Speedometer discrepency queshun
10-22-2007 | 06:59 PM
#1
Thread Starter
WERA #44
Superstock
Joined: Jul 2007
Posts: 265
From: About 57 miles south of VIR
Speedometer discrepency queshun
OK, So debut ride for the Phoenix Project was yesterday. Seat of the pants says about 55-60, and the clock says70 to 75. My buddy was riding my old GSXR and he said I was doing 70 most of the time, but it felt slower.
The GSXR is probably inaccurate, and the hawk has a 15/43 set on it.
So, What is norm for this bike w/ the stock gears or the 15/43?
Respondents will be awarded free ice cream at the poor farmers country store in Meadows of Dan Va.
Thanks, Rob
The GSXR is probably inaccurate, and the hawk has a 15/43 set on it.
So, What is norm for this bike w/ the stock gears or the 15/43?
Respondents will be awarded free ice cream at the poor farmers country store in Meadows of Dan Va.
Thanks, Rob
10-22-2007 | 08:18 PM
#2
Senior Member
MotoGP
Joined: Aug 2007
Posts: 2,547
From: Way Out West
I figure the 15/43 sprockets lower the effective gearing by about 11%. Indicated 70mph. with 15/43 would be about 63 mph. with the stock sprockets.
The stock VTRs were reported by magazine testers to have spot on speedos at indicated 60 mph. Don't know if that held for other speeds.
The stock VTRs were reported by magazine testers to have spot on speedos at indicated 60 mph. Don't know if that held for other speeds.
10-25-2007 | 05:19 AM
#3
Senior Member
Back Marker
Joined: Dec 2006
Posts: 240
From: Jacksonville, NC
I figure the 15/43 sprockets lower the effective gearing by about 11%. Indicated 70mph. with 15/43 would be about 63 mph. with the stock sprockets.
The stock VTRs were reported by magazine testers to have spot on speedos at indicated 60 mph. Don't know if that held for other speeds.
The stock VTRs were reported by magazine testers to have spot on speedos at indicated 60 mph. Don't know if that held for other speeds.
10-25-2007 | 09:42 AM
#6
Banned
MotoGP
Joined: Aug 2007
Posts: 5,942
From: Lake View Terrace, CA
I figure the 15/43 sprockets lower the effective gearing by about 11%. Indicated 70mph. with 15/43 would be about 63 mph. with the stock sprockets.
The stock VTRs were reported by magazine testers to have spot on speedos at indicated 60 mph. Don't know if that held for other speeds.
The stock VTRs were reported by magazine testers to have spot on speedos at indicated 60 mph. Don't know if that held for other speeds.
10-26-2007 | 11:23 PM
#7
Junior Member
Squid
Joined: Jul 2007
Posts: 10
From: Carlisle, PA
I'll admit I don't know exactly how the speedohealer works because I don't have one yet. this winter I'm planning on doing a 520 conversion w/ 15/43 gearing and a speedohealer. I'm just wondering where you set yours to be spot on with your GPS since I don't have easy access to a GPS to check mine. Thanks.
10-27-2007 | 06:26 AM
#9
Senior Member
MotoGP
Joined: Aug 2007
Posts: 2,547
From: Way Out West
To expand on my post #8, I think it through this way;
When you go minus one on the 16 tooth front sprocket, you are increasing engine speed at any given road speed by 1/16th right? 1/16th expressed as a percentage is (100 divided by 16) is 6.25% increase in rpm.
Each tooth up on the 41 rear is a 1/41st increase in rpm, or (100 divided by 41) = a 2.439% increase in rpm. Two teeth up is (2.439 X 2) = a 4.878% increase in rpm.
Total increase in engine rpm at given road speed with 15/43 sprockets is (6.25 + 4.878) 11.128%
The VTR with stock sprockets turns 3100 rpm at 60mph in 6th gear.
A VTR with 15/43 would be showing 3500 rpm in 6th at 60mph.
When you go minus one on the 16 tooth front sprocket, you are increasing engine speed at any given road speed by 1/16th right? 1/16th expressed as a percentage is (100 divided by 16) is 6.25% increase in rpm.
Each tooth up on the 41 rear is a 1/41st increase in rpm, or (100 divided by 41) = a 2.439% increase in rpm. Two teeth up is (2.439 X 2) = a 4.878% increase in rpm.
Total increase in engine rpm at given road speed with 15/43 sprockets is (6.25 + 4.878) 11.128%
The VTR with stock sprockets turns 3100 rpm at 60mph in 6th gear.
A VTR with 15/43 would be showing 3500 rpm in 6th at 60mph.
Thread
Thread Starter
Forum
Replies
Last Post
wardo996
Classifieds
0
03-21-2007 11:20 AM
