Speedo Ratio - After Market Options?

[Guest]

Hey guys,

Trying to get my head around speedo ratios as I may need to go back to an after market mechanical speedo.

As best I can tell my GS450 is 2240:60mph or 1400:60kph for the speedo ratio. Does that seem right? Been searching here and found little to validate that... possibly my searching isn't ideal!

Do I simply need to reference this ratio when evaluating after market speedos? Aside from the obvious such as thread size for the cable of course.

This is the one I'm contemplating at present: https://www.thirdgear.com.au/cafe-racer-led-mini-speedometer-black/

I've yet to measure the speedo drive cable etc. as I've gotta see if I still have my old one at home or not.

 

[Guest]

Ok I think this thread answers my question... and of course I found it after I posted

https://www.thegsresources.com/_for...edo-drive-gear-ratios&highlight=speedo+thread

So providing 2240:60mph is equivalent to 1400:60kph then I'm good.

 

[Rob S.]

As best I can tell my GS450 is 2240:60mph...

That seems rather low as the original review of my '82 11E says 3811 rpm at 60 mph. In fact, the tach actually shows 4K or more at 60.

Unless I'm misunderstanding something, which happens every day.

 

[Guest]

speedo ratio, not tach, Rob.

 

[Rob S.]

speedo ratio, not tach, Rob.

Sounded a bit torquey for a 450!

 

[Sandy]

Sounded a bit torquey for a 450!

It's not.engine rpm it's speedo cable rpm.

 

[Gorminrider]

my GS450 is 2240:60mph....

yes they are very close to the same ratio...
2240/(60*1.606kph)=23.246 and compare to 1400/60kph=23.333333...
Tire sizes an inch or so diameter is about 5% I think so you will want to check it per real life with a gps and/or odometer check.
Many Japanese bikes of the era use the same-same maker (Denso?)
Larger gauges are more accurate and easier to see.

The ones you are looking at give me a twinge- I bought a very similar (clone?) for 15$ on ebay and it was junk so get a solid guarantee.

 

[Guest]

Ok cool thanks for the clarification! And yes, we're definitely talking cable rotations here... the 450 is most definitely not that torquey

I'm actually looking at a different speedo now from a custom place that is more local to me: http://mostynindustries.com.au/product/speedo-60mm-black-with-warning-lights/

I've done some research and the place selling this particular speedo reckon it's a good quality item. I definitely need it to be so as I ride in all weather conditions 365 days a year. I've had a look at many cheapo eBay ones and this one seems to be a bit different in as much as most read 220kph but this one goes to 140, bit hard to tell other than that if it's any different. I intend to go pick it up which means I can talk to them about it also and see what they say. I probably won't be able to get there until Friday though which is a little annoying.

 

[Gorminrider]

good-oh, Pete..by the way, another irritating thing to check-and it's personal taste but my Clone had eye-burning led indicator lights...wonderful tech but not really pleasant at night especially the hi-beam which I use at night hereabouts. ... but yes! they are good in the day... and in the city lights too. Still, I thought it'd be something to know for yourself versus originals.... I know what a keener you are and you should have the "right-stuff"!

and, to repeat,I wouldn't recommend a "MINI" gauge it's just too small -I just have to think too much deciding how obvious it is within 20kmh.but I never got used to it either.......so I'd probably favour a digital LCD readout (daylight viewable is the diff) if I wanted a small gauge

 

[Guest]

I hear ya', and I actually have that issue with the dash on my Kat which I have yet to resolve. I used bright LED's for the day, but have left them too bright for night riding which is fine for all except the high beam LED and I'll do something about a larger resistor or something along those lines at some point.

I think 60mm is going to be ok for me providing there's good clarity, that's why I definitely need to check it out in person before purchasing. I can't see me getting down there any earlier than Friday at this point unfortunately, too many meetings at work this week.

The alternative of course is a second hand stock speedo off something else, but for what I need/want and the available lack of budget at the moment they've proven ridiculously expensive locally unless I go for similar vintage gauges, and they're likely to have me back guessing speed again due to wavering needles, which is why I got rid of my stock gauges in the first place.

 

[Gorminrider]

Yes, I believe you are right- Another clapped-out speedo- who needs that?

I'm presently thinking that in the end, the steel magnet that operates the needle will lose its field, irrespective of low kilometers..banging around in a parts box is not a happy place for them long term and then there's the air-corrosion of 40 years...

I struggle on with the old ones to maintain the "original" status but it'll naturally get more difficult to do without some "deep" tinkering.

LEDS' brightness can be tricky to control..they are voltage sensitive, and will not conduct current below a certain voltage level ( incandescents are more clearly "resistive" and easier..rheostatic, dimmable...) so setting tuning a lower brightness for an led might be inside the "looseness" of your overall system's regulation. It can be pretty fine regulation...* I'd suggest trying a cover lense siliconed? on for easy no-destructive removeall, some dulling tape as being much simpler!

* a good voltage regulation package can be custom made in the shop but it needs a bit of tinkering....and it'd be a little cluster lump added on the circuit ..inside the headlight or under the gauge's cover..

 

[Guest]

Yeah I got rid of the stock gauges due to the needle being all over the shop despite lubing the cable and the speedo itself as best I could, just couldn't get it to read a stable speed. I thought a GS500 speedo might be doable but they don't go cheap around here either.

As for the bright LED's, a mate has sent me a schematic using a voltage regulator as a current control device to drive LED's but I haven't gotten my brain around how I could incorporate it in the Kat dash just yet. That's a future Pete problem at the moment

I'm not stressed about original at all, I like a bit of a custom touch but when it comes to a speedo, it's gotta be right as that's license preservation right there, especially on the commute!

For the 450 I found a fella I used to ride with about 20 years ago is selling a brand new speedo on eBay for about half price so I'm going to pick it up this arvo after work. Apparently POSH brand is quality Japanese stuff from everything I've seen so far. I got my mechanical speedo drive and cable all together and operational last night so it should be good to go pretty soon.


https://www.ebay.com.au/itm/Posh-Sp...e=STRK:MEBIDX:IT&_trksid=p2057872.m2748.l2649