Skorpion Tacho replacement and Gearlever swapout.

[Linegeist]

Two issues here chaps.

1. THE TACHOMETER THAT DOESN'T
It seems I have the standard Skorpion tacho problem in that it doesn't actually 'tach' ... well, not in any meaningful sense. The needle sort've flops around the dial like a stranded fish on Ecstasy. The shaft bearing's worn out, going by the crazy gyrations of the needle, and the whole thing's about as much use as a bacon sandwich at a bar mitzvah.

I've been looking around EBay for a replacement. Strewth! You'd think I was looking for something illegal!! You can search for "Tacho" ..... (a zillion hits - all for 4-6-8 cylinder engines) but you try refining the search with anything like "Single cylinder" or "Motorcycle" and the search engine treats you like a leper......

Obviously, some of you learned gentlemen have solved this problem already, so what's the standard fix? I'd like stay with an analogue dial, although if I have to replace the MB unit with a smaller tacho then I'll mount a 2" temp gauge in the space freed up. I'm also happy to go with a cable drive unit if necessary - I gather there's a blanking plate on the Yam motor that houses the necessary takeoff point. What are the hot-swap options available to me?

2. TOP GEARCHANGE MOD FROM BILL JURGENSON
I tried Bill Jurgenson's gearlever swapout for an XT660 part at the weekend(see his website), ditching the MZ rearset linkage fitted as standard, and fitting the replacement lever direct to the selector shaft pointing rearwards, reversing the gear selection to 1-up (for first gear) and 4-down.

Total swap time = 15 minutes and what a difference! The box feels slicker, no more vague hunting for neutral at lights and no more missed changes, and the box snicks through the gears with nothing more than a gentle prod with the toe making for some very fast cog-swapping on the move (and making the most of that wonderful classic burble from the exhaust on the overrun).

An excellent modification that was well worth the cost of the Yamaha gear lever. Thanks Bill!

[Nils D]

According to your symptoms, it sounds as if there is a electric component inside the tachometer that has come loose. Open it carefully and see if there isn't somthing that could be resoldered.
It's discussed in the end of this thread:

http://www.mzriders.com/viewtopic.php?f=20&t=1688&p=12348&hilit=tachometer#p12348

It will still not be a perfect tachometer, but it will not be hysterical.

Nils

[Bill Jurgenson]

Very happy to hear that you immediately came to grips with the reversed lever and, like almost everyone who has tried my bikes, found it indeed much better.
Like I must a siad too many times and you found out, you shift literally with your big toe.

The MMB tach is crap alright. But beware, later Skorpions have newer MMB model tach which is better BUT it uses the SZR CDI (orange label) and does not work with older Skorpions. Likeweise MM is now ofering what is clamed to be a good tach but it, again does not work with the XTZ CDI. All three possible CDIs work as far as the bike is concerned and the OEM MMB Tach works too - if it works - but only the SZR box works with the later instruments.
So not worth it to investigate: the older tach is crap, the newer ones cost over 100€ new and you need a different box as well, not to had for less than 50€ used at eBay and new something like 250,--
Same goes for the SZR tach which you can use IF you use the SZR CDI but you'll have to pull in a wire from the CDI to run it since the early Skorpion harness does not wire to this pin. BTW, the same problem with the newer MMB instruments as well.

You can use a mechanical tach , e.g. SR or SRX but at the bottom line that will cost as much or more than the Scitsu.
The bevel drive off the cam costs new around 90€. Then you need a tach and the drive cable as well.
I used an SRX tach when I was running a magneto, because that magneto would not support an electronic tach.

cockpit.jpg (68.2 KiB) Viewed 6643 times

Having basically the same engine, the SRX tach has an ideal range and red line.

Your best buy for the money is the Scitsu.
You need the third one down on the list labeled red, obviously with the 10000rpm scale.
These are good and dependable and can be serviced as well.

