Speedo ratio in speedo or sender?

[Guest]

Is the gearing for the speedo ratio in the speedo head or the front wheel sender, or both? In other words are all the speedo senders that look the same geared the same no matter what bike they came on with what size OE wheels? I'm starting to think about my next projext and I'm going to have to change the guages for sure since the new engine wont have a tach drive.

Thanks
/\/\ac

[JayH]

Doesn't your bike have a speedometer drive off of the left hand side of the front wheel? I would think as long as you keep the same front end on your bike it wouldn't matter which GS speedometer you hook up to it.

The best way to find out is to do some testing.

[earlfor]

Re: Speedo ratio in speedo or sender?

I believe the gearing in in the front wheel assembly. For a given assembly, it will only read correctly if it is mated to the same diameter rim.

Earl

Is the gearing for the speedo ratio in the speedo head or the front wheel sender, or both? In other words are all the speedo senders that look the same geared the same no matter what bike they came on with what size OE wheels? I'm starting to think about my next projext and I'm going to have to change the guages for sure since the new engine wont have a tach drive.

Thanks
/\/\ac

[Macmatic]

Well here is the thing, I'm going to be putting a GS700 engine in an '82 GS550 Katana frame with as yet unknown forks and gauge pod. Could be parts from four different bikes, or more, in the end.

So I think what I'm getting here is that the gearing in the speedo head units is all the same and the difference for varying wheel sizes is corrected at the wheel with different gearing in the speedo drive on the left side? Good... if thats the case chances are I can come up with something that works.

/\/\ac

[duaneage]

All of them are the same, even across Honda yamaha and suzuki.

[jonr]

Mac,

The tach is a much easier thing to replace. Aftermarket tachs from AutoMeter and others use the ignition coils as the source for the revs, not a mechanical line.

Not sure about the speedo since both the 700 and the 550 Katana are sort of specialty GS's.

-j

[Macmatic]

All of them are the same, even across Honda yamaha and suzuki.

All of which are the same, the speedo drive units on the wheel? Other brands too? ??? NOW ya tell me I could have shopped around more.... sheesh.

/\/\ac

[duaneage]

Walk through a motorcylce junkyard and take not of what is on the front wheels of different bikes. You can also check it by rotating the drive portion and counting the number of revolutions of the cable drive. I think 2.6 - 1 is the standard ratio but don't quote me..

I have a drive from a 82 850 on my 81 650. Works great. Unless the front wheel is a different size but then again the speedo could be calibrated for the wheel size, not the drive. Counting the revolutions is the best way to know and also specify what drive ratio your looking for when asking around.

[Macmatic]

Walk through a motorcylce junkyard and take not of what is on the front wheels of different bikes.

If I could find one I'd move there...

Okay... final revision. So I need to match the wheel and speedo head unit and the drive at the wheel is going to be the same ratio on most any bike. Right?

If I use...picking randomly....Bandit 600 front forks I need to find a gauge cluster with a speedo from a bike with the same relative diameter front tire or use the Bandit gauges. Makes sense.

/\/\ac

[SqDancerLynn1]

Go by the front wheel size 19" use one from 19" wheel ////// 17" use one from a 17" wheel

[JayH]

Go by the front wheel size 19" use one from 19" wheel ////// 17" use one from a 17" wheel

That makes it easy to understand.