700x efi conversion

So im going to be doing a complete rebuild on s 700x and i was wandering if converting to efi could be done ive seen people do it with the air cooled motors but never the x models if someone could point me in the right direction i would appreciate it

 

You have come to the right place as we have a member who has done the conversion to EFI, and it looks like it is defenitaly one of his skill sets.

@SQLGuy

 

You can't just buy a bike kit - but there are car kits that might do it. It needs to be compact, and most car kits have added so many features over the years they've got big. SQL guy is an electronics expert - are you?

 

Ive seen the air cooled modlles using gsxr throttle bodies and a micro squirt ecu would that also work got the water cooled x model ill be doing a complete engine rebuild to go along with major changes to the entire bike

 

Have any in mind ?

 

I do not think that it would matter if bike is water or air cooled start a conversation with SQLGuy and ask him about efi he should be able to point you in the correct direction.

 

No, not fully up to date with the latest stuff. Water cooled is better - temperature, or coolant temp compensation is an essential correction - @SQLGuy would have embedded a sensor in the head somewhere I guess?

 

https://xjbikes.com/forums/threads/xj750d-fuel-injected-does-anyone-out-there-have-one.103977/


https://xjbikes.com/forums/threads/yet-another-efi-conversion-on-1980-xj650.47607/


https://xjbikes.com/forums/threads/fj600-fuel-injection.124078/

 

parts and stuff

https://www.motorcycleid.com/yamaha-xj750-maxim-fuel-management-systems/

 

Even when fuel injected and turboed that XJ idle is unmistakeable.

 

Water cooled is a bit easier, since there's a lot more choice of temperature sensors for coolant. I used a Porsche 914 block temp sensor for my setup.

I'm not actually sure what your best choice is for a current ECU. I used a Microsquirt v1 - one of the very first ones to be made. Microsquirt is a weather-sealed case with an ECU that can do two channels of ignition and two channels of injection. It has a lot of options for different sensor inputs, and can run with a wide variety of engine setups.

However, when they came to v2 of Microsquirt, they removed the ignition drivers. I'm not sure exactly why. So, in my setup, I have the Microsquirt mounted where the TCI used to be, and it runs fuel injection and ignition with coils from a Saturn (SC, I think), but, in a Microsquirt v2 install, you would need either external ignition drivers, or coils with built-in ignition drivers. It is possible to do sequential ignition with Microsquirt by repurposing a couple of the LED outputs to drive coils, so, running four logic-level coils would be an option. MS3 allows for fully sequential without customization, but it's a bigger ECU. The Microsquirt module is easier to modify for fully sequential, but I'm not sure what it has for a case or how the connector arrangement will work for an installation like mine... you may be able to build a more customizeable Microsquirt using a module and a Microsquirt case and connector.

Typically, what people do for MC conversions, is to get throttle body / injector sets used from eBay, from a Hayabusa or some other four cylinder transverse FI bike. Car kits are not a good idea, as the injectors will be often be too big, the ECU will usually be too big, and they won't do anything about induction.

My whole setup looks like this:

Microsquirt 1.0 modified internally to add Bluetooth and two additional injector channels (also uses a replacement NCV1124 VR conditioner)
36-1 crank wheel using one of the stock VR sensors (pickups) for crank position and primary timing
Extra "tooth" welded to intake cam end and a BMW cam position sensor for additional timing of intake/exhaust stroke
Saab/Bosch fuel pump installed in the tank; petcock replaced with fuel return tap; fuel supply tap added to other side of the tank
Additional relays for ECU power and fuel pump
Custom intake manifold
Ford Escort throttle body with attached idle air valve - welded tab on the frame to allow a custom length throttle cable to connect to it
Custom fuel rail, with Hyundai 40PSI fuel pressure regulator
Ford injectors (not sure the original application) - Bosch style with four holes and rated at about 14lb/hr
One MAP sensor for manifold pressure, and a second one for ambient baro
GM inlet air temp sensor in the air box - air box cut down and modified with a cover plate and an flexible air hose into the throttle body
Porsche 914 block temp sensor screwed into the back of the block
LC-1 wideband O2 sensor
Golan Products fuel filter
Saturn two-tower Hitachi coils with driver wires soldered to their drive tabs, and custom 7mm spark plug wires and NipponDenso caps

This allows me to run fully sequential fuel injection with wasted spark ignition and speed density fueling. Warm up is controlled based on block temp. Idle is controlled via PWM of the Ford IAV. This allows a slightly higher idle when the engine is really cold, and good return to idle under all conditions. The second MAP sensor allows adjusting fueling as elevation changes during a ride. The wideband allows auto tuning of the VE table and some amount of quick correction where the VE table isn't correct for conditions - a newer wideband, like an LC-2, would be better for this.

In addition, I converted most everything to LEDs, to have more current available to run the fuel pump, ECU, IAV, EGO, and injectors.

Previously I had been running batch injection, and then semi-sequential. I found that fully sequential made the idle smoother and the engine more responsive to tuning changes.\

I had problems keeping crank position synch above 5000 RPM. B&G (the Mega and Microsquirt people) had issues with their initial Microsquirt VR circuit. I think these are largely fixed in later versions, but switching to an NCV1124 fixed mine well.

A welder, an angle grinder, a mini-lathe, a drill press, a timing light, and some thread tapping tools are all pretty helpful here, as are a meter, maybe an oscilloscope, soldering equipment and skills.

 

S

So the micro squirt ecu dose not run 4 ignition plugs?

 

It can, if you repurpose the LED outputs, and use coils with their own drives/igniters.

But, with wasted spark, you only need two ignition coils.

 

@SQLGuy - have you not thought about going individual throttle bodies?

 

Thought about it a bit, yeah, but didn't like the lack of closed loop idle control or some other trade-offs I would have to make. I'm quite happy with the result I have now, so, no need to replace it.

 

@SQLGuy so ive never converted anything to efi just dealt with things that already have it so whats waisted spark?

 

You already have wasted spark. That's how ignition works without a distributor or cam sensor. The 1 and 4 spark plugs fire in series from the secondary of one coil, and the 2 and 3 from the secondary of the other coil. Timing is based on crank position, so each cylinder gets spark near the top of compression and near the top of exhaust. Each coil fires once per crank rev.

 

So if i connected the ecu to the existing coils it would work ?

 

Yes, you could drive the existing coils with Microsquirt. I went with the Saturn coils because I wanted something with a bit more energy, and, since I can set the dwell as needed, I had more flexibility on replacements than I would with the TCI.