Page 1 of 4 1 2 3 ... LastLast
Results 1 to 10 of 38
  1. #1
    Sooo...how much for the 780? stimpsonjcat's Avatar
    Join Date
    Apr 2012
    Location
    Georgia - Lake Lanier - near 6TH
    Posts
    853
    +1
    19

    Alternate CDI device?

    I work for a company that sells automation equipment.

    It occurred to me that the basic functionality of the CDI is simply to detect TDC at the MAG and then fire the 3 cylinders at the proper positions.

    It also appears to advance/retard the timing based on the speed and retards timing on certain failures.

    Is this the extent of it's functionality?

    I am asking as it might be an interesting project to replicate the CDI using a PLC. Heck it might be necessary at some point if spare parts eventually dry up.

    What kind of performance difference is there between some of retarded skis (like my SLT) and the hotter units not made for towing? I was thinking if I did go to the trouble to model and fabricate this, I could add a feature to switch modes from towing mode to performance mode.

    Might be fun to add some temp detection in the exhausts while I am at it, for tuning and alarms. Mount a small display in the flip up storage lid.

    Hmmmm...


  2. #2
    casey67's Avatar
    Join Date
    Sep 2006
    Location
    Lemont,IL
    Posts
    2,571
    +1
    35
    You might want to cut one open to see what's inside.
    I don't think any one found a detailed schematic of what is actually inside a CDI.

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,593
    +1
    1,275
    The timing functionality is basically as you describe.

    The gray wire into the CDI is effectively an A/B signal that tells the CDI which of two possible timing curves to utilize. Some racers would reprogram the CDI so that the gray wire switched between two high performance timing curves, rather than a regular and a retarded curve set.

    There is a several hundred volt Capacitive Discharge (that would be the CD in CDI) circuit in there that fires into each ignition coil. High voltage electronics are tricky to do well. It needs to be able to charge and discharge circa 300 volts into the ignition coils at a rate approaching 100 cycles per second, per cylinder.

    I am sure the CDI can be extracted from the potting compound and reverse engineered. Some of the electronic parts inside might be proprietary to PVL or no longer available commercially.

  4. #4
    johnsonmtz's Avatar
    Join Date
    Oct 2006
    Location
    Mt. Zion Illinois
    Posts
    1,250
    +1
    7
    Interesting idea indeed. As Keith stated, it may be entirely possible to reverse engineer the CDI. Actually, I'm positive it can be done. I'm sure there may be some proprietary components, but if you can determine the functionality of the components you could engineer something to replicate the parts.

    The trick, as Keith eluded to, is to make something that can do the job and be durable enough for a marine environment.

    Obviously we Polaris folks will be a shrinking crowd as time goes on. But there could be a market for parts such as this for the faithful few. It would be more a labor of love for the one making the part (i.e. not a profit center) but could probably at least be a break even venture.

    If nothing else, it would be nice if someone with extensive electronics knowledge would be willing to perform repairs on stators. I recall reading Jetski solutions will no longer repair Polaris products (or is planning to discontinue). If that's the case, I'm sure someone could make a nice little side business for themselves doing this work.

    BTW......is StimpsonJcat the long name for 'Stimpy' from Ren and Stimpy? Just curious.

    KJ

  5. #5
    Sooo...how much for the 780? stimpsonjcat's Avatar
    Join Date
    Apr 2012
    Location
    Georgia - Lake Lanier - near 6TH
    Posts
    853
    +1
    19
    I'll continue to think on this, the discharge data is very helpful. Is there any VA data on the coils?

    Turning little sparks into big sparks can be expensive, but not necessarily difficult. I am a EE (can't spell GEEK without EE!) so don't panic.

    Yes, stimpsonjcat is stimpy's full name. I was a fan of the early shows, not the later stuff. I also used stimpy as my online handle for years of FPS fun.

  6. #6
    fixer's Avatar
    Join Date
    Feb 2011
    Location
    Mass
    Posts
    498
    +1
    20
    I think I have some junk units I could send you if you want to cut one open.

