motojoeyt
Novice Class
Posts: 75
|
posted September 04, 2013 11:15 PM
Is GPS accurate?
Hello gentlemen,
Shorten my bike back up to stock and put some long gearing on it (Temporary until the tracks open back up in Phoenix). Went out with some buddies tonight with the GPS in my pocket and did a few high speed pulls. Went high 170's no problem and was still climbing hard. On the last pull I knew I had to take advantage of our big tail wind and run it out the back door. Took it to 1-200rpm before redline in 6th and when I got home I was pleasantly surprised it said 200mph! As much as I would like to believe it I think the GPS might be off. I don't think I had enough gearing from the get go and it was still pulling and cant forget it was still 90* in the desert with a 2 year old dyno tune map in it? So I guess my questions are:
Has anyone done accurate testing with GPS?
Track to GPS comparison?
What gearing do the 12's needing for 200?
As always thank you guys for your input!
Joey Terranova
____________
8.81@154 DOT/Pump full street bike
  
|
shiphteey
Needs a job
Posts: 2529
|
posted September 05, 2013 06:48 AM
GPS Can be accurate. Some of it has to do with where its mounted. If you stuff it in your tail section or in your breat pocket you can get weird numbers. I've got 250 mph on GPS on my Ninja 250 once....obviously a far cry from 111 mph.
I've also seen the 12R get weird numbers because I had it in my jacket breast pocket...signal had trouble going through torso apparently. I prefer on the bike with a good signal like top triple clamp, gas tank or top of rear seat.
Stock gear, tire and rev limiter is theoretically 203 mph or so. In the real word its 196. Also cheaper units will round to the nearest integer....so a 199.5 or a 200.4 will show a 200.
A big tailwind helps overcome certain limitations. I'd say its possible you did it...I'd just need more info to give you an idea.
Have fun, be safe.
A.
____________
Gemini Motorcycles
Topping out everything from Ninja 250s to nitrous ZX-14s.
|
shiphteey
Needs a job
Posts: 2529
|
posted September 05, 2013 06:51 AM
Also there are some places that have dead zones....sometimes its cloudy.....but overall I've found GPS, if setup right to be consistent to the 1/10s mph.
____________
Gemini Motorcycles
Topping out everything from Ninja 250s to nitrous ZX-14s.
|
motojoeyt
Novice Class
Posts: 75
|
posted September 05, 2013 11:05 PM
Hi Shiphteey,
First of all thank you for thoughts. As far as my gearing i am running a 18(stock front) and a 45(1 down) in the rear. The rear tire is a shinko 180-50. I have not done the math but I'm thinking the gearing should be extremely close to stock with the tire size difference. For the GPS, it is an app on my phone, which in the north phx area is around 40Mbps down loading speed on 4G network that was located in my jean pants pocket.
As far as your comment "stock gearing, tire and rev limiter is 203, real life 196" I find to be strange because i ran Texas mile with stock gear with a smaller motor and ran 186 at redline in 6th? But then again it is hard to disagree when looking at your track record going 220 with a head wind!
Thanks again,
Joey Terranova
____________
8.81@154 DOT/Pump full street bike
|
motojoeyt
Novice Class
Posts: 75
|
posted September 10, 2013 11:39 PM
Has anyone else done GPS testing against real world mph?
Thanks,
Joey
____________
8.81@154 DOT/Pump full street bike
|
psycho1122
Pro
Posts: 1608
|
posted September 11, 2013 05:13 AM
Yes, back in 2001, with around 2,500 ft. DA... I went 196 with stock gearing and rear tire. Only a map and pipe at the time (Doug Meyer's)
We did the runs out on the 387 early in the A.M. We used a real GPS and Paul Dean's (Cycle World Mag. ) Radar gun. Both were within .6 m.p.h. of each other.
Funny though.... my speedo showed just under 220 when I got a short glance at it...LOL.
