3 cylinder electronic ignition conversion 2

[johnnyuk]

Hey folks,
Noobie here!

Im looking for some auto electrical advice....
I need to convert a 3 cylinder 2 stroke engine with PVL electronic ignition to a UK spec electronic ignition where the advance and retard can be easily adjusted.
Any ideas would be most appreciated.
I have attached a file showing a picture of the wiring diagram.
Many thanks in advance.

Johnny

 

[bradrs]

What is a "UK spec" electronic ignition? In a previous life, I designed many ignitions that were sold in the UK for motorcycles, but was never told about a UK spec. Maybe that has changed?

PVL does have some digital versions of their ignitions that are programmable. One of these may do the trick. If not, there were some other european companies developing programmable ignitions for 2 strokes. I believe some of this interest was based around making replacement ignitions for the old Kawasaki H2 engines from the 1970s.

And there was also a UK based company that made aftermarket replacement ignitions for newer 3 cylinder Triumph motorcycles. I believe that was 4 stroke, but if they fire wasted spark, it could still work well enough.

Is your 3 cylinder firing with an even pattern(with a 120 degree crankshaft), or is it firing like it is a 4 cylinder, missing 1 cylinder(180 degree crankshaft)?

 

[johnnyuk]

Hi
Many thanks for your info.
It is firing at an even pattern of 120 degrees.
The reason for the conversion is for something more reliable.
The application is a Polaris 1200cc jet ski.
The polaris set up is a nightmare, firstly as its american, and secondly the parts are now becoming harder to get.
My idea was to convert it to a more up to date system so timing could be easily adjusted for optimum performance.
Im a little out of my depth when it comes to electronics so you will have to excuse my ignorace.

 

[waross]

The polaris set up is a nightmare, firstly as its american,

Not particularly PC on a site that is predominantly American. Anyone who remembers Lucas, Prince of Darkness will not be as prejudiced towards American ignition products.
Grin

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[NickJ67]

Have to agree that we from the home of the Prince of Darkness shouldn't really throw stones.....!

Couple of thoughts. Neither is especially elegant for your application, but it's a starting point.

http://www.autosportlabs.net/MegaJolt_Lite_Jr.

Megajolt light is a programmable ignition controller used in conjuction with the Ford EDIS system hardware. The EDIS system was designed with double ended coil packs as a wasted spark system for 4 stroke engines but I see no reason why you couldn't use it to fire single ended coils on a two stroke. You would need to use the EDIS-6 version on s 3-cyl 2 stroke. The clunky parts are that you'll need a crank position sensor in the form of a 36-1 toothed wheel and magnetic pick-up (no idea if this is practical on your engine or not) and also that you need to mount the EDIS box and MJL ECU. The good news is that the timing will them be fully 3D configurable from a laptop.

Similarly, you could use a Megasquirt ECU in ignition-only form (unless you want injection as well). This can be used with the EDIS hardware but also, with a few fairly simple mods, it can trigger coil-packs direct. This will also need some kind of crank position sensor but it is a bit less fussy about the methods.

A bit of googling suggests this might be helpful also

http://www.boyerbransden.com/micromarkiii.html

Cheers

Nick

 

[dgallup]

There are a lot of 2 stroke 3 cylinder engines, outboards, motorcycles, other PWC. Wouldn't it be easier to fit one of those?

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[bradrs]

Fortunately most of the inferior US designed ignitions I made seemed to still work on the superior UK spec electronics. But will forever remain a mystery to me why someone would remove good UK spec electronics to replace it with my rubbish

Looking at the wiring, it LOOKS like you have 3 sensors mounted on the flywheel, each one that corresponds to firing one of the 3 coils. Is that correct? If so, you could replace your CDI with 3 programmable dirtbike CDIs, and not have to change/add any mechanical hardware. There will be a little challenge in getting all 3 to power off the single winding that was used for charging the CDI on the stock system. So it might be easier to use a 12V DC type dirtbike CDI, there are several bikes/quads that used those. Look for an electric start bike/quad programmable ignition. The downside of this is that you have 3 separate ignitions. Cost is higher, and you need to individually zero out and adjust/program them.

There are several ignitions available for Yamaha watercraft. Programmable, multicylinder, etc. Cost is a little high, but not too bad. The main issue, would be adapting them to work with your setup. There are a lot of unknowns when you try to adapt one aftermarket CDI to work on another setup.

4 stroke stuff might be able to be modified to make it work, you just want to really be sure you know what programmability range it has. Some may only allow a small range of adjustment, and you need a good bit more to get the most out of the 2 stroke.

The MegaJolt would be a good option, although it might be a bit challenging for someone not familiar with electronics. It will require more fabrication work for sure. But I'd guess it'd be easier to get help with the electronic side of things on the forums dedicated to the MegaJolt.