Speedo accuracy.

[spyug]

I had the 750 around the block this morning to see how the speedo was running. The dealer had said it was running fast and would not issue a certification because of it.

I think it may run a touch fast at low speed in 1st gear (i.e a walking pace) but at 50 kmph it seems ok to me.

How would you go about checking accuracy short of having a radar gun?

I'm not sure now how to proceed.

Any suggestions?

Cheers all.
Spyug.

 

[BassCliff]

What are they thinking?

What are they thinking?

Mr. spyug,

Oh good grief! All motorcycles have speedo's that read fast. They come that way from the factory. In an article about my bike from a 1979 magazine the author states the difference between indicated and actual speeds. What kind of bureaucratic nonsense are they putting you through now? Just changing your front tire causes variations in the speedometer readings between old tire and new tire, different size tires, etc.

You may not have them available in your neighborhood, but there are a couple of radar controlled speed indicators on local streets in my area. It's just a flashing sign that tells you your speed as you drive by. I keep meaning to "speed" by to check the accuracy of my speedometer.

If it's a mechanical issue that's causing false readings, you may be able to clean and lube the inner workings of your speedometer. I've read a few posts in the forum of folks trying it with limited success. Otherwise you might find a good used one on ebay. But who knows if that one will be any more accurate?

You can always have someone follow along with you in their car and compare speed readings. Tell them you're going to drive at 50 for a while and see what their speedometer reads, and vice versa, have them drive at 50 and see what yours reads.

Have you tried another certification center?

Thank you for your indulgence,

BassCliff

 

[catfishk]

mine reads LOW; but the tire may be bigger than stock. however, it is only noticeably slower at a higher speed, which makes me think the speedo is wonky. a smaller (lower profile or height, not width) than stock front tire will make it read higher
i'd rather mine read higher!

 

[Killer2600]

Mr. spyug,
Oh good grief! All motorcycles have speedo's that read fast.
BassCliff

I dunno about that, my gs750e reads right. That is unless the typical speed of traffic on a given road changes when I'm on bike instead of car.

Another way to check the speedo is with mile or km markers along the highway, see how many miles/km traveled your odometer indicates compared to how many miles/km the markers indicate traveled.

 

[jimcor]

If you really want to find out how much your speedo is off find a friend with a GPS unit. It will have a very accurate speed readout.

Quit taking your bike to that joker. Man, he's really jacking you around. Speedo off. They're all off. He's off, too!

 

[80GS1000]

Motorcycle speedos are notoriously inaccurate. The one on my GS is 5-10% optimistic.

You can also install an aftermarket speedometer to replace the stock one. There are two types. They're the kind that have a magnetic sensor on the front wheel to count wheel RPMs and therefore speed, and GPS, which uses a satellite to track your speed.

I used the former type on mine from Acewell:

 

[runewolf]

Honestly what is the world coming to! Take it to another shop. Just how is this guy checking it anyway? If he has a machine I'd ask him when the last time he had his machine calibrated. Tell him you have two speeding tickets that prove your spedo is working just fine thank you very much

I have yet to be on any bike, from a $100 beater to a $19k BMW that wasn't off from my GPS. All of them on the high side, so when my 750 is showing 50 mph the GPS is showing 48 (it keeps you from getting as many tickets lol).

 

[chuckycheese]

Wow!

Wow!

I hope our politicians in California don't 'catch wind' of that type of harassment...they would absolutely love it!:?

(By the way, I'm pretty sure my speedo is quite accurate.)

 

[Guest]

My speedo on my 1000 reads fast... about 10mph fast at cruising speed. My 1150 is real close.

 

[girlie_rider]

My speedo on my 82 GS 300 seems to read about 10 faster than I'm going. The day I told my husband I had it up to 65 on the highway (my second ride on the road) he told me I was crazy because he never got over 55 riding behind me and it's been like that ever since. He says it always 10 less than what I thought I was going.

 

[hotspur]

Dont know about my GS but my main ride, R1100RS reads 5KPH faster at all speeds by my GPS. A mate of mines Kwaka VN2000 read 115 when he was doing 100KPH. He bought a Speedo Doc and recalibrated his.

 

[girlie_rider]

Let me clarify my previous response. Mine is off on the speedo when I get to about 45 and faster. Under 45, its not that far off. It's very noticible when I get to 45 and faster. As a new rider I thught I was doing really well, until my hubby told me I needed to go alot faster and I told him I didn't want to be speeding and he told me I had to at least be up to the speed limit if I wanted to think about speeding tickets. That's when he told me I was doing 10 miles under what I thought.

