Motoscrubs.com

Hi All,

I have this speedo on my 68 MK3D. I think I now have the right one for it, but what bikes is this right for?

Kev

" I have this speedo on my 68 MK3D.
but what bikes is this right for? "

____ This model/version is one of the rarest speedo-types,, usually when I've ever seen this fairly common style, it was most always just a 80-MPH version (as for 160-MonzaJr).
I believe this 100-MPH version was originally used mainly on 1966 n-c 250-Monza & many 350-Sebring models, (but not totally positive about it). _ It's been so very long since I've seen totally original Monza & Sebring models that I'm just no longer positive which version -(80 or 100) was originally on which models... I am sure that I've seen (back in the mid-late '60s), the 80MPH-version on some used 250-MONZAs (which all ought not have been old & used enough to have had their original speedo-units replaced!), and most (but not all) used 1966 350-SEBRINGs I've seen had this same 100MPH-version.
__ The white-paint (displaying the number-digits) on the inside of the glass is well known to peel-off inside, and thus leave the viewer to have to estimate the speed which the pointer-needle seems it would mean to indicate, (with the use of whatever speed-numbers are still left showing on the glass).
__ This shown unit has more milage (over 20k!) registered than any other I've ever personally seen on a Duke ! _ (The second highest was my own, with nearly 17-thousand.) _ My own experience with this model/type of speedo has seemed to indicate that they last/run longer than the other model-types of stock speedo-units.
Also, despite the indicated high use, this one appears to still be in pretty-good condition.
__ I've also found that this model-type is fairly accurate at it's indicated-speed
so long as the engine is not overly buzzing-away... Cuz whenever the motor-vibration is moderately-high, the needle-pointer is then buzzed all over the dial ! _ (As is also the case with all other stock model-types of speedo-units.)
Whenever that disconcerting situation is occurring, ya can just pull-in the clutch & shut-down the throttle (to let the revs fall to idle), and then the needle-pointer will quickly settle-down and smoothly indicate your real speed (within about 5%, with a stock front-tire).
____ I'm re-posting the posted pic so that it can now also be completely seen in it's entirety here (without first downloading). _ (I don't even know how others manage to post their pix so that their whole submitted image is not fully displayed.)


DUKE-Cheers,
DCT-Bob

" testing attachment process "

____ I see that now machten... you've now successfully managed to get your picture posted without any portion cut off from it !


" I think I now have the right one for it, "

____ So then how about next posting a picture of your intended replacement speedo-model ?


Hopeful-Cheers,
-Bob

Thanks Bob.

__ I've also found that this model-type is fairly accurate at it's indicated-speed
so long as the engine is not overly buzzing-away... Cuz whenever the motor-vibration is moderately-high, the needle-pointer is then buzzed all over the dial !

Yep - as you say, it bounces around a little with a bit of buzzing. I compared its reading with a GPS last week and 62mph is reading as about 75mph, but I haven't explored the drive gear matching yet. (Pity... I was well impressed with the bike's 0-60 performance! )

__ This shown unit has more milage (over 20k!) registered than any other I've ever personally seen on a Duke ! _ (The second highest was my own, with nearly 17-thousand.) _

Interesting! I didn't think anything of the milage, having come from a Duc twins background. I guess I'm suprised it's that uncommon.

I've got the correct speedo to test and fit so although I prefer the appearance of this one, if the other speedo tests OK, I'll fit that one and check it against the GPS.

Kev

So then how about next posting a picture of your intended replacement speedo-model ?

It's the same as this one. I think it's the right one.

Edit: As i said earlier, I prefer the white faced one - looks the part with the white face veglia tacho.

