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Old 07-29-2012, 09:23 AM   #16
hrcs90
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Cool, keep us posted on your findings.
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Old 07-29-2012, 10:14 AM   #17
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will do. It's going to be slow progress for a while, but i will update my tread with new info when i have it.
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Old 07-29-2012, 01:04 PM   #18
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Quote:
Originally Posted by Reino View Post
I am well aware of the differences regarding 2t and 4t. As i have explained in my first post, I am scrapping my cdi with a programmable unit.

I am not going to stop at the ignition side. Also having access to a dyno is not a problem for me.

This is going to be a long term project (3 or 4 years).
If you are serious then I would suggest you look for an ignition system with sensor inputs for both heat and pressure, and remember that about 95% of manufacturer claims about programmable CDI units are BS.

For full 3D map you will need a 12v DC control unit, and in most cases some sort of toothed wheel ignition trigger wheel, so the control unit knows the exact engine position at any given time.

In regard to 2T applications its worth remembering that any system without pressure/heat sensor inputs, will mean that a map which makes very good power on one day, may well burn a piston the next.

This is the main reason OE 2T ignitions have pretty conservative settings, and why someone who doesnt know what they are doing can very easily destroy motors with systems that can actually be mapped.
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Old 07-29-2012, 01:56 PM   #19
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Thanks for the info Twin-shocker.

The sensors i am going to use for the ignition side is as follows: intake air temp, engine temp, map, throttle position sensor and my project calls for a toothed wheel( 36-1 ).

This hole system is going to run off a battery or a capacitor-battery substitute. My bike already has the 2k-3 stator (110Watt's of power). I am also going to make the system in such a way that i can go to original setup if need be.

Reino screwed with this post 07-29-2012 at 02:07 PM
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Old 07-29-2012, 02:12 PM   #20
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That sounds fine and should work well, after you establish what works on the dyno, and make careful notes regarding conditions when you are making the runs.

When you are doing the dyno runs, use a thermocouple under the spark plug washer, as well as EGT, and load as many maps as you can into memory, and use them in accord with atmo conditions on the day.

If its a road or drag race bike use a li-po battery to power the system, if its an off roader you should be able to run off rectified ac generator, using a capacitor to help with starting.
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Old 07-29-2012, 02:17 PM   #21
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I am considering the use of a knock sensor as a fail safe, the control unit can utilize all the the mentioned sensors in this thread and then some.
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Old 07-29-2012, 02:24 PM   #22
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The only sucky thing about going into detail with 3d ignition is that I would have to redo every thing if I use a different pipe. Even if i use the same type of pipe there are still small production variances between the same series pipe.

I will probably make a map on the edge and dial it back slightly to make it more tolerable of production variances and normal wear(dings).
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Old 07-29-2012, 10:00 PM   #23
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Atmo conditions change from day to day, and if you want max power from a 2T race motor, you will need to try various different maps to take this into account. I would imagine its going to take 2-3 days on a dyno (with an experienced operator) to come up with baseline maps, and costs are going to be relatively high, especially so if motor damage occurs.
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Old 07-30-2012, 01:44 AM   #24
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the ignition map resolution is 12*12 (i can change it to focus more on rpm than on load or viceversa).

I am going to run 20 degrees advance at 100% load and 30 degrees at 0% load. The dyno i am going to use has to be able to hold the engine at a certain load and rpm, than i am going to test each ignition cell till it gives me max power. And as sed before i will dial it back.

Then temp and atmospheric pressure testing. I think temp is going to play a bigger role than pressure, but we will see. To isolate the variables i am going to test temp at the same location i did the initial map by manipulating the IAT using a heating source. After testing many heat ranges i will determine is the advance decrease per temp range is linear or not so that i can predict all the ranges.

I will then factor in temp and pressure(?) into the ignition map.
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Old 07-30-2012, 04:16 AM   #25
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If you are doing power runs on a dyno you will find pressure makes a very big difference. Serious 2T racers will also change jetting to suit atmo conditions, and changes here are directly related to ignition settings, and of course heat.
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Old 07-30-2012, 05:00 AM   #26
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I am not going to need to change jetting, that is the other half of my project and also the easiest part.

The most difficult thing of a 2stroke is ignition. From what i have read is that as long as the a/f ration stays the same it wont hamper the ignition, but fuel and air temp is directly related to detonation (as well as combustion chamber design, but my bike is relatively modern).

I don't think i will go past 30 degrees advance when at full load (anything can happen, keep it safe).

For testing proposes i am going to ran at 12.5/1 a/f ratio than after logging during real world testing (riding the damn thing)
i am going to lean out my cruising load and rpm and back off of the (less advance) corresponding ignition cell's.

I have to thank you for contributing to my tread Twin-shocker.
If i could i would buy you a beer.
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Old 07-30-2012, 10:09 AM   #27
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If you dont change jetting to accord with atmo conditions when running on the dyno, you will be losing a fair amount of power, but more importantly will have no real idea whether or not changes to ignition are simply compensating for weak or rich mixture rather than making the motor work better.

You will also have major problems if the squish clearance has not been corrected, as this will mean greatly increased piston crown temperature, and increase the chances of detonation, as well as reducing MSV.

Effectively tuning a 2T motor is in many ways far more complex than a 4T, due to the amount of difference that will result from changes in heat/pressure, and is certainly not something for someone without a fair amount of previous experience of this type of work.
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Old 07-30-2012, 10:51 AM   #28
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The second part of this project entails replacing the carb with something more suitable. No more jets to worry about.

Checking the squish clearance is something i was planning to do before i start my project. I was also planning on engine rebuild and setting my PV correctly.
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Old 07-30-2012, 11:45 AM   #29
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If you intend to add direct FI to your motor, you are going to need electronics rather more complex than those you have currently.

Might be better to either take on board the fact you are going to need to spend time getting the fueling right, in order to get any worthwhile results from alterations to the ignition, or think about abandoning the whole project?

Up to now very few people have been able to get injection working properly on 2T motors, and I get the feeling that the only competition application running FI currently is on the Ossa trials bikes?
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Old 07-30-2012, 12:37 PM   #30
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I don't want to add direct fi, i want to add port fuel injection (throttle body injection) fueling is not a big problem i can maintain it at 12.5/1 a/f ratio through out the 12*12 fuel map (closed loop operation) and alter it later after i know in which rpm and load cell i use for cruising.

The biggest problem i had was ignition, because it was an unknown when concerning 3D maps.

examples

banshee
http://www.youtube.com/watch?v=e1WHVVT6d9c

suzuki gt250
http://www.youtube.com/watch?v=_aAfptmI4jU

cr500
http://www.youtube.com/watch?v=TE5ENcMH1ZI
http://www.youtube.com/watch?v=Y91Jms6MyCY

There's also an rd350lc

I did not really want to bring up the fact that i am looking to fuel inject a 2stroke because of bad criticism.
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