Speedometer inaccuracy

[Dales venture]

Hi,

From UK member. I'm having problems with speedometer on my 92' XVZ1300. Odometer works okay and the bike has only done 14000 miles.

It's reading very high (40+ mph on the clock when actual speed is more like 30mph).

Before I start dismantling everything, does anyone know where the problem might lie?

Is it likely to be the clock mechanism, the cable or the gear hub?

Thanks guys.

Blake

[Marcarl]

If you had problems in the wheel gear or the cable the speedo would jump a lot. I have not had the pleasure to tear into the clock mechanism, but that is where i would go looking to see what can be seen.

[VentureFar]

Speedo reads 6mph to high on any speed over 40 on my 2007 2nd gen. I use the speed read out on my Gps and never look at my speedo.

VentureFar...

 

 

Sent from my iPhone using Tapatalk

[saddlebum]

My 1st question would be does the bike have the proper size tire on it or does it have an undersized tire and rim. The smaller overall diameter of an undersized tire and rim will cause the speedo to indicate a faster speed than what the bike is going. In this case the odometer would be out as well indicating more miles added up than what is actually covered.

 

On the other hand if the odometer is accurate but only the speedometer is off than the problem is probably in the head and you may have to replace the head. or as mentioned earlier rely on a gps. You could try getting into the head and see if you can repair or recalibrate it by adding tension to the spring in the head but that would be a real pain and lots of trial and error.

 

The speedometer on that is as you are aware is cable driven directly from the from wheel. The cable then drives a shaft that has a rotating magnetic disk on the opposite end which spins inside a small metal bowl. This bowl is attached to one end of a small shaft. The speedo needle is attached to the other end. In the middle of this small shaft is a very small clock spring. As the magnetic disk spins inside the magnetic bowel the bowl begins to rotated against the force of the spring. The faster the disk spins the more force created to overpower the spring and the higher the needle climbs up scale. As the bike slows down so does the speed of the rotating disc allowing the spring to overpower the magnetic force and bring the needle back down. If the spring gets weaker or if it has been tampered with it changes the balance between clock spring and the rotating magnet. In other words the weaker the spring gets the higher above actual road speed the speedometer will read. You could try bending the tab to which the free end of the spring is attached to increase spring tension but this could be hours upon hours of frustrating trial and error. Answer try to find another cluster or speedo head.

Edited May 26, 2020 by saddlebum

[WRIDR]

Hate to bring this up when you're already getting great advice.

 

However... our local Dealer here in Eastern Ontario, Canada - after serious grilling - confessed Ma Yammy deliberately rigs their Speedos to read 6-10% high. Not sure why, but suspect it's related to lawsuits from Folks driving too fast?

 

Maybe that's playing a part of the issue you're experiencing?

 

Rgds, WRIDR

[Dales venture]

Thanks for the advice guys.

The front tire is new and is standard size as per manual. Rim is standard.

Like you said, I think the problem lies in the clock end of things. The speed has been inaccurate since I bought the bike last year so I think sometime in the past someone may have put a magnet too close to the speedo itself causing disruption of the internals.

I wouldn't mind if it only read 10% out but when it's over 25% it's a bit much.

I wish I could post a picture on here but for some reason the page won't let me attach.

Cheers.

[Freebird]

There is no reason that you can't attach a picture. What size is it? It needs to be resized no larger than 1024 x 768 and 200,000 bytes.

[Marcarl]

If I remember correctly, 2nd gens have the speedo issue, where 1st gens generally did not. My 85 was close enough to be spot-on.

[Karaboo]

My 1990 is 2mph off no matter the speed. So calibration is good, but needle position is off a little. Odometer is perfect.

 

Sent from my LM-V405 using Tapatalk

[saddlebum]

The odometer is directly gear driven, by a small set of worm and spur gears on the speedometer input shaft just before the magnetic end, while the speedometer is magnetically driven countered by clock spring tension. So as per my previous description if the odometer is accurate but the needle is not than the fault lies within the balance between the force of magnetic drive and the tension of the clock spring. In which case the only and simplest fix is another speedometer head. Unless you have a whole lot of patience and tenacity and want to fiddle with the spring tension to try and get it right.

 

BTW here is a little interesting point I noticed, regarding the difference in road speed between the speedometer and that indicated by GPS. When driving in Ontario, I have noticed the speedometer on my truck versus the GPS to be within 0 to 1 Km of each other. When driving in Nova Scotia with the same truck and GPS the difference is close to 4 km per hour. Something worth thinking about when comparing speedometer to GPS.

[Dales venture]

Just wanted to say a big thanks to all you guys who offered advice re the speedo inaccuracy. Especially Saddlebum!!

Yesterday I took off the clocks, removed the speedo and bent the metal tab holding the spring slightly. After 5 attempts of testing and resetting, BINGO!!

The clock is accurate to within 1 mph!! Basically what the clock shows is the speed I'm doing. Yes it is fiddly but well worth it in the end and at least the odometer is the same (rather than having to buy another clock with higher mileage).

Really pleased when I hit the right tension in the spring.

Thanks again.

Blake (UK)

Edited May 26, 2020 by Dales venture

[saddlebum]

Just wanted to say a big thanks to all you guys who offered advice re the speedo inaccuracy. Especially Saddlebum!!

Yesterday I took off the clocks, removed the speedo and bent the metal tab holding the spring slightly. After 5 attempts of testing and resetting, BINGO!!

The clock is accurate to within 1 mph!! Basically what the clock shows is the speed I'm doing. Yes it is fiddly but well worth it in the end and at least the odometer is the same (rather than having to buy another clock with higher mileage).

Really pleased when I hit the right tension in the spring.

Thanks again.

Blake (UK)

I am glad we were able to help. I gotta say though, boy have you got patience!

[Dales venture]

img_20200521_163002

[Marcarl]

Glad you got it to work the way it should and thanks to @saddlebum for being a big help,,as he usually is.