Rotax 185 CDI Conversion...easy!

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Postby rayjb60 » Mon Jan 10, 2005 11:10 am

I am converting the Rotax 185 ignition from points to CDI.

Reasons:
-No more points fouling or needing adjustment. More reliable, No moving parts, No wear, No changes in timing, once set.
-Smoother running at all speeds, due to built in electronic spark advance curve.
-More powerful, reliable spark, apparently resists plug fouling better.
-More power, less vibration from rough running, via spark advance curve.
-Slightly Better fuel efficiency.

I bought the CDI conversion kit from Wildfire for $299.50 USD.

The kit contains a new flywheel, armatureplate/stator assembly, CDI/coil box and a bag of nuts, bolts and a connector.
The wires coming out of the CDI/coil unit from left to right are Ground(red wire), Ignition Kill(Red connector), Spark plug wire, and the wire going to the Stator/armature.....simple!!!!
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(Revision 01/01/05: The flywheel is different in that the key and the 3 holes are aligned to produce about 25 degrees of advance over the original, so I used the kit flywheel after all. You could however advance the armature by that amount instead with a bit of drilling)(note the difference in posiltion of the little hole near the center of the hub...its a reference mark)
There is no geometry change to the flywheel/starter assembly, so NO modifications are required....its a drop it in and run it.....EASY!!!!!
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The armature plate is also identical to the existing Rotax armature plate, so the only new parts that are required are the CDI/coil unit which I found for $70 USD and a new stator coil which could probably be had for $20 USD, but I have not looked for a source yet.
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Bottom line is that the conversion should only cost about $100 USD per engine, just as I suspected all along.

I will assemble the engine with the conversion and try it out and let everyone know how it runs.

More pictures and details to follow.

If you have any questions let me know. I will sure be nice not to have to worry about the engine as much.
<H5>Nothing is impossible...Even the word tells you Im-Possible!!!</ H5>
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Postby Guest » Mon Jan 10, 2005 12:51 pm

You say there is no difference between the old flywheel and the new one supplied in the CDI kit. Are you 100% sure of what you are saying here ? According to the information posted on the Wildfire site the new flywheel is equipped with a magnetic pick-up. Are the old flywheels equipped with pick-ups ?

From the Wildfire site:

"The upgrade to the electronic ignition system will eliminate the need for regular maintenance associated with breaker points. The electronic ignition system uses a magnetic pickup located on the flywheel, which when passing over a certain point on the stator will induce a high voltage, therefore causing the spark plug to fire at the proper moment."
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Postby Guest » Mon Jan 10, 2005 2:06 pm

Ray,

If all parts look identical, then maybe the best thing for you to do is to simply remove the points and condensor and bolt up the CDI unit and try it with all of our existing factory parts. This will give you the answer you need. If it works then great, if not then you'll know you may need more than just the CDI unit itself.

Try one part at a time to find out the minimum parts requirements that came with your complete kit from Wildfire. CDI unit first then the flywheel then the stator etc...

Keep us posted.
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Postby rayjb60 » Mon Jan 10, 2005 3:25 pm

I was also wondering about a magnetic pickup from the flywheel, but considering what they sent me and the installation details, there is no mention of this pickup or any kind of alignment that would suggest one exists.

I examined and made measurements of the new flywhell with a caliper to see if the magnets where different length or shape, or placed at different location on the circumference, but I found no differences.

There was also no lead provided from the CDI unit itself to plug into anything else.

There is only a ground, ignition kill and stator output into the CDI unit.

I know that CDI units also usually have a lead for the magnetic pickup, but there is no mention of it what so ever, in the KIT or instructions.

I am assuming that the stator pulse itself is the trigger for the coil, with the appropriate delay or advance via the electronics, for the detected rpm.

It makes sense to me that a single cylinder 2 cycle engine would only need to fire the spark once per revolution, and make a sensor unnecessary, but starting my Rotax up will confirm it absolutely.

I'll keep everyone posted on my progress.

Im 99% certain that this is good news for Rotax owners wanting to upgrade to CDI at minimal cost (Under $100 per engine).

The only unknown at this point is the new stator coil that resides under the flywheel.

The ignition parts are Ducatti from Italy, so im sure with a bit of checking around we will be able to figure this out part numbers and a source.

I found a Ducatti parts source for scooters in California so far.
Ducatti CDI/Ignition Coil
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Postby Guest » Mon Jan 10, 2005 4:56 pm

Ray,

Look all over the CDI unit for a part number. If it's Ducatti, it should have one somewhere. This will be invaluable to the group if this pans out and the only need is to add this CDI unit and nothing else.

good sleuthing
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Postby Guest » Mon Jan 10, 2005 8:05 pm

I'd try the old flywheel. If it works then I would be looking for a refund.
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Postby lazair3ca » Tue Jan 11, 2005 8:29 am

Ray,

I'm really pleased that you have taken the initiative to try ou the new CDI ignition. One of our new local Lazair owners had decided to convert to CDI and we are supposed to meet today to do dome preliminary work before buying one unit and doing the conversion. You may have saved us hundreds of dollars if the old flywheel works and we can find the Ducati parts. We have a local Ducati dealer and I will check out the supply if you can give me the part numbers.

I have a couple of questions:
The wire marked to coil (green) is that equivalent to the old red lead which was called the lighting coil? Provides 6 volts AC for a light or other applications. It looks like there is only one lead from the coil. Perhaps the green wire is a rectified output from the coil?
How do you set the timing? The old way by rotating the disk? What do you set it to? How do you measure it? (That is all one question relatied to timing!)

We were going to charaterize the engine before doing the conversion. This will help us select a good engine for the comparison. If we try to convert a pig we will still have a pig.

I was thinking that if we could qualify the improvements we will be able to justify the cost. But if you can bring the cost down to under $100 it will be an easy decision. I have a test stand so we can do some static measurements like lowest Idle RPM, Max static RPM, and perhaps thrust if we can borrow a load cell. I'm interested in your report on the smoothness and the advance/rpm curve if you have them.

We are looking forward to your test results.

Bill
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Postby lazair3ca » Tue Jan 11, 2005 8:34 am

After taking a better look at the wiring diagram the green wire is the coil connection and there is no lighting output. One functionality has been lost. We use the red wire for our tach connection. I guess we will have to go to an inductive pickup on the plug wire like the Tiny Tach uses.

I assume the large Aluminium box is for shielding Have you found a convient place to mount it?

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Postby Billm » Tue Jan 11, 2005 2:38 pm

One easy way to make a load cell is to take a common pneumatic cylinder, fill it with oil and put a pressure gage on where the air is supposed to go in. I have used this many times and it works really well.
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Postby Guest » Tue Jan 11, 2005 2:57 pm

Fun in progress ! YeeHaww !
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