MS-II on Honda GX-35 Engine

[gshoger]

Hello,

I am a mechanical engineering student at the university of Illinois. I have been handed down a project and am trying to figure out how to use the MS-II on a Honda GX-35 engine. It is a single cylinder 4-stroke engine with a pull start. I have made a custom intake that can support some sensors including the MAP and temperature. I can communicate with the MS-II from my laptop and run a test which starts to squirt the fuel. I want to get the engine running with the EFI but don't really know where to start. I have read a lot of the user manuals and still cannot figure out what to do. I was wondering if someone could help me out and tell me where to begin.

Some specific questions:
Can I use megatune to control the throttle?
Can I use MS-II with a pull start engine?
When I have the gauges up on the screen (RPM, MAP, throttle) the RPM is red. The engine has a magneto on it and it is connected to the MS-II. Does this mean that there is something wrong with the magneto? or the way it is connected to the MS-II?

Thanks for any help,
G

[Matt Cramer]

The MS does not have electronic throttle control.

In a fuel only installation, you could probably get things working with a pull start. Spark control will be a challenge.

How exactly do you have the MS tach input wired up?

[gshoger]

Someone else actually wired up all of the sensors before me. But from what I can tell, the magneto in the engine is wired into a sensor on the ECU. I'm not sure if that will work. When I communicate with the engine, all the gauges that come up on my laptop are white except for the engine speed, which is still red. Would the engine actually have to be running for the magneto to work?

thanks,
G

[Matt Cramer]

I need to know exactly how you have the RPM input configured inside the MS2 and what exactly it is connected to on the magneto.

[texasZX]

Some specific questions:
Can I use megatune to control the throttle?
Can I use MS-II with a pull start engine?
When I have the gauges up on the screen (RPM, MAP, throttle) the RPM is red. The engine has a magneto on it and it is connected to the MS-II. Does this mean that there is something wrong with the magneto? or the way it is connected to the MS-II?
G

1) No, AFAIK there is no cruise control or active throttle type system (yet).
2) Yes, whether the engine as a pull or electric starter is irrelevant. I've pushed started EFI cars, same thing.
3) Mags are "fixed" timing and I'm not sure how you connect it to MS since the "coil" on a magneto has no connection to a battery (no "-" terminal to pick up an RPM signal from). You could probably adapt some sort of wheel and VR pickup to get a tach signal to the MS.
4) Magnetos don't work till the engine spins. The only wire (beside the high tension wire) I've ever seen hanging off a Magneto is a ground wire (as in the only way to kill the ignition in a magneto engine is to ground out the magneto). You'll need to device some sort of tach signal.

[Mike_Robert]

4) Magnetos don't work till the engine spins. The only wire (beside the high tension wire) I've ever seen hanging off a Magneto is a ground wire (as in the only way to kill the ignition in a magneto engine is to ground out the magneto). You'll need to device some sort of tach signal.

I don't know about the Honda magneto, but the wire you use to ground/kill the magneto on a Briggs/Tecumseh definitely has a signal in older engines. As a teenager trying to mod a minibike I shockingly discovered that there's signal you can most definitely "feel". IIRC, it felt very much like primary flyback voltage from a Kettering. I'll throw a scope on that lead on my much newer lawnmower next time it's called into active duty, this weekend I suppose.

[texasZX]

I don't know about the Honda magneto, but the wire you use to ground/kill the magneto on a Briggs/Tecumseh definitely has a signal in older engines.

Well, I was thinking that signal pickup might be the problem.
A standard ignition system coil needs a ground to work.
A magneto ignition system coil uses a ground to stop working.

Hooking up a tack line to a standard ignition system coil negative terminal is not a detriment to the ignition system because a path to ground is required. If you provide a path to ground on a magneto then it shunts the whole works. Maybe he could do some kind of "induction" pickup on the spark side (like a timing light does) and get a signal?