Speedometer accurate on vintage scooters?
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Addicted
2016 LXV 150 ie, 1978 Vespa P125, 2019 Piaggio Liberty 150
Joined: 06 Jul 2016
Posts: 531
Location: central Illinois USA
Tue May 28, 2019 3:27 pm quote
Now that I have mine running and am riding it I am sure that speedo is not at all accurate. Had a couple pals follow me to the next town, my Ď78 P125x speedometer seemed to think that 55 was the max speed it was moving, guys following me, 1 on a Ninja, the other on a 250 Honda Rebel said they were running 65 or faster to keep up with me.
I did a bit of lubricating with something for chains and cables and havenít had a change to take the scooter out on the road and see what sort of speeds it will register/clock.
Iím ok with it not being accurate but I donít want to try and explain to my adult sons why their Mom needs bailed out of jail some day for trying to fly that little ride with no pilotís license.
Any suggestions on what I might want to try and do to improve the accuracy or at least the working of that speedo?
Ossessionato
BV350, Primavera 150, Yamaha Zuma 125
Joined: 06 Jun 2013
Posts: 2803
Location: The Twin Cities of Minneapolis/Saint Paul, Minnesota
Tue May 28, 2019 4:35 pm quote
Chances are, your friends weren't going as fast as they thought they were. Lots of motorcycle and scooter speedometers run optimistic; yours could be the exception that doesn't.
Ossessionato
1976 Super (x 2), 1974 Primavera (x 2), 2006 Fly 150
Joined: 26 Sep 2013
Posts: 4871
Location: So Cal
Tue May 28, 2019 4:46 pm quote
Download a GPS app.
Hooked
1974 Vespa Primavera 125, 1980 Bajaj Chetak
Joined: 07 Jul 2017
Posts: 414
Location: Boston, MA
Wed May 29, 2019 5:25 am quote
Definitely download a GPS app or even just use Waze to compare the speedo with your actual speed. Vintage Vespa speedos definitely aren't accurate - I think most people find them to be about 5 mph off. That said, many modern ones aren't either.

Last edited by Bazziemoto on Wed May 29, 2019 8:18 am; edited 1 time in total
Molto Verboso
2009 GTS 250, 2013 Buddy 125, 2014 Triumph Bonneville
Joined: 23 Apr 2016
Posts: 1799
Location: North Jersey
Wed May 29, 2019 6:00 am quote
JKJ-FZ6 wrote:
Chances are, your friends weren't going as fast as they thought they were. Lots of motorcycle and scooter speedometers run optimistic; yours could be the exception that doesn't.
This ^
All modern auto and motorcycle speedometers indicate up to 10% higher speed than actuality. ( probably so you can't blame the manufacturer for your speeding ticket) Your NSM most likely is the more accurate one, IMO.
Moderibbit
1980 P200E - "Old Rusty", 1976 ET3 Primavera
Joined: 12 Jun 2008
Posts: 8129
Location: Atlanta, GA
Wed May 29, 2019 9:31 am quote
Mine's roughly 7mph faster than the speedo indicates, based on GPS. I doubt there's anything to be done about it. I just know, and ride accordingly. Also, in reality, I almost never pay attention to my speedo, but rather the speed of the traffic and what's safe for the road surface and riding conditions. Not that I advocate speeding - it's just that especially on a PTW you want to be in control and not a target, so those are my personal priorities
Ossessionato
73 Rally, 74 Rally, 76 ET3, 80 P200, 63 Li125, 65 Li225 Silver Special, 86 Elite 80, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 3258
Location: Oceanside/ SF
Wed May 29, 2019 10:22 am quote
Out of all the scoots I own, only one is accurate. Thats sadly because I had it rebuilt by Speedo king. In addition to what everyone else has said, replacing or rebuilding your speedometer is one way to get some accuracy. That averages around $100 so its not for everyone.
Molto Verboso
Joined: 26 Oct 2015
Posts: 1731

Wed May 29, 2019 11:22 am quote
Strangly enough, of all the P200's that i've owned, i had a random one which the speedo would read 55mph while the GPS would show 67mph. I'm not sure what happend at the Piaggio factory that day to cause that anomaly. One of my current P200's has a fairly accurate speedo...it's within about 1-1.5 mph. As for all my other scooters? The speedos read about 8mph faster than what i'm actually going. I did disassemble the speedo on my '05 PX150 and recalibrated it to be dead on with a GPS.
Addicted
Honda elite
Joined: 19 Jun 2007
Posts: 576
Location: California
Wed May 29, 2019 11:22 am quote
if costs are not prohibitive maybe SIP has an upgrade to the original with options for temp and RPM metering
Hooked
1974 Vespa Primavera 125, 1980 Bajaj Chetak
Joined: 07 Jul 2017
Posts: 414
Location: Boston, MA
Wed May 29, 2019 12:52 pm quote
MJRally wrote:
Out of all the scoots I own, only one is accurate. Thats sadly because I had it rebuilt by Speedo king. In addition to what everyone else has said, replacing or rebuilding your speedometer is one way to get some accuracy. That averages around $100 so its not for everyone.
I just had one rebuilt by Speedo King but I'm pretty sure it's still 5mph over. I'll have to double check.
Molto Verboso
2005 PX150 In a Love-Hate Relationship with a 2-Stroke Vespa Since 2007
Joined: 01 Sep 2007
Posts: 1812

Wed May 29, 2019 1:56 pm quote
For the vast majority, nope.

