Hello. I would like to hear your thought on this one!

I am doing a project with my -91 K75 where I replace the old Bosch L-Jetronic ECU from my bike. The end-result will be modern closed-loop engine control for the fuel injection.

Much like discussed here:
http://www.motobrick.com/index.php?topic=936.75
https://www.motobrick.com/index.php?topic=9303.0

As I have been planning the project, I can see that the swap could be done almost plug'n'play with using the original wiring loom and original connectors. Biggest changes would be installing a wide-band lambda sensor and maybe getting rid of the MAF sensor since it reduces power by reducing airflow.

Do you think there could be others interested in upgrading their fuel system? The benefits should include: 
- better fuel economy 
- more torque/power
- much better throttle response
- no hassle with adjusting the old system with exhaust CO analyzer (how many even does this properly?)
- no longer dependent on 30yo tech and used parts...

and all this up to you to control with stand alone ECU, if you want to dive into it. (there should be some base maps to use)
The unit could also control the blinkers and support some retrofitted dash. (my blinker unit is done )
What do you think?


I am aiming to run my machine on E85 but for most I guess the refit could cost around 600€ (in EU with VAT) in a package that would include all wiring, connectors and sensors. The price on these components have become quite attractive in recent years. Possibility to also control the ignition should be considered as here it is left to the original ignition controller.

Edit: My point is to get an idea if its worth trying to put together this type pnp kit. The whole thing would be much easier as one-off, without full pnp readiness but I might look into it if it has some demand as such.

About the results you can reasonably expect,  the only eventual gain would be about fuel economy, maybe emissions, but nothing that a fine tuning of the OEM equipment could give you. 
But no gains of power or torque. At all. A modern fuel injection does not gives by magic an engine extra power: it allows to avoid losing power only once you made mecanichal mods that do effectively improve power: rebore cylinder, longer opening cams, high compression pistons, bigger valves, low friction materials, etc.
The MAF does not reduce power nor airflow. The K75 has the exact same capacity/power ratio than the K1, running with Motronic so without MAF: 100HP/L.
The MAF could, theoretically, be restrictive, but only  at full charge, full rev...if the design of the intake pipes and the cylinder head were not much more restrictive than the MAF. In other words: when a meatball is stuck in your trachea, spitting out your denture won't improve your breatingh.
The basics of the architecture of a K75 are preventing this engine to deliver more power at high revs: it's a long stroke 2v engine, excellent for low rev torque and smoothness, but unsuitable for revving. You can worry about the MAF restrictive effect above 12000 rpm. Reach them first.
The Jetronic injection also appears to be a simple but extremely reliable system 40 years later, with components available anywhere on the planet for very cheap money, and that you can diagnose with a simple volt/ohm meter. Any modern injection system requires a PC and dedicated software... That's why I chose this model to travel: all the tools and spare parts that could fail fit in the seat boot.

Furthermore, if you want to run E85, so you will first have to deal with the absolute incompatibility of all the components of the fuel injection with it; fuel pump rubber, fuel hoses, gaskets. See your avatar pic! You will also have to increase the fuel flow by 25% and pressure to compensate the poor energy of E85, so to change the fuel pressure regulator, the injectors, potentially the fuel pump and, of course, create a specific map, with a power bench to validate it.

I've been talking with some people who had prepared K75 and K100 engines for race: You could reach +5% extra power with a real state of the art preparation (not stacking up so-called perf parts), but it will be a 5 number bill. 10000$ to go from 75 to 79 HP.

So try implementing your new system, I'm curious about this project!
But don't expect much about it. Making it run as well as a Jetronic will already be a success.

Well said jbt. I fully agree. Keep it simple and standard.

I agree with all that JBT wrote.  As it is, the K75 engine is amazingly reliable, smooth, powerful and pleasant to live with with the stock Jetronic engine system.

However, a Megasquirt retrofit would give some mental entertainment during the long Finnish winter.

Point-Seven-five wrote:I agree with all that JBT wrote.

However, a Megasquirt retrofit would give some mental entertainment during the long Finnish winter.

I agree with JBT, too. Once I find something good, I try to preserve it, not alter it. Partially, that's because I'm not industrious but also it's because I'm appreciative.

Here's the summary of the Megasquirt outcome, The experimenter and writer is probably now involved in his career as a physician and I hope is still enjoying his elderly Moto Guzzi California.

I like to travel a bit too and the comment about spare parts fitting in under the seat is so correct. Any others are also very easily available and its really hard to beat that.

I did put E85 in my K one time in France.....the comment about increasing fuel pressure and higher flow...... swap the fuel pressure regulator to K1100.......also swap the injectors to K1100 and voila. I am going to try that some time. I moved the FPR on my K100 Sprint because the fairing doesn't have a removable panel to get at it. Now its accessible, along with the injectors, without removing any plastics.....