____________
You say PSYCHO like it's a BAD thing!!
|
shiphteey
Needs a job
Posts: 2529
|
posted September 11, 2013 10:22 AM
First of all thank you for thoughts. As far as my gearing i am running a 18(stock front) and a 45(1 down) in the rear. The rear tire is a shinko 180-50.
----I did not know they made a 180/50....maybe you mean 180/55 or 190/50.
I have not done the math but I'm thinking the gearing should be extremely close to stock with the tire size difference.
----Close enough for the purpose of this discussion I suppose.
For the GPS, it is an app on my phone, which in the north phx area is around 40Mbps down loading speed on 4G network that was located in my jean pants pocket.
As far as your comment "stock gearing, tire and rev limiter is 203, real life 196" I find to be strange because i ran Texas mile with stock gear with a smaller motor and ran 186 at redline in 6th? But then again it is hard to disagree when looking at your track record going 220 with a head wind!
----Redline? The party don't stop there unless you're on a choked up stock exhaust system. Redline indicates 11,500....rev limiter about 12,200 indicated. You saying you went 186 at redline doesn't necessarily negate me saying the additional RPMs will go 10 more mph. How sure were you that you saw exactly 11,500? Texas is a lil bumpy...with my chin on the tank my head bounced around a lil...not much....but the eyeballs can play a little trick on you and picking up 100 rpm differences isn't easy as you get going faster and faster. But I think you get the idea. Redline doesn't mean rev limiter.
18/45 and a shorter tire is still kinda close to stock 18/46 and a stock 200/50 tire. So in other words...I think even if you pulled to the rev limiter you may come up juuuuust shy of 200. Change your tire to something larger in circumference or if its got good tread just spring for a cheap 44T rear.
A.
Thanks again,
Joey Terranova
____________
Gemini Motorcycles
Topping out everything from Ninja 250s to nitrous ZX-14s.
|
2000redrocket
Pro
Posts: 1662
|
posted September 11, 2013 01:41 PM
so rev limit stock is 11,700 where ever the tach is when it hits the limiter it is 11,700
|
motojoeyt
Novice Class
Posts: 75
|
posted September 11, 2013 03:12 PM
Hi Shiphteey,
Regarding the180 shinko tire you are correct it is a 55 series (sorry typo). I didnt find Texas bumpy at all and with that being said i am possive it was exactly at red line in 6th. It was climing so slow in 6th for the last 1/4 mile i had a ton of time to look at it. My rev limiter is also 11.7 like 2000redrocket. Did you bump up your rev limiter?
Since I ran that night I changed my gearing and went one down in the front. To much sliding the clutch with stockish gearing for dragracing. Beside 200 is to fast for the street.
Shiphteey, you do run a 12 correct? If so, what gearing are you running for 220mph?
Thanks again for everyones input!
Joey T
____________
8.81@154 DOT/Pump full street bike
|
Shane661
Needs a life
Posts: 11494
|
posted September 11, 2013 04:03 PM
 Edited By: Shane661 on 12 Sep 2013 00:05
Most GPS units update at 1hz (1 refresh per second). The less below terminal speed, the less accurate it is. At 175 mph, for example, you may be gaining more than 1mph per second. If your GPS has higher refresh, different story.
Shane
|
2000redrocket
Pro
Posts: 1662
|
posted September 11, 2013 05:13 PM
i my self did bump my limiter to 12000. and a friends to either 12300 or all the way to 12,500.
my limiter hit tach wise at 12,200 or so now 12,500 on tach
|
motojoeyt
Novice Class
Posts: 75
|
posted September 19, 2013 09:04 PM
Redrocket,
How did you change your stock rev limiter, stock ECU retune? I don’t even think I would want to run my engine that high as I'm very high compression and would worry about stretching and hitting stuff. That is bad!
Thanks,
Joey
____________
8.81@154 DOT/Pump full street bike
|
|
|
HOME
NEW TOPIC