uchi

I ended up downloading another program. I think the one I had was just a viewer. The new program works great. Thanks again for the spreadsheet. The top speed really takes a dive with the 15/43 setup. Lol

nath981

how can that be when you can't get max rpms in sixth with oem gearing?

RK1

"Cause a stock VTR will pull 155 mph but one with 15/43 redlines in 6th at about 148 mph.

autoteach

Ummmmm, I am unsure of the quoted top speeds we are showing. Are we talking per speedo, or corrected speed? Per speedo, top in 5th is 162 and top in 6 would be theoretically 180ish. Actual would definitely be off of that, and so your calcs may be figuring. I can't imagine that a 15/43 would drop the gearing so much that you would peg the limiter in 6th, but then again I have only had the 16/43. Hell, I don't even know what I am talking about right now, what's the topic?

RK1

There is a formula for calculating theoretical top speed considering crank rpm., all gearing reduction to the rear wheel and circumference of rear wheel. I can't remember what it is but back when I plugged in the VTR values I came up with 169 mph at redline in 6th. Tweety's program says 166 mph. Close enough.

PS The 155 mph I quoted is from several published road test, I assume from radar. The other ones are calculated.

PS2 15/43 produces an 11% change in rpm vs. road speed. So a bike which (if it could pull it) redlines at 166 mph in 6th would now redline at 148 in 6th. (166 X .89 equals 147.74)

RK1

On a side note;

I'm not interest in going 166 OR 148 on the street, but if your goal was to squeeze highest top speed from a stock engine VTR, then 16/41 is too tall and 15/43 is too short.

uchi

im more concerned with the cruising rpm more than anything. ive been near the end of the bikes limited 6th gear a couple times so i guess in theory i can still reach the same top speed mainly because the bike wont hit redline in 6th and if it does now or comes closer then technically i can hit the same top speed. either way 15/43 is alot of fun

8541Hawk

The bike does pull to redline with 16\43 gearing with a top speed of either 156 (my calculations) or 159 on a 6th gear dyno pull.

Personally I don't see how you guys ride with 15\43 gearing. I'm a fat guy and still can't keep the front end down with 16\43 gearing. You would think that 1st gear would be almost useless with a 15\43.

uchi

im a fat guy too, thats why i wanted 15/43. i was originally gonna go 15/42 but decided on this instead. the 2 hour ride i had monday proved one thing. 3/4 throttle the front end will stay down in first, sometimes, second gear she either wants to lift if i roll on hard or, and this happened a couple times because the roads were super clean, the back tire will break traction. but thats only because the roads werent summer perfect. after that the higher gears are alot of fun to play in.

heres a safety question. what if i were to put the bike up on the front and rear stand, fire it up put it into 6th gear and run it out to redline, how safe would that be? i can se it from both points of view but im wondering if anyones ever done that?

comedo

The speedo shows speed based on the rate of rotation of the drive sprocket. The number of teeth on the sprocket doesn't matter. If you're in sixth gear at the redline, the speedo will show the same speed regardless of gearing. That's why people use Speedohealers.
It would be exciting to see how fast the rear wheel spins with the bike on stands but it wouldn't tell you much more than how lucky or unlucky you are that day.

uchi

oh i know that, i remember when i regeared my mustang it wasout like 40 kph, lol. ive got a speedohealer in thats why i wanna do the stand thing, see where 6th will theoretically top out if my adjustments were correct

RK1

There is no way around the math. If you're running 15/43 sprockets 6th tops out (red line) at 148 mph. (237 kph) 'cause you've given away 11% of your final drive ratio.

Going by the speedo healer assumes that the speedo was dead accurate in the first place, which is highly unlikely.

RK1

In other words, If you spin the wheel to red line in 6th and it reads anything BUT 148/237, what it's showing is the percentage error in the speedometer readout, not the actual wheel speed. It may vary slightly, depending on how much rubber has been worn off the tire since it was new.

uchi

Makes sense. Although assuming the math is correct you can take the rpm from 6th at 60 mph and compare it to the spreadsheet and figure out how much to correct the speedohealer

Dan Cronin

The main thing to remember is its the wind resistance that you are trying to overcome. Running on a dyno is useful for tuning but won't tell you much about the top speed the bike can achieve.

Recall the last time you were tucked in behind a tractor trailer with the box was breaking the wind for you. If you held the throttle at the same position and moved out from behind the rig, say into the next lane, you'd need to add >> throttle to keep the same speed.

FWIW, I can't imagine anyone being disappointed with 15/41 - 15/43. All give an extra kick w/o hurting top end such that you would notice. For the amount of time we spend between 50-130 vs above 140, considering the roads and traffic, its an easy choice to make.

uchi

true enough, im definatly not disapointed by it, but having not ridden the bike since october it just felt like it was screaming at 110 mph compared to where it was at before

nath981

that makes sense then. you're saying that even though you can't reach max rpm in 6th(OEM gearing), your top speed will still be greater than it would if you have 15/43 at max rpms. Well i changed mine to 15/44 and love it, but then I don't care that much for maximum straight line speed anymore. Leaning is where it's at for me, but screwing it on for top speed is still fun occasionally just for the rush.HaHaHa

nath981

+1 and I went from 43 to 44 rear and like it better, and that pulled the wheel forward to shorten up the wheelbase about 3/4 inch from where it was previously. I like it.

uchi

haha thats things gotta wheelie like a retard now with a shortened wheelbase. how do you like the handling? do you find it turns in alot sharper?

nath981

I'm happy with the handling, but can't say definitively that I can tell the difference shortened wheelbase. If someone else had done it and didn't tell me what they did, I may have been able to feel it. When I put the new chain on, I had to cut it to length and I cut it as short as possible for the 43 tooth vortex. Since that piece of **** started to wear quickly, I immediately bought the best AFAM alum 44 tooth and when I put it on it brought the axle up real close to front of the swingarm. That made me happy(that's how easy I am to entertain.hahaha).

that said, I firmly believe that getting **** about every little thing to improve handling, performance, etc., is important for safety on the street if you ride aggressively, and on the track to be competitive, i also feel that good riding skills can trump many of these mechanical improvements. Trail braking has done more for handling than any and all mechanical improvements that I've made over the past 10 years i've owned my SH.

Wheelie easy. It definitely helps to get the front airborne with merely a quick twist in first without sitting back of compressing/extending the forks,, or pulling back and that makes me happy. See what I mean.haha

uchi

sounds like youre amused as easily as i am, we should be friends

nath981

i'm headin for the fridge right now to get a cold one. I'll toast to that at exactly 7:35pm. ready?

nath981

aaaahhhhhhh! that Yuengling Lager tastes mighty good. Cheers to ya uchi!

uchi

thanks buddy cheers to you too, i toasted all night last night

nath981

hell, I got half drunk waitin. I'll drink one for ya, to ya, and any other excuse I can think of.hahaha

uchi

i find the best excuse is because youre thirsty. if you need to find a reason youre on the verge of quitting. and no one likes a quitter

nath981

how is it that canooks always have the good answers? Anyway, we must have answered all the 520 conversion questions and maybe a few other things too, or maybe we're just that's plural or "postwhores"

uchi

defiantly more of option b than option a.

we have the best answers because we have the best beer and it seems to bring us spiritual enlightenment when we drink it

Erik S.

Still here, well, not this weekend, hence the late response.

Of course there are no hard feelings. I saw the smileys and fired back with some. All good.

Erik S.