Just registered. Thanks for acceptance.
Not quite up to full bike status as I've only got an engine.
I would like to get it running before I fit it.
So my enquires to come will be mainly based on setting up a test bed first.
Looks like I have a problem already as I have an incompatible wiring loom plug. It won't fit into the computer unit that's for sure.

Welcome!

Looking forward to your build.

Marvin M wrote:Just registered. Thanks for acceptance.
Not quite up to full bike status as I've only got an engine.
I would like to get it running before I fit it.
So my enquires to come will be mainly based on setting up a test bed first.
Looks like I have a problem already as I have an incompatible wiring loom plug. It won't fit into the computer unit that's for sure.

Welcome on board too.

Now when you say 'the computer unit' there are two and you may have one, that is if its an 8 valve engine....Both are needed. One is located under the seat [if you had a full bike and is about 6 inches square and one inch thick. Best use imperial since you might officially be non metric in a few weeks. This one is the Fuel Injection Control Unit or FICU. The second one is located under the headstock at the front of the tank and is the Ignition Control Unit [ICU].

Post up the engine numbers as that will give the week and year of manufacture as well as engine type. Plate is on the right hand side rear of the oil filler plug and down below it.

On second thoughts do that first as the 16 valve has a different system with only one computer.

To get it running on a bench you may need clocks as well but there are some on the forum who will know how to get around this.

So, do you have a 'rest of bike' to fit the engine to?

Great to see such swift replies.
Thanks for that. The engine is a K75. I got a job lot deal from someone who I know broke up 2 of them.
It was a while ago now so I doubt he will have the right bits. Can't really get my head round why the unit that won't accept the plug TBH. Did they do a multi valve version for the 3 cylinder engine ?

K75 is 2 valves per cylinder only. These all have the ICU and FICU. I suspect you have one of the two. If you are missing some they can be got easily.

The ICU FICU and coils do not interchange with any other K.

Getting it to run on the bench will take some work.

I have both units. One has mated up with its plug. Not having the bike then here is a link of the unit that's fine.
This is the unit that won't plug in.

Welcome Marvin

One heck of a project ...starting with just an engine! If you end up with a running cafe racer, then you'll be applauded (as opposed to those that start with a decent bike and strip her down into a cafe job). If you end up with a reconstructed running K75 then it'll be a standing ovation!

I was thinking that perhaps you were trying to plug the FICU (the bigger smooth silver one) into the ABS plug on your partial wiring loom (it looks very similar to the FCIU plug), but I'm not sure that K75s have ABS. I suppose it is possible that you have a loom from a K100LT(ABS) though....

I think you will also need the instrument console to be able to run the engine, but as Olaf says, there will be other wiser people hereabouts that may be able to tell you how to do without.

Anyway, enjoy the project

Marvin M wrote:I have both units. One has mated up with its plug. Not having the bike then here is a link of the unit that's fine.
This is the unit that won't plug in.

Top one is the ICU.

Bottom one is the FICU and clearly marked 3 cylinder.

Now I also have an ABS unit which looks similar to the FICU and the plugs look very alike, even the pins look identically positioned. But you don't need this to run the engine. Some K75 have ABS as Paul has said so wise to make a check that you have tried to mate the correct plug and unit. The plug to FICU connection sort of goes in head first....

This is a serious challenge......

Well I like a challenge. Just hope this works out.
You can give yourselves a pat on the back as I've just been into the garage on being given the information about partial wiring looms and the ABS plug similarities.
The engine is still holding on to that part of the copper spaghetti and plugged right in.
Most of what I was fiddling with is in a box of bits in the spare room. ( tis what spare rooms are for after all. Beds are so overrated lol)
So it looks like I now need to read up on the successful threads with juicy information on how to trick this BMW super computer to ignore as many redundant unconnected bits as possible. Any useful shortcuts to them greatly appreciated

I wouldn't worry about getting it running. If it is a K75 then your chances are about 99.9% that it will.

I had a spare K75 engine that I got with some other misc. parts sitting in my basement for lord knows how many years. I just assumed it would run and built a bike around it.

Started as this:




Ended up as this:




How I did it:

http://www.kbikeparts.com/classickbikes.com/ckb/1.my.k.bikes/10_K75F/k75f.3.build.htm


BUT, I have lots of parts around and know these bikes pretty dang well.


For all the parts you'll need to dig up($$$) and learning involved, my recommendation would be that you find a parts K75 to use as a donor bike.

Or just buy a running K75 and ride it.

I suppose I should admit that my motavation on this project is not to build a bike around it. Sorry if that upsets anyone but at least I'm being honest about it.

Marvin M wrote:I suppose I should admit that my motavation on this project is not to build a bike around it. Sorry if that upsets anyone but at least I'm being honest about it.

????

Kart, paraglider, hovercraft???? The brick engine has been used in many non K application. 

Certainly no need for an apology - most of us are intrigued by all projects that have even the vaguest thing to do with a K. As per my earlier post - you are doing it the right way, taking a discarded piece of a K and making something of it rather than taking a half decent K and breaking her into a frankensomething.

Great link Duck, sorry but thought I'd add a quick edit to  stress that my frankensomething comment above is not at all associated with your project which was flipping amazing!

Marvin M wrote:I suppose I should admit that my motavation on this project is not to build a bike around it. Sorry if that upsets anyone but at least I'm being honest about it.

A member over here has a hoverKraft powered by K!

https://www.k100-forum.com/t4352-fpr-and-injectors-alternatives

I had a guy in CA who bought a K75 motor to use as the power plant for a go-cart.

Another guy needed some parts to bench run a K75 that he planned to use in an ultralight.  This kind of shocked me because light and K bike usually aren't used in the same paragraph.  After a few months I guess he did some math and realized the K75 motor was not a good powerplant for an ultralight.

A few years back I recall reading that the BMW R1200C (as well as other Oilheads) was considered a good motor for ultralights due to its high torque at lower revs, fuel injection, relative lightweight and air/oil cooling.

Well I'm not considering using it for an ultralight.... Yet ! Lol
So far I've only investigated a wiring diagram and while watching TV I've been stripping down the loom. Hoping to familiarise and simplify things somewhat. TBH I've worked on cars with less wiring than this.