Bosch Points Ignition to CDI Conversion?

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Armilite

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Is there anyone messing around with the Rotax Bosch Points Ignition to Nippon Denso CDI Conversion or Bosch Points Ignition to Ducati CDI Ignition, or Bosch Points Ignition to this GY6 Scooter Type CDI Ignition?

Old Way to convert Bosch Points Ignition to Nippon CDI was to replace Top Bosch Coil with Top Yellow Nippon CDI Coil off the Old Horse Shoe Stators and the reindex the Flywheel using a cotter pin.

New Way, by RMS Stator for the Old Skidoo/Rotax 250 Type 247 Singles is to use the whole Horse Shoe Type Stator setup and just drill New Mounting Holes to mount the Yellow Coil Level. Those Old Standard Singles are rated at 5500rpm, so don't work on the other High Performace TNT & Blizzards that are rated at Higher 6500rpm, and 7500rpm. IF, they used a Slot Instead of a Single Locating Hole they could probably be made to work. I still have to get me a Rotary Table so I can Mill one of them Stator Plates. RMS is using a different COMBO Coil/CDI Box, looks like a Newer one off maybe an ATV or Scooter, but the Horse Shoe Stator looks the Same as the old Skidoo/Seadoo Horse Shoe Type.

I have never seen anyone Adapt a Newer Ducati or these Cheap GY6 Type CDI Conversion's done to a Rotax.

Bosch Points Coil is mounted at a 45 Degree Angle to the right like in the last Photo. The Horse Shoe Type Coil is mounted Level across the Top as in the photo. The Skidoo/Rotax Stator Plate Bolt Pattern used, is based on a 100mm/101mm 36 Bolt Hole Pattern. So 360/36 = 10 Degrees for Center Line of Stator Plate Studs/Bolt Holes.

Seadoo's and Skidoo's used these same Horse Shoe Type Stators, as did some other Snowmobile Engines. Most CDI Ignition use only (1) Ignition Map, Skidoo/Rotax Nippon use's (2), that is Why they Idle better than Ducati!

Now I'm not an Electronics whiz by any means and I'm mainly just interested in now for what we can do with using these Stock Rotax Bosch (4) Magnet Stock Flywheel without doing any Re-Keying it and just using maybe these Cheap Horse Shoe CDI Stators on ebay. The Seadoo Horse Shoe Type ($32-$45) is way Cheaper than the Skidoo Horse Shoe Type. They may have different Type Connectors on the Wire ends is all, andmaybe different Colors to confuse us. You can use the aftermarket Nippon CDI Box usually ($40-$60) and Nippon Type External Coils($30-$40).

But, if we can find a way to use these real Cheap GY6 CDI parts, like the CDI Box, CDI External Coil, Spark Plug Wire, would be great to keep the Cost down. The GY6 Crank/Flywheel Tapers and Stator Plate used are different Size from Rotax's, as is the GY6 Crank Stokes are Smaller 41.4mm and 57.8mm. Can a Skidoo/Rotax Stator Plate be Designed to use them Parts, Yes.
 

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Armilite

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My Rotax 277 Case's come Drilled & Tapped with (4) Holes for using both Bosch Points Stator Plate and the Nippon Denso CDI Stator Plate. The 1980-82 277 Bosch Crank MAG End Taper's were different from Nippon CDI Cranks. They switched from 1983+. So 1980-82 277 Bosch Flywheel is different from 1983+. This 3rd photo on Top right is Horse Shoe Stator off I think a 583 I got with a parts engine.
 

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Armilite

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Old Skidoo/Rotax Singles had (3) Studs/Bolt Holes for the Bosch Points setup. It's my understanding all 1980+ Rotax 277UL's that were made up to around late 90's had Bosch Points. Scat Hover Craft 277's 1983+ had Nippon CDI. The 1983+ to around 1999 Skidoo 277F's had Nippon CDI and then were Swtiched over around 2000 till 2008 to Ducati CDI when they were discontinued.

The Smaller Rotax 250 with CDI is still made today in Russia under the RMZ Brand, similar to the Skidoo 250 Type 253 that was made here for US/Canada.

The Rotax 185 is still made for Water Pumps, and has been upgraded to CDI and use's a Nikasil Cylinder.
 

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Rincewind

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Hiya. I'm hoping to convert a Rotax 532 from points to CDI. Are there kits available anywhere or maybe I have to eat a system of a SkiDoo of some kind?
 