 

[82gs1100]

my speedo on my 82gs1100g is accurate. you can also ask a police officer if he would run radar on you to see if your speedo is right.
in the us speedos can be off 4% of there range. meaning if u have a 100mph speedo it can be off by 4mph+or-

 

[dpep]

My speedos read UNDER actual speed on at least two of my bikes and I know I have the right sized front wheels. Our bikes have very simple mechanical speedos. A little gear on the front axle turns a cable which spins the gears in the speedogears.

I have never thought about it before but does anyone know if the speedo gear is the same part number for all GS's? I've replaced many of those over the years without giving much thought if my replacement came from the same model.

If you don't have a GPS another way to check your speed is find one of those trailers with a sign that shows your speed that police set up before road construction and other places they want you to slow down. The police here call them smart trailers. You can actually call the local police and ask them where they are going to be setup for the week.

 

[spyug]

Thanks for all the input. Much appreciate it.

The problem, as the shop manager says is that the speedo is running way over i.e showing 80 kmph when its doing 30 or so. As the bike is not street legal, I've been running around my neighbourhood streets so I can't get the speed to high but it didn't seem that way off to me (mind you its hard to watch the speedo in a residential area when you're loing out for kids and pets).

Yesterday, after the ride, I got the gearbox off and cleaned and regreased it as best I could. I tried to clean and lube the cable but could only get it from the bottom. I can't figure out how to get the fairing off and my factory manual is not at all helpful.

I din't think about the GPS and that is the best idea. My son has one so I'll borrow tha and give it a whirl today if I can get the time (wife has a long list of chores).

As far as going to another dealer I will if I have to but when they billed me the cost of the certification was included so they will sign off when I sort this out.

I'll let you know how this all turns out.

Thanks again.
Cheers,
Spyug.

 

[SPARKSS]

The dealer had said it was running fast and would not issue a certification because of it.

How would you go about checking accuracy short of having a radar gun?
I
Spyug.[/QUOTE]

A speedometer reading fast is safe at least! I can't imagine that a dealer would even take the time to know that firstly, and secondly imagine why they'd care.

You can check your speedo basically by checking your odometer reading through a measured km or even better by checking the measured distance between 2 known points say 10 or even 20km apart. This assumes that the speedo doesn't jump or otherwise show signs of binding, and is based on the odometer being geared to the same input.

You can double check the above by taking the time to calculate the rpm required to drive the rear tire to a certain speed and see if the speedo (on the front wheel) agrees with that. You'll need to know the transmission ratios ( or at least the one you'll use to check in) , the sprockets ratio and the circumference of that rear tire and the rest is pretty easy. I can help if needed.

Thirdly, you could find a police radar check and ask if they'd check you at some speed below the posted while you hold it as steady as you can. All you can do is ask!

No matter what, at faster speeds, tires "grow" in diameter (and thus circumference) slightly.....heat, pressure and tire wear affect this slightly so high accuracy over time is not going to happen. Not too bad at all reading just a little fast.

 

[spyug]

Sparkss, You bring up a good point about their concern. I asked him and his answer was pretty cut and dry. You don't know what speed you are riding at period. You can't fight city hall can you.

I managed to get the fairing off and pulled the cable from the gauge and lubed it this morning. After lunch I'm going to check it against my son's GPS to see what I'm running.

Tomorrow, I'm going to go see my regular wrench ( who is back from vacation) and see what he says. I might have to get it into him but if I do it will likely be another week or two before I see it again as he is super busy. I guess I've been waiting long enough so another week or two isn't going to kill me.

I'll let you all know what transpires.

Cheers,
Spyug

 

[twistedwankel]

How would you go about checking accuracy short of having a radar gun?
I'm not sure now how to proceed.

Use mile markers and run at what you think is 60mph while checking your watch or get really accurate and use the stopwatch feature of your Timex. If accurate you should hit one minute exactly. Difference in either direction will give you the percentage of error as to fast or slow.

OR. Simply follow someone in a car at 60MPH and see what your speedo reads. If they are the same within 1 or 2 mph that's about all you can do for accuracy. Most all speedo will read a little fast brand new.

 

[Guest]

Simple Solution:

Remove the cluster, and take it back.

Motorcycles are not required to have any guages (at least in massachusetts). all that is for "informational purposes only" and not necessary.

Once it's "certified" (I still don't fully understand this as I have never taken a vehicle to a dealer for repairs) you can put the guages back on if you like.

 

[spyug]

I wish it were that simple but in Ontario for a mechanical fitness certificate, the motorcycle must be fitted as it came from the factory and all devices must function correctly. Some mechanics will turn a blind eye to some stuff but then you get others that are by the book. I have a by the book guy in this situation.

I didn't get a chance to test it against GPS yesterday so I'm planning on that for after supper today. If the speedo is still off I was thinking of going to a bicycle computer which I believe would satisfy them.

I'll let you know how it goes.

cheers,
Spyug.