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,593
    +1
    1,275
    Capacitive Discharge Ignitions have been around for decades. Lots of existing design material out there.

    I have no idea how advanced or tricky the design inside the German engineered PVL ignition system is. From the outside it seems fairly straightforward.

    Keep in mind that it took them three design cycles to get it right. Gen I CDI was followed by Gen II CDI, then in 1999 (for the then brand new 1200 engine) they changed the stator coil configuration and released a third CDI design, which we call the Gen III or Update Kit version.

    Reliability is a huge requirement for a Marine ignition system. Lots of electrical stuff the car and motorcycle guys get away with just would not last inside a watercraft hull.

  8. #8
    I'm addicted to Polaris PWC ghostinstallations's Avatar
    Join Date
    Aug 2011
    Location
    Rochester, New York
    Posts
    920
    +1
    28
    CDI is simple, but what makes it complicated in our application is the following:

    -Non linear curve
    -Rpm limiter
    -Pulse activated shutdown

    Not necessary, but in our current CDI:

    -Externally activated rpm limiter
    -Programmable curve
    -On the fly curve shift (+/- 2 degrees)

    Ideally in a replacement CDI, I would like an inverter based CDI to eliminate the exciter coil on our current system (the only real failure point of the stators). If not that, then one simmilar to the gen3 units that have a low resistance, single exciter coil.

  9. +1 by:


  10. #9
    This is how I run a jetski shop in the desert nmpeter's Avatar
    Join Date
    May 2008
    Location
    Elephant Butte New Mexico
    Posts
    6,529
    +1
    1,277
    I suspect there are additional issues surrounding the Polaris cdi..or some offshore company would be cranking them out like mad dogs. They certainly manage to produce seadoo mpems with lots of options.

    Now for just a little food for thought.

    back in the day a converted a honda 400cc automatic transmission motorcycle from a cdi to a standard points ignition for a veteran who couldn't afford to buy a new cdi every year or two (they were notorious crap) Used off the shelf parts from other honda motorcycles.

    ..what's out in the world that _might_ be used in place of the pvl ignition for the various two strokes we'd like to keep running

  11. +1 by:


  12. #10
    Rivrunner's Avatar
    Join Date
    Jul 2012
    Location
    Atco, NJ
    Posts
    46
    +1
    2
    I have thought about this also, I currently do embedded programming on atmel micro controllers (Hobby only) and would like to build up a temp monitor for all three cylinders then display and log temperatures and rpm then be able to download to the laptop, could be useful to help prevent holed piston and tuning. Maybe a winter project.

    The thought of a programmable cdi crossed my mind but reliability is the main issue.
    Your best bet is to unpot one and put a scope on it to see what voltage the exciters are charging the caps at and how fast. You would also need to scope the coils to see the voltage and discharge rate so as not to overheat the coils. Could be done if you have a lot of spare time on you hands. I would also consider doing away with the exciters and run directly from the battery just using the trigger to fire.

Page 1 of 4 1 2 3 ... LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. STEP by STEP - One alternative to building a fast rec ski.
    By philip_gpr in forum Yamaha How To & FAQs
    Replies: 25
    Last Post: 12-11-2016, 06:10 PM
  2. Advent CDI Triple Pipe Curves....what's the best ones?
    By carbuff91 in forum Yamaha PWC Performance (2-stroke)
    Replies: 3
    Last Post: 12-03-2008, 06:53 PM
  3. Diffrence between keyway and CDI advance
    By NeVerMind in forum Yamaha PWC Performance (2-stroke)
    Replies: 5
    Last Post: 06-14-2006, 11:49 AM
  4. COMPACTIVE DISCHARGE IGNITION OPERATION (CDI)
    By ABBOTT in forum Yamaha How To & FAQs
    Replies: 0
    Last Post: 02-15-2006, 10:53 PM
  5. Advent CDI issues