Mine indicates about 8% over plus 5, according to my GPS app.
Hooked
PX 150
Joined: 06 Aug 2007
Posts: 310
Location: Dublin, Ohio
Wed May 29, 2019 5:06 pm quote
My PX has a very optimistic speedometer. Maybe it is an Italian thing because my Ducati is the same way and that speedo is all digital. There is no cable. I just made a label and stuck it on the headset above the speedo. The top line is the speed I want to travel and the bottom line tells me how fast the speedometer should be reading for that speed.

8E3A9DA1-CE00-454A-B5BB-3EF076352351.jpeg

Ossessionato
1976 Super (x 2), 1974 Primavera (x 2), 2006 Fly 150
Joined: 26 Sep 2013
Posts: 4871
Location: So Cal
Wed May 29, 2019 5:27 pm quote
According to the speedometer, my smallie is going 20mph parked in the garage

image.jpg

Molto Verboso
08 GTS 250, 79 P200E, 62 Allstate
Joined: 11 Jan 2006
Posts: 1284
Location: Florence, OR
Wed May 29, 2019 6:39 pm quote
Out of 5 scooters, only one is accurate to +-2mph. One reads 5 mph slow consistently. That kind of surprised me because all the other speedos are optimistic.
Ossessionato
BV350, Primavera 150, Yamaha Zuma 125
Joined: 06 Jun 2013
Posts: 2803
Location: The Twin Cities of Minneapolis/Saint Paul, Minnesota
Wed May 29, 2019 6:47 pm quote
SoCalGuy wrote:
According to the speedometer, my smallie is going 20mph parked in the garage
That's because red is the fastest color.
Addicted
Joined: 26 Jan 2019
Posts: 638
Location: california
Wed May 29, 2019 7:52 pm quote
Quote:
That kind of surprised me because all the other speedos are optimistic.
Some scooters see the glass half full.
Some see it half empty.
Doesn't make it a bad scooter.

Maggie:
At risk of exposing my comfort with hack solutions - if you just want to confirm accuracy the speedo app is simple and free.
Once you download, open the app.
Use a piece of rubber sheet or old inner tube if you have it (folded paper towel will also do) - place under your phone, and (here it comes) use electrical tape to connect your phone to your headset.
Wrap the tape 360 degrees around bars at least twice.
One wrap at one end of phone.
Another at the other end.
It will not remove your paint.
It will not damage your phone.
Fold the ends of the tape so you can quickly unravel without fighting to remove it - and no none will see that you had your phone taped to your scoot when you pull back in.



With a couple runs, you can even create a little translation so you know the major speed indicators true speeds.

There are also some nice holders available if you want something a bit more permanent - but for a one or two time run - electrical tape is your friend.
Hooked
1974 Vespa Primavera 125, 1980 Bajaj Chetak
Joined: 07 Jul 2017
Posts: 414
Location: Boston, MA
Thu May 30, 2019 8:19 am quote
SoCalGuy wrote:
According to the speedometer, my smallie is going 20mph parked in the garage
I had this issue. The needle was bottoming at 15mph. It means the drive is going. Speedo King can fix that for you for about $60.
Addicted
2016 LXV 150 ie, 1978 Vespa P125, 2019 Piaggio Liberty 150
Joined: 06 Jul 2016
Posts: 531
Location: central Illinois USA
Thu May 30, 2019 2:45 pm quote
Some great suggestions but not all workable, a lot of dead zones in my riding world, and that smart phone is usually in a pocket, often on Ďairplaneí. The speedometer has an issue, speeding up does not make it go beyond 55, ok, actually 1 time it did. I have done some lubricant and will see if that helps it work better/smoother. It had been stored for a very long time before it was sold or donated to the 30 Days Gang for the last rally. I donít think they did anything with that speedo, so itís possible that it just needed some cable lube.
I might get a mount for the phone some day but I would rather it was out of sight and out of mind... vintage stays home tomorrow and the LXV goes to work, LOL, it has basket and I pick up a case of bacon after work, easier to bring home the bacon on the LXV than try and fasten it and lunch box on the baby.
Hope to run to Springfield early Saturday morning IF it is Not raining again!
Member
77 Sprint Veloce
Joined: 13 Sep 2018
Posts: 44
Location: Los Angeles
Sat Jun 08, 2019 5:36 pm quote
100+ Kph parked with a broken cable.