Armilite

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Hiya. I'm hoping to convert a Rotax 532 from points to CDI. Are there kits available anywhere or maybe I have to eat a system of a SkiDoo of some kind?
===================

Nobody that I know of is offering a kit for the 532UL. Airscrew might still offer to do it, or figure it out yourself what you need to do.

Do you have a Photo of your Points Stator and Flywheel? With your Piston closest to the Points End at TDC, what Angle is the Flywheel Key? Consider TDC as Zero Degrees!
 

JonathanHarris

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I am also in the same boat, just rebuilding an old low hours Rotax 532 points and want to convert to CDI. I bought a Skidoo set up ( Horse Shoe type) but the flywheel does not fit the shaft. So please could some expert step forward and let me know how to use my existing Bosch flywheel to power the ND system, gather I have to move it and drill for a cotter pin, but worried how much to move it to get the engine to run and then fine tune it, has anyone done this? Alternatively there may be an aftermarket 12v system that could be utilised with an external trigger?
seem to have various old 583/670 types but not sure if the Bosch flywheel will work? Here is a photo of the two flywheels and the 521 “horse shoe” stator.40C94F3E-780B-4D50-8913-2FB5328C7D74.jpeg40C94F3E-780B-4D50-8913-2FB5328C7D74.jpeg
 

n3puppy

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let me know how to use my existing Bosch flywheel to power the ND system, gather I have to move it and drill for a cotter pin, but worried how much to move it to get the engine to run and then fine tune it, has anyone done this?
First things first - measure the diameter of the magnets on both flywheels to be sure they are close. (Coils on stator clear magnets. )

Long time ago I helped a friend do an Airscrew conversion on a 277. He bought the kit and did it himself.

STRICTLY FROM MEMORY -long story short
You want the engine to fire at TDC with hand crank rpms. Timing curve of CDI takes care the advance when the engine starts running.

Bolt the flywheel on without the woodruff key (tapered shaft will hold it in place)
Set a piston at TDC
Mark the case and flywheel so they line up at TDC.
Spin at about 300 rpm with a variable speed drill
See how far apart the marks with a timing light.
Pull the flywheel and rotate about the same distance
Bolt back on, Re-mark flywheel at TDC and try again.
Keep doing until you have timing at TDC.
Then when you run the engine - use the slots in the stator to set the final timing at running rpm

When you get the timing correct - drill the crank for roll pin using the flywheel keyway as a guide.

Like I said- all from Memory - Airscrew might still sell kits - WITH instructions
 
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JonathanHarris

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Thank you very much, great info. Yep, the inside diameter of the magnets on the flywheels was within 1 mm. It would be interesting to know the position of the flywheel key way versus the crank key way when finally set up as this would give a good starting point. I will try ringing Steve Beatty at Airscrew.
 

n3puppy

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It would be interesting to know the position of the flywheel key way versus the crank key way when finally set up as this would give a good starting point. I will try ringing Steve Beatty at Airscrew.
One thing to ask if you get ahold of Steve - can't remember, but seems like there may be a preferred place to have the stator when doing all the TDC trial and error.
Bolts in the slots. - full advance, full retard, in the middle? Would think there is a preferred starting spot so when you do final positioning, there is adjustment in both direction for future tweaks.

Also - His kit just had the coil to replace on the points stator - not a whole stator.
Doo sleds had a couple different CDI ignition coils over the years, single and double stacked coils,
Different timing curves - and CDI boxes. Would be interesting what he used and why (can't remember)
Hard to tell from the picture - but looks like yours might be single coil?

B14FD585-8D41-4316-BFD6-1B9940AAC59F.jpeg
 
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JonathanHarris

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I spoke to Steve Beatty and it is as you said. He uses an speed adjustable electric motor to spin the engine and gets it up to a good rpm to check advance etc. He thought you might need 600rpm for this basic strobing exercise.
Basically spin it ( I will modify a 1/2 unf bolt and lock nut in the pto shaft), use chalk marks on the flywheel ( start anywhere) and fine tune it until you have moved the flywheel that it is firing at TDC. Presumably with the adjuster slot mid way. Once you are happy, use a 5/32 drill to drill in 5/8“ along the key way. Cut 5/8 off the drill shank and use that as the cotter pin.
I think I might mount the flywheel and stator plate on the lathe first to make sure it all works! It will also enable me to get a rough idea of the position.
He mentioned that it all started with the Skidoo Blizzard 5500 that I think was points, and then moved to CDI.
 
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