fuel injection for the xs/xj series

[tony7914]

hey there!!
i thought i would toss this idea out to some of you folks and see if a few people could get together and make it work....i have seen aftermarket fuel injection systems sold for cars and i was wondering if it would be possible to make or buy something like this for an xs\xj? some thought would be what type and size injectors, how to mount them, how to control them, and cost.......many of you folks have the education and skill to make something like this work, and i would be the first to buy one from you (or test prototypes) i've had some thoughts on the idea but get stumped on the controler part.....again it's an idea that might be worth looking into..........

[Jerry]

This has been discussed a few times. A couple people got together to try and come up with a lower-cost alternative to the $1,000.00 systems out there, but as yet nothing has come of various individual efforts.

Kawasaki had fuel injection on their in-line 4s during the early '80s. I picked up a service manual on their system, but it doesn't offer much information on theory and design. However, it does look like the system could be adapted to the XS/XJ with enough time and energy. I had hopes of buying a system - they do show up on e-Bay once in a while- but I lost my garage when I moved and have not followed up since then. (2001)

Like a 6-speed transmission, there is a lot of interest in a workable fuel-injection system. If you come up with some ideas, let us know!

[TheDjost]

I have an idea that I've been brewing

I hate carbs, so I'v been thinking about converting to injection.

I was thinking of using the whole throttle body out of a chevrolet metro 4cyl. It would fit quite easy with just a bit of grinding(on the chevy manifold, to make it fit in the stock ruber boots).
The spacing is the same as my 750. Not sure about the 1100. The computer would probably be adaptable also.

If you want to tackle this, make sure you include in the plans a redo of the muffler setup (unless tou have a 4-1) because you have to have a point to put the o2 sensor, and that needs to be in the path of all the exhaust gasses.

In fact, I just got my hands on a scrap chevy sprint(the piston rings are dead, but the injection is OK) and I will be looking into the project.

The reason I came upon this idea is the fact that the suzuki swift gti crowd sometimes use bike carbs to increase total butterfly size. (Bear in mind that that they are running 1.6l twin cam engines, with mods, so...) I don't think that the smaller butterfly will impede that much on the bike performance, since the butterfly is larger than the butterfly that is on each carb, and the pistons only suck in air one at a time.

I think that I can take care of the intake part and the computer part of the system, but I can't weld so I'll be in trouble to make a proper exhaust system to mount the sensor.

-Justin

[Jeff]

How far back can the O2 sensor be? Even on a 4-2, there is a crossover tube where left and right mix.

[TheDjost]

Mind you I'm no expert in exhaust design, but I would think that we would need to have a 4-1-2 made.

The closer to the engine we can put the sensor, the better. It likes HOT gasses.

The question I've been wanting an answer for is this one:
What if you don't sample all gases? If I were to put a sensor on only one side and sample 2 cyls, would it be enough, taking into accuount central injection, where all cyls get the fuel from the same source. If 2 cyls are running right, they all should be.

Then any 4-2 exhaust might do the trick. I'm not sure about the crossover... Like I said, the sensor needs hot gasses, and lots of flow. I'd guess that the crossover doesn't get all that much gasses going through it at all, maybe 10-15%?

I was thinking of simply welding a bunch of y joints together to make a 4 to 2 to 1 to 2 adapter.(I have an XJ, and tose don't look that good with a single muffler in my opinion.)

But those that have a 4-1, all that you need is to drill a hole in the pipe under the bike, and have a cocket welded for a universal o2 sensor.


Another thing I've been looking at is mechanical injection, like the one off an older passat.(you know, the one with a plate that lifts in tha airflow and opens a mechanical valve to feed the injectors)
The thing is that the passat had 4 injectors, so you could gut out the carbs except the slides, and butterflies, and fit the injectors in the needle valve seat in the carbs, so they point up. But there would be little point in such a system, since it's mechanical and has to be adjusted like a carb. Only advantage is that there is a lot less of things to adjust. But no computer and no O2 sensor needed.

-Justin

[Hobbit]

Technically you don't need an O2 sensor. The sensors main purpose it make the exhaust mixture oscillate from lean to rich so that the oxidation and the reduction beds in a three way catalytic converter can function. (Called closed loopoperation.)
The mixture can be set based off of engine temperature like when a car is first started (called open loop operation).
Most early FI systems (electronic or mechanical) operate in the open loop mode.

[Jerry]

For a 5 minute basic explanation of the most common 5 types of fuel injection systems, see:

http://www1.union.edu/~grantm/general_information.html


If you click on the Multi-Point link it will bring up a diagram of a typical FI system

The early kawasaki system I mentioned used an air-flow sensor in the airbox as the main input. and included a fuel pump. This is typical of a CIS-E (Continious Injection System) design.

There are 1 or 2 kawa systems on ebay right now, search on Kawasaki Fuel Injection. Going price sems to be around $100.00.

Its not the mechanicals that are the problem, but getting the sensors and computer that meters the fuel delivery.