IMG_20181014_163409.jpg

Enthusiast
P125X/Apr 500/CH150/P200
Joined: 28 May 2015
Posts: 59
Location: Long Beach, CA
Sat Jun 08, 2019 6:22 pm quote
What's your secret ? I can't seem to get my P125 over 50 going downhill with a tail wind. One good thing, this speedo was rebuilt by Speedo King and it matches the GPS within 1 MPH.
Molto Verboso
Joined: 26 Oct 2015
Posts: 1731

Sat Jun 08, 2019 10:49 pm quote
RJY wrote:
What's your secret ? I can't seem to get my P125 over 50 going downhill with a tail wind.
A steeper hill...much steeper.
Molto Verboso
Joined: 26 Oct 2015
Posts: 1731

Sat Jun 08, 2019 10:56 pm quote
apex wrote:
My PX has a very optimistic speedometer. Maybe it is an Italian thing because my Ducati is the same way and that speedo is all digital. There is no cable. I just made a label and stuck it on the headset above the speedo. The top line is the speed I want to travel and the bottom line tells me how fast the speedometer should be reading for that speed.
I have four of those 2005 PX150's, and the speedo inaccuracy on all four match yours Apex. On one of the speedos, I removed the chrome ring and plastic lens to get at the speedo needle. I installed GPS on the scoot, then went out on a speed test ride. I removed the needle while riding at a set speed on a GPS (55mph), and pressed the needle back on so that it pointed right at 55MPH...and BOOM, accurate speedo.

I haven't tried it on any other scooters, so I don't know if that trick will work on them.
Molto Verboso
2005 PX150 In a Love-Hate Relationship with a 2-Stroke Vespa Since 2007
Joined: 01 Sep 2007
Posts: 1812

Sat Jun 08, 2019 11:30 pm quote
^^^ If it were only that simple on my 05 PX150.

I found that the variance was not simply an offset. I recorded the GPS speed when the speedo read 10, 20, 30, 40, 50 mph and the faster I went, the more the difference read on the speedometer. I plotted it out on a spreadsheet and found it to be a linear function approximately 8% over the real speed + 5 mph. This suggests not just an 5mph offset but a wrong gear or tire size somewhere. But I doubt it's tires because I use Heidenau K38s which have a slightly bigger circumference than the Michelin S83s it came with, which if anything would compensate for an overly optimistic speedo.

I haven't tried to fix it. There's always something else more important to wrench on. I just assume I'm going a minimum of 5 mph less than whatever it says.
Addicted
2016 LXV 150 ie, 1978 Vespa P125, 2019 Piaggio Liberty 150
Joined: 06 Jul 2016
Posts: 531
Location: central Illinois USA
Sun Jun 09, 2019 4:15 am quote
Thank you all who have posted, and the poor speedo and of course that odometer are probably needing a trip to the specialist who Ďtreatsí such treasures. Iím thinking some rather old parts are needing to be replaced and itís not a Maggie job. I can replace the parts up to that speedometer but I know if I have the funds, this coming winter it will go to be rebuilt. Or I will replace it with new and put the original away until I can afford to have it rebuilt. In the meantime, I can keep on riding, and make sure in small towns known for handing out speeding tickets that they are giving them to cagers and not old woman on a vintage Vespa!
Hooked
1974 Vespa Primavera 125, 1980 Bajaj Chetak
Joined: 07 Jul 2017
Posts: 414
Location: Boston, MA
Mon Jun 10, 2019 4:57 am quote
maggiegirl wrote:
Thank you all who have posted, and the poor speedo and of course that odometer are probably needing a trip to the specialist who Ďtreatsí such treasures. Iím thinking some rather old parts are needing to be replaced and itís not a Maggie job. I can replace the parts up to that speedometer but I know if I have the funds, this coming winter it will go to be rebuilt. Or I will replace it with new and put the original away until I can afford to have it rebuilt. In the meantime, I can keep on riding, and make sure in small towns known for handing out speeding tickets that they are giving them to cagers and not old woman on a vintage Vespa!
You will likely spend more on a replacement speedo than a repair. Also, if you're worried about your speed, just use a phone mount and a speedo app.
Ossessionato
2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
Joined: 26 May 2013
Posts: 3819
Location: Millbin, Ostrayleea, mate
Mon Jun 10, 2019 5:03 am quote
Its perfect!
Speedy's Speedo is awesome & completely accurate... its somewhere in a box & reads 23mph all the time!
Hooked
1965 Allstate
Joined: 27 Jul 2017
Posts: 158
Location: Cleveland, Ohio
Mon Jun 10, 2019 10:27 am quote
I always just subtract 7 from what the speedometer says.
Veni, Vidi, Posti
a not so normal vbb2 '64, a weirdo vbx '86 and a not so normal pts100 '82
Joined: 15 Jun 2009
Posts: 5482
Location: Indo
Tue Jun 11, 2019 1:34 am quote
I dont have a active speedo, so i dont have a captain log, but the wind always tells me if i am going to fast, which is rare
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