I use a Kroeber/Pitsch,

Pitsch.jpg (69.82 KiB) Viewed 6642 times

very fine and always servicable even after 20 years if need be but I haven't yet.
More expensive than the Scitsu.
Both these run off the minus pin of the coil.

Getting into real money, there are several choices of combined instruments with round analoge tachs and digital speedos.
extremely good: WMD
then Stack
or Motogadget

or you can go whole hog for something really high tech (and again servicable!) like an instrument from AIM.

AIM.jpg (69.32 KiB) Viewed 6642 times

This Mychron 4 2T is the low-level entrance model costing around 450€ once you have all the bells as whistles that you need.
-Analoge and digital tach - the RPM range can set as desired
-shift flasher - can be set as desired
-two temperature sensors defined as necessary, each with a freely definable warning light
-voltage
-laptimer
-USB readout of ALL the data
etc etc etc
You see it here mounted on a racing Skorpion I built up for a friend. I can highly recommend it. After his first serious outing the friend is full of praise as well.
The [Mychron 3 ca do much more including speedo but also costs much more.
Like I said, this is getting real expensive. You can buy a ratty Skorpion for what the Mychron 3 with all the bells and whistles costs.

[Linegeist]

Wow! A whole shedload of information!!

Having now carefully read all your excellent advice, and gone away to think about it/look up the various links, I'm minded to go down the mechanical drive route with the takeoff from the camshaft.

The reason for this is that I'm trying to replicate the Norton cafe racer look of the 1950's with my Skorpion, and the electronic tach's (while very nice) would not be as 'in period' as a cable driven unit.

Thanks to your information Bill, I now know that the parts are available and what to look for. I'm going to scour the internet for somebody breaking an SR or on SRX.

Yet again I seem to owe you a Bier or Zwei!

[handsomejackuk]

checkout the trail tech vapor, great bit of kit Rodge is using oe and hat has lads of features, shift change light, rev counter, temp guage, service indicator etc.etc it only costs £75.......

Worth a look at if yah wanna go digital..

Phone trailtech u.k. they are real helpful

Jak

[Nils D]

The MMB tach is crap alright. But beware, later Skorpions have newer MMB model tach which is better BUT it uses the SZR CDI (orange label) and does not work with older Skorpions. Likeweise MM is now ofering what is clamed to be a good tach but it, again does not work with the XTZ CDI. All three possible CDIs work as far as the bike is concerned and the OEM MMB Tach works too - if it works - but only the SZR box works with the later instruments.
So not worth it to investigate: the older tach is crap, the newer ones cost over 100€ new and you need a different box as well, not to had for less than 50€ used at eBay and new something like 250,--
Same goes for the SZR tach which you can use IF you use the SZR CDI but you'll have to pull in a wire from the CDI to run it since the early Skorpion harness does not wire to this pin. BTW, the same problem with the newer MMB instruments as well.

Bill,

what's the difference between the old CDI and the SZR one?
A different way of sending the signal to the tachometer?

I have a 96 Taveller and there is hardly any hope left for the tachometer. But instead of having to get a totally new instrument-cluster, I've found a firm that renovates/rebuilds instruments and I'm thinking of letting them put a new interior in to the tachometer. And I want to make sure it will work with the old CDI.

[den]

i got one of these from fleabay for about a tenner/ xt 600/500 tacho drive unit,which fits straight on
gallery/pic.php?mode=large&pic_id=623

i got mechanicle tacho (universal tacho) 4 to 1 ratio,ideally topping out at 8 thou rpm for
another tenner from fleabay.see gallery photo. i suppose any make with the correct ratio will do ,i like bmw ones

The cable i made up from

drive side was a xt600 so it fits the drive unit and clock side was anything i had lying around, to get the length the outer
cable had to be measured and spliced where ther were little or no bend and refitted with i bit of
ally tubing and some shrink rap,( use two halves to make required length)
The inner cable was a " universal speedo cable repair kit" this is the inner wire thats 1.5 mtrs long and you custom fit
the square end once its sized up to the new length of the outer cable.