Kev

" as you say, it bounces around a little with a bit of buzzing. I compared its reading with a GPS last week and 62mph is reading as about 75mph, "

____ Perhaps your current front-tire is smaller than original ?
Also, it's possible for the vibration-rate to be just-right so as to HOLD the needle-pointer just above or just below that which it actually intends to be pointing towards, so even when you think it's steady, it still possibly pays to kill the engine-revs and then see if the MPH-indication remains the same, (just before ya next begin loosing your set test-run speed).
And when your needle-pointer is getting buzzed-around, of course be sure to do the same, before deciding how far off your meter's true reading actually is. - (I'm sure it's not over 10%, at least compared to the speedometers within the cars I had compared against.)


" I guess I'm suprised it's that uncommon. "

____ Pretty-much all of the junkie speedo-units which came stock on our old DUKEs would break-down one way or another before 13k could be counted onto them !


" I've got the correct speedo to test and fit
if the other speedo tests OK, I'll fit that one and check it against the GPS. "

____ That will be an interesting & welcome revelation to be posted here !
__ I believe the stock speedo-unit for the Mk3 should read 150-MPH, and it's (understandably) even less accurate ! _ (I always thought it was stupid to have them with dials which read over 120!)

____ So how about also posting a picture of your rare -(1968) Mark-3 (non 'D' ?) ?


DUKE-Cheers,
-Bob

____ It seems that my usual slow posting-method has my posts falling out of proper order with your's here Kev.


" It's the same as this one. "

____ I see that now... It does appear to be the correct speedo-model for a w-c Mark-3 ('D' or not).


" I prefer the white faced one "

____ So do I, cuz it's more readable !
You can look-forward to this other type of indicator getting buzzed-around to over-cover even more MPH-range.
__ I see that this particular unit (seen in your last picture) has about 2-thousand less tick-overs than most rack-up before they begin to stop ticking. - (My guess is that this one will likely not make it past the 6k+ average break-down odometer-reading for this model-type. - Sorry to say!)


Dukaddy-DUKEs,
-Bob

Perhaps your current front-tire is smaller than original ?

Good point - I didn't check that and I should know better as I choose to run my 750 Sport with a 90 aspect ratio tyre which affects the speedo a small amount. The tyre looked "right". In retrospect, probably more accurate to say that it didn't look "wrong" enough to attract my attention. I'll check tonight.

So how about also posting a picture of your rare -(1968) Mark-3 (non 'D' ?) ?

It's a "D". I posted in the photos section last week, but I've fixed the "attachment" thing for the singles photos now.

http://www.motoscrubs.com/forum/viewtopic.php?f=11&t=427

I see that this particular unit in your picture has about 2-thousand less tick-overs than most rack-up before they begin to stop ticking. - (My guess is that this one will likely not make it past the 6k+ average break-down milage. - Sorry to say!)

That's not the actual speedo, just a pic I found on the net. I don't have the unit near me and don't remember the odometer reading. Knowing my luck, probably 5,999. I tested it on a drill and the needle moved up and down with revs, but no idea if the calibration is anywhere near right until I fit it. Maybe I'll get lucky!


Kev

" The tyre looked "right". "

____ The original front tire-size was 2.75 x 18 and (if my memory still serves me at this moment), the outer-diameter of the mounted tire is about 78-inches.


" I tested it on a drill and the needle moved up and down with revs "

____ Likely still under 6k then... Let us know, after you find-out it's milage-reading.


Hopeful-Cheers,
-Bob

Just a quick update...

The speedo I have reads 13652 on the odo. The tyre is correct, so there is some issue with callibration on the existing speedo. I calibrated drill speed against wheel revoloutions through the drive gear and the replacement tested as close to spot on as i can reasonably expect. +/- 2 %. (Bob, you might have to rethink life time of these things!!! How am I doing if we add up the odo's of working units and average them? Do I get a prize?)

Progress on in situ testing is halted as I went to check and adjust valve shimming and as I was unfamiliar with the condition took the opportunity to remove and dismantle the head. I discovered badly worn opener rockers and cam. Probably due to a previous owner having no idea about valve shimming. Getting a bit off topic now, I know. Just wanted to outline why no progress. I'll come back to this after correcting the top end and testing the speedo in anger.




Kev