil | ||
| Skully |
I've been 125-130 (indicated) and there was still a *little* bit left. Keith | ||
| Austinrider |
Just a little update on this. I spoke to the Mechanic who did the change on my bike. When I told him what I noticed he confirmed that the pulleys were different sizes and that he suspected my top speed would be lower. He offered to look into it, and see if something could be done. I told him dont bother, this is going to be mainly a streetbike here soon and I wont need that kind of speed on the streets. |
