Author Topic: Gearing? (Read 3722 times)

PitterB4 · « **on:** October 04, 2005, 09:14:23 AM »

I'm thinking of setting up the B4 for just track duty. It depends on how the trackday budget looks over the winter but that's my thought anyway. Even if I don't, the question is still valid...

My local track is Pocono. The East course there is the one run most often by bikes. It's really tight and the B4 does very well on it. For me, it's mostly a 3rd gear course. There is one 2nd gear turn. The back straight takes you up on a NASCAR banked straightaway. I'm honestly not sure how long it is. I always need 4th gear. If I hit it right and carry enough exit speed in the preceding corner, I'm shifting before halfway down the straight and hitting the rev limiter right before my brake marker. If I hit 5th, it isn't really worth it because that's an extra downshift for the next corner which means I have to start my breaking a fraction of a second earlier. I end up up-shifting and then right back down - too much time off-power. Either way, I'm not maximizing my speed at the end of the straight.

That was a really long winded way of saying that I think I need to bump up my gearing. Is that the right answer? If so, how much? I'm thinking down 2 in the back but that is a totally uneducated guess. Right now, in the most of the corners I'm close to the right revs to get decent grunt (does the B4 have "grunt"???) at the exit. I don't want to be much lower RPM-wise there either (although that can be fixed with quicker exit speeds!). I realized that this is realatively cheap and easy mod and that I can play around with it even in-between sessions. I just was looking for input from some of the great minds of the board.

Last thing... The B4 is running GREAT!!! Holy crap have I been having fun with it lately.

By my last session at the track on Saturday, I was setting up the big bikes for passes really well. (the group I was in only allowed passing in the straights with the bikes straight up which ain't the B4's strength!) Lay back in the straight, carry LOTS of exit speed on the next corner and then by the time the bikes are back up.... ZOOOM!

mtbcrazy · « **Reply #1 on:** October 04, 2005, 09:41:53 AM »

Hey Rob,

No, I don't think the B4 has grunt, my old bike, a 1989 Moto Guzzi LeMans V had lots of grunt, but each piston was 25% bigger than the bandit's all together!

Haven't done a track day in 14 years (on a 600 Ninja with Keith Code in Topeka) so I can't help you there! I was glad to keep it on the course, and sad to see how little I was leaning on the video. It felt like I was ALL THE WAY OVER, but, sadly I was just about upright. It was amazing that I could make those turns with the bike SO upright!

They had ALL the gauges taped over, so I couldn't tell how close I was to red-line (and you get pulled if you over-rev), and I had ridden my Guzzi there that morning, it's red-line is 7,500! (And it pulled to that like you wouldn't believe! torque like a tractor!) Hard to get a handle on.

It wasn't as scary as driving a stock car at Lowe's Motor Speedway at 145! (or I'm 14 years older) The turn comes up pretty quick and looks too small with the wall right next to you at 145, and you BETTER make it! (IMHO)

Ron

tomacGTi · « **Reply #2 on:** October 04, 2005, 09:48:51 AM »

I would drop a tooth, maybe two in the back tops.

I'm sure there's some sort of gear calculator available but since that motor uses revs over torque, you don't want to over-gear either. You'll be in the same situation only a gear lower. That and it would take longer to get into the "meat" of the powerband.

I would say get another cush drive or two from someone to facilitate the swap. Those things literally fall off and would make gear changing a more painless endeavour, especially at the track.

Once again, useless VW knowledge. Been playing with gearbox ratios for years....

-Randy

gsxr400 racer · « **Reply #3 on:** October 04, 2005, 04:16:59 PM »

You wanna be in 6th on the back straight just about to hit the rev limiter! always gear for the longest straight away!

PitterB4 · « **Reply #4 on:** October 04, 2005, 10:16:01 PM »

Quote from: "gsxr400 racer"

You wanna be in 6th on the back straight just about to hit the rev limiter! always gear for the longest straight away!

Seriously? I wish I had a map of the course. The straight is SHORT. You want me to shift up 3 and then back down 3 all in less than 10 seconds - probably like 5???

I don't get it.

gsxr400 racer · « **Reply #5 on:** October 05, 2005, 12:59:13 PM »

that way you use only 345th or gear it for using 5 gears! but generally you gear for the longest straight! maybe you would only use 5 th and six at this track and bearly 4th ? Dont really know have never been there ! But my point is why have all them gears if ya dont use them you sure dont want to use the lowest ones cause the ratio is way shorter , you can pull longer in a higher gear!

PitterB4 · « **Reply #6 on:** October 05, 2005, 04:13:30 PM »

Hmmm... makes sense. Thanks, Jay. If I turn this thing into a track bike, I may do something more radical like that (and probably do a 520 conversion, too). Right now, I'd like to do something that I could live with on the street and would help on the track.

Anybody got a 44 tooth 525 (preferably a blingy Vortex!) they want to part with?