How to trigger MS on my GSX 1100

jkbh · Post by **jkbh** » Mon Apr 04, 2005 12:49 am

Can anyone help me with this?
I have just installed MS on my turbo charget motorcycle.(Gsx1100-82).
The only thing I´m not sure about is the trigger.
The engine is a 4 cylinder engine with 2 ignition coils.
A was planning to use Alternative injection with 2 squirts per engine cycle.
And normaly if the engine have just one ignition coil you get 4 ignition signals per engine cycle.
But in this case if I just take the trigger from one coil i just get 2 ignition pulses per engine cycle.
Can I do like this and just tell MS that it is a 2 cylinder engine or do I have to take the trigger signal from both coils.

Stickboy9137 · Post by **Stickboy9137** » Mon Apr 04, 2005 1:04 am

Jim,

The way I was going to trigger my MS from my motorcycle (CB900C) is to use a diode on each - lead from the coil packs going to a single zener diode. The idea and part numbers is listed on the Megajolt website. The diodes are 1N4004 and the Zener is 15-18V. It doesnt list a part number. That way you can tell the MS to be a 4 cylinder. The other method is to take the output off of only 1 coil and tell the MS it is a 2 cylinder.

Jody

(posted by email)

jkbh · Post by **jkbh** » Mon Apr 04, 2005 2:56 am

Thanks!
I did that on another motorcycle with different control system.
I think this is better than use only one coil.
But why the zener diode?
And what´s the link to the megajolt site?
/JKB

Stickboy9137 · Post by **Stickboy9137** » Mon Apr 04, 2005 2:59 am

The Zener is to keep the trigger level from overloading the Optoisolator.

Jody

(posted by email)

jkbh · Post by **jkbh** » Mon Apr 04, 2005 12:38 pm

Thanks Jody!
Are going to try it this week.
I will post pics and info when I get the engine up and running!

/JKBH

Its nice to se so many helpful MS users on this forum!

Stickboy9137 · Post by **Stickboy9137** » Mon Apr 04, 2005 2:34 pm

If you get a good part number for the Zener please forward it to me so I can buy one. I know it will work, I just havent set mine up to do it yet.

Jody

(posted by email)

jkbh · Post by **jkbh** » Tue Apr 05, 2005 1:10 pm

How about a BZX85-C16.
You can find it at Farnell. Farnell Art.Nr: 369-860

Are you sure this with the zener will work?
I read on the Megajolt site that this 3 diodes was to get high spikes to get a tacho running.
But in this case we don't want to get high voltage spikes.
Wouldn't it be better to connect the zener to ground instead.So when you get to high voltage the zener shortcut to ground an regulate the ignition trigger to the MS.
Correct me if I'm wrong!

/JKBH

Stickboy9137 · Post by **Stickboy9137** » Tue Apr 05, 2005 1:16 pm

The zener hooked in series will act like a constantly variable resistor. If the current goes up the zener will drop more voltage, keeping the level relatively the same. You could do a zener to ground but it will not work fast enough. Usually zeners in that configuration are for slow moving power supply voltages and not constant spikes.

Jody

(posted by email)

ArttuH · Post by **ArttuH** » Wed Apr 06, 2005 7:56 am

I connected the trigger signal to one coil on my GSX. Then I told to MS that the engine is 2 cylinder. Works fine.

One tip which may be helpful for you: I had problems with rpm spikes at 2000-3000 rpm. I solved the problem by replacing the capacitor in the input of the optoisolator (C12 on MS 2.2 board) with larger one. 1-2uF seems to be suitable value.

BTW, please remember to inform us how your project is going. I'm very interested to see results because I have also planned to turbo my GSX

jkbh · Post by **jkbh** » Wed Apr 06, 2005 8:52 am

I will post info and pics soon.Promise!
I started the engine today.I shouldn't have because I had no oil in and no fuel.But I just couldn't wait so I just tried to start and it did.Can ju belive that.
And I havent even set up anything in the MS.
I'm going to mount the engine temp sensor on the cylinder head tomorrow and fix a idle speed adjustment on the throttle body.
Then I am done.Just tuning left( I hope

.
Maybe I will post some pics tomorrow.

/JKBH

jkbh · Post by **jkbh** » Wed Apr 06, 2005 9:00 am

When I thought about it I now realise that you are right about the zener Jody.
To get a 15 volt zener to work you must have a specified current through the diode.Otherwise it won't drop any.

Jkbh

TT350chevelle · Post by **TT350chevelle** » Wed Apr 06, 2005 9:10 am

jkbh wrote: I started the engine today.I shouldn't have because I had no oil in and no fuel./JKBH

That is one very special bike..

Fuel and Oil Optional...

Brad J.

jkbh · Post by **jkbh** » Sat Apr 09, 2005 11:33 am

Arttu, I would like to know more about your GSX1100.
I'm just starting to tune my MS.
Maybe your info could spare me some problems.

/Jimmy

shapcott · Post by **shapcott** » Thu Jun 04, 2009 5:34 am

Sorry to resurrect such an old thread but my query sort of follows on from this story..

I have fitted megasquirt to my 4-cylinder motorcycle fitted with two coils. Based on the advice in this thread I have taken the trigger from one coil and setup the MS as a 2 cylinder bike. I am running fuel only.

My friend has an identical bike running both fuel and spark, he has an identical injection system and has a well developed set of constants and VE table which I would like to straightly use. In his setup he has 'number of cylinders' set to 4 (of course) and his 'required fuel' settings are 8 top and 4 in the bottom box. When I set my MS as a 2 cylinder bike it changes the 'required fuel' settings to 8 top and 2 bottom. I know this has a direct effect on the VE tables so I would like to get this setting right so I can use the same VE table.

Is it a case of simply increasing the top box to 16 to get the bottom box to read 4 to end up at the same end result of my friend, or have I misunderstood it? I have read the req_fuel chapter many times but my tiny brain can't grasp it all at once

Thanks for any advice in advance..

Steve

shapcott · Post by **shapcott** » Thu Jun 18, 2009 10:21 am

Bump..

Nobody can help me? I'm ready to start the bike in the morning but I still don't know what to do about this required fuel setting

Thanks, Steve.

Matt Cramer · Post by **Matt Cramer** » Thu Jun 18, 2009 11:08 am

What's his number of squirts set to?

shapcott · Post by **shapcott** » Fri Jun 19, 2009 8:58 am

Hi Matt,

Thanks for the reply

Here are the constants, my friends on the left and mine on the right.

Matt Cramer · Post by **Matt Cramer** » Fri Jun 19, 2009 9:02 am

That does look a bit weird, but it ought to run like that.

shapcott · Post by **shapcott** » Fri Jun 19, 2009 9:06 am

Thank you.

So only the required fuel in the lower box is used in the equation and providing it is the same as my friends, then the VE tables should be the same scale..

Matt Cramer · Post by **Matt Cramer** » Mon Jun 22, 2009 11:59 am

I'm pretty sure it will be the same, though I am a bit puzzled this even happened...

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