[hb7]

I have one of these pro cycle autometer and it's rock steady....on my 1998 Skorpion.
Plus it fits in the same hole......

I have a collection of 6 MMB tachs, they all bounce. I replaced the electrolytic capacitors and saw no improvement.
They appear to be well made, but the repair they need escapes me.

http://www.ebay.com/itm/Autometer-8k-Tach-Tachometer-3-8-White-Chr-3-3-8-Dia-/320753460339?hash=item4aae656473&item=320753460339&pt=Motorcycles_Parts_Accessories&vxp=mtr

[Nils D]

My tachometer has been to the instrument-repair-shop.
When he tested the tachometer in the workshop it worked as it should.
(It's tuned, synchronized as if it's on a two-cylinder motorcycle. I'm not sure what it means, I guess it has to do with signal from the CDI-box, that it should be hard to give steady signal from something on low revs.)
I guess the MMB-tachometer has hard to handle the vibrations on the motorcycle, something that could be difficult to simulate in the workshop.
He could have replaced the electronics, but he did just go over all the soldering.
I have not tested it on the bike yet, it's still to cold, but I'm not overly optimistic.
Or maybe it's somewhere else in the wire-harnes that there is an intermittent connection, or the CDI is not the way it should…

[hb7]

I wrote MMB and they said the MZ Skorp has too much vibration.
They punted and blamed the bike for the bouncy tach.
Nils : I will be interested to see ....if it is fixed.
The other theory is that the MMB tach is very sensitive to RF noise.
Change the Tach signal wire out to a shielded coax grounded wire.
( haven't done it yet) I gave up on MMB.

On the other hand the Asahi/Suzuki tachs on the Skorps have no issues at all with RF.

[Nils D]

Finally I've taken my bike out of winter-storage, and seen my reworked tachometer i action. And it works as it should.
Of course I'm happy that it behaves as an tachometer should do, but I'm not sure why, maybe it's just by having an expert going over it with the soldering-pen.
Anyhow, for 100€ I have a working tachometer, but I would not be surprised if it will become hysterical again…

[mincehead]

Why are folk so obsessed with it?, I never look at mine and wouldn`t miss it even if it were not there apart from the hole it would leave. I find watching the road ahead to be paramount when riding a motorcycle (on the road) not watching a guage that just might be lying to you anyway.
Skorps were built to a budget, some things are not `up there` with exotica but the overall package is far better than many of the all singing and dancing plastic rockets I love to leave in my wake on my favourite twisties.

[Skorpion]

Why are folk so obsessed with it?, I never look at mine and wouldn't miss it even if it were not there apart from the hole it would leave. I find watching the road ahead to be paramount when riding a motorcycle (on the road) not watching a gauge that just might be lying to you anyway.

Yes you are probably right.
Others like their tach to work as intended as its such a good looking unit, luckily mine's not too bad, only slightly telling porkies

[den]

Why are folk so obsessed with it?, I never look at mine and wouldn`t miss it even if it were not there apart from the hole it would leave. I find watching the road ahead to be paramount when riding a motorcycle (on the road) not watching a guage that just might be lying to you anyway.
Skorps were built to a budget, some things are not `up there` with exotica but the overall package is far better than many of the all singing and dancing plastic rockets I love to leave in my wake on my favourite twisties.

Ill tell you why i was obsessed with it , I had been riding two strokes (crm250) for years and my brain got used to the high rev range,Then suddenly jumping on a big 660 single thumper i found it very hard to get used to ,As soon as i put the rev counter on life go much easier , i have learned what the engine sounds like when its at the optimum rpm to change gear,soon enough ill be able to ignore it and listen to the heart beat of the engine again,So there you have it , ,I got the rev counter to learn the relation between engine/exhaust note and gear change timing