3 cylinder 2 stroke, spark and ignition

[axelg89]

Hi,

I'm building a 3 cylinder 2-stroke with 120 degrees between the cylinders and would like to know my options when it comes to MS. I would like to control both ignition and fuel and do so at a relatively low cost. The system is going on a bike so I have a limited amount of space and power to support the system.

What would you recommend? I've searched a lot but come up with very little regarding 3 cylinders. If I understand correctly I can either run MS1/2 with EDIS 6 or MS3X with full sequential timing options. Is there something else? MS3X seems like quite an expensive way and over complicated way to control my little 2-stroke engine...

Would greatly appritiate any input.
Best Regards
Axel, Sweden

[dontz125]

Hi, Axel.

The MS2 running Extra code can control up to 6 spark channels and (with a mod to the MS2 daughter card) up to 4 injector channels. 3+3 sequential on a 2-stroke is no issue.

[axelg89]

How about microsquirt, how would I go about controlling ignition on a 3 cylinder?

Thanks for the answer

[Matt Cramer]

It can run three spark output channels with the current code, but you'd have to fire all the injectors at the same time.

[dontz125]

I have a test board in hand to add the 3rd and 4th fuel channels of a MicroSquirt Module to a V3.0 MicroSquirt. This will be fully internal and transparent to the end user, with re-purposed AMP35 pins for CH3, CH4, and PA0. B&G were kind enough to donate a dead V3 for dry fitting, and it fits perfectly.

Now I just have to practice installing it on the dead one (delicate soldering of wires to the processor itself), then perform the surgery on a live test box ...

[axelg89]

I have a test board in hand to add the 3rd and 4th fuel channels of a MicroSquirt Module to a V3.0 MicroSquirt. This will be fully internal and transparent to the end user, with re-purposed AMP35 pins for CH3, CH4, and PA0. B&G were kind enough to donate a dead V3 for dry fitting, and it fits perfectly.

Now I just have to practice installing it on the dead one (delicate soldering of wires to the processor itself), then perform the surgery on a live test box ...

Hi, that sounds very interesting I must say... But I guess it will be a good while before that's something commercially available?

Could I control an EDIS module with the microsquirt and run wasted spark and that way control both fuel and spark with microsquirt? Or would that draw to much power for my stator to handle?

Best Regards

[grom_e30]

The cased microsquirt can run up to 4 ignition outputs, ign1, ing2 and using a pull up resistor connected to the Wled would give you the 3rd spark output. as already said as there is only 2 injector drivers all 3 would need to be connected to channel1 and fired at the same time.

[axelg89]

Does anyone here run their engine that way? All injectors firing at the same time? How big of a disadvantage will it be? I read on the net that many of the early 1990s cars were wired this way but I can't find anything more concrete on performance disadvantages using the system...

[grom_e30]

how exactly do multi cylinder 2 strokes work??? is the inlet charge (fuel & air) for all cylinders mixed together in the crank case and then distributed or is it 3 totally independent chambers?

[dontz125]

Three independent cylinders, with seals on the crank between cyls. Otherwise the crankcase volume would be effectively unchanging, and no mix would be drawn into or pumped out of the cases.

[billr]

" 3 cylinder 2-stroke with 120 degrees between the cylinders"

I'm more curious about that... are these cylinders arranged like a radial aircraft engine?

[racingmini_mtl]

I think he meant the crankshaft.

Jean

[axelg89]

" 3 cylinder 2-stroke with 120 degrees between the cylinders"

I'm more curious about that... are these cylinders arranged like a radial aircraft engine?

As Jean sais the cranking separation between the cylinders is 120degrees which is pretty obvious as 360/3=120 i guess. The cylinders are however parallel as seen below in the picture.

As dontz sais the crankcase is separated for the different cylinders using seals which can also be seen in the picture...

[grom_e30]

With them being 3 different chambers i would assume 3 throttle bodies and inlets so you wouldn't have a fuel scavenging problem going on but i do wonder how important the injection timing would be on a 2 stroke having less time to atomise the fuel and mix the inlet charge