USA MPH Speedo Question ??

[Foxfix]

USA / MPH Speedo Question ??

On a USA / MPH speedometer, the maximum MPH shown is 80 MPH.

There is a Needle Stop Post just after the 80MPH on the speedo face..........so what happens to the needle if you go past 80MPH ?

Does is ruin the needle or damage the inners ? ?

[warren3200gt]

No, the needle shaft is driven by a magnetic field, not a direct drive.
The needle drive and cable input have no direct contact with each other. Not a khi one but same principal.

[Foxfix]

Ta !

[gray]

I've seen photos of speedo faces from the USA with the needle severely bent in magazine articles back in the day

[BAFF1960]

Due to the original 160mph speedo running slow on my B2 I installed a US spec item ( cheap ) whilst I inspected and adjusted it.
I didn't have any issues with it after running at high speeds ( private roads only ) and it had excellent calibration compared to the larger range on the UK spec item.

[stusco]

Ive not tried mine over 80 mph yet so i don’t know if it will stop at 80 (gpz1100 a1) is there a fix if it does?

Mine doesn’t have a stop at 80 just a red 55

[Gray17]

Assume its the same principle on both speedometer and Tachometer, ie both driven by magnetic field, so cable roates as it should freely, the tacho needle on mine is fine up to 5000 revs then starts to jump about wildly until the revs settle back to 5000 or less, question is why.
If the inner as per diagram rotates and the outer which presumably is connected to the needle, with a hair spring to bring it back to zero. The faster it rotates the more the needle should move due to magnetic force, fully get the priciple, what i cant see is why or how the needle goes wild above 5k but settles back as normal below 5k.
Know its not a speedo but same principle surely applies.
I would think its damping fluid but its rock steady below you'd expect it the same at all revs. You may say just buy a new one, well this is a new one. Checked cable too its perfect as is the cam drive gear.

[warren3200gt]

Graham, those reproduction instruments are and were cheaply made rubbish compared to the oem instruments. I've just done a load of work on a mates (new to him) bike correcting all the errors on it which were due to it going through the "thorough" pre delivery workshop of a leading Z shop. They fitted repop instruments and regardless of engine speed the rev counter wouldn't go past 5k.

[Gray17]

Mmm Thanks for info sounds a lot like mine to be honest. My original one which is genuine i still have but it had no damping fluid so was bouncing all the time. As the case was slightly dented and the black not great bought new one thinking that would be better obv not! Not only that but its very slightly bigger too only 3mm or so but yoy can tell. Ill have to live with it as is now. Not that i go over 5k very often

[warren3200gt]

Put the original internal in the repop case and use the repop face. Refill the damper bowl whist it's apart.
Original internals, smart tidy visually.

[Gray17]

Thanks Warren thats def a possibility, although i still remember the issues i had with the trim rings last time, opening and re sealing. Alrhough as brand new may well not be as bad as the 40+ year old ones. I could always send original away but its already had new face and new glass too, its only the damping thats the issue, but as trim ring been apart and back together suspect if i opened again it will split.
What type of oil is in the damping pot, presumably fairly thick?
Thanks

[warren3200gt]

Believe it or not its 3 in 1 machine type oil. That's why anything stored anything but veticle the oil will have leaked out.

[BAFF1960]

The damper pot oil is extremely thick, otherwise it wouldn't add any damping ( drag ) to the needle shaft and leak out in a heart beat. I had issues with the 50 year old NOS speedo and tacho on my S2 a couple of years ago and was recommended this by people in the know.

[sweptail]

My speedo needle goes berserk above 5revs and not much better below. i have always thought that the damping oil had seeped out and could not be replaced. So, is it possible to fill up the tiny oil cylinder using this oil pictured? Tacho is not as bad as speedo, but still has its moments.
Tommy

[BAFF1960]

It is possible to refill the damper pots on tacho/speedos but is best left to someone who has experience in there overhaul as its very fiddly and correct quantity is important. Also you need to test and adjust for accuracy after reassembly. I've had a varied career in precision engineering and am confident in my abilities to tackle anything but not everybody can with success.