Hello All,

I found my way to your forum via a Grinnall Scorpion user group. 
I have a K1 powered Grinnall Scorpion 3 that I assembled back in 1997 (before the internet was such a big thing), used it a bit then struggled with several nuisance issues for which it was difficult to find good information & guidance, then work & family took over my life and the Scorpion languished in my garage until my son motivated me to get it back on the road last year. 
I realised then that the internet is a near-perfect resource for all of those hints & tips for solving issues with automotive gems that are long past end of production.  
I'm hoping to benefit from the wealth of knowledge here about the K Series engines and related peripherals used in the Scorpion (speedo calibration is one of my next tasks), and engage in some discussions - perhaps I can contribute a little based on my >20 years experience as a a gasoline engine management system engineer (cars only, though...) in one global vehicle manufacturer & one Japanese global Tier 1 supplier. 

Looking forward to engaging with the community...

Welcome MIini Hatchet. Your machine sounds interesting. I didn't know that Grinnal made a trike using the K engine. Many years ago I sold Grinnal the BMW C1200 Cruiser I then owned which they converted to a trike. I'm interested in a trike now as I'm suffering from age issues. It may not be your cheapest solution but I've fitted an Acewell after market Speedo unit (I can hear a loud sigh from the purists on this site) that works a treat on all functions on my K1100. Nice retro styling in my opinion. Can you show us any pics of your trike?

Hello Glyn,

The Scorpion 3 is not a "trike" per se (which in my understanding usually refers to single front wheel, two at the back, at least in Grinnall's case).
However, it is classed a a tricycle, having a space frame body with two front wheels and the K series powertrain complete (engine, transmission, prop shaft & final drive) at the back.  You can see some pictures and information on the Wikipedia page: https://en.wikipedia.org/wiki/Grinnall_Scorpion_III

I have seen a few Scorpions, there are a few of them over here too and one quite near me.

Lovely motors, in most cases quite easy to work on.

I wonder though how it got to be K1 powered, an expensive route seeing as the K1100 was also a fit and so was the 16 valve K100 engine which is same as the K1 anyway.

As for the speedo, you can use K1/K100/K1100 unit, the speed sensor is on the rear final drive. All standard K parts.

They can be recalibrated depending on your rear wheel diameter. I am not sure what the original rear wheel size was on K1, but it would be either 17 or more likely 18 inch. At a guess I am thinking 160/60/18 but you will need others to verify. The K1100 used the same speedo units whether the rear was 160/60/18 or 140/80/17 as the rolling diameters were actually quite close. The plastic nylon gears inside do go wrong but there are fixes for them.

I'm pretty sure I've seen the K100 version and it's still an inline fitting. Ah! - Here we go.

https://tricyclecars.1fr1.net/t2186-grinnall-k100-bmw-linas-montlhery-septembre-2017

hello Mini Hatchet

Welcome to the forum!

Hello!

I found the forum instructions on how to share photos, so I thought I would show you my Grinnall Scorpion...
 
  

I can see how that'd put a grin on all's face.

Two Wheels Better wrote:I can see how that'd put a grin on all's face.

Pun-tastic!

Interesting that it's made from a K1 since the K100RS4V is the same bike under the Tupperware and cost less.

But the yellow K1 drive train looks great with blue body paint and a K1 does have taller final drive gearing than a K100RS4V. (K1 is 2.75, K100RS4V is 2.82)

Very nice road toy!

Hi,

to our community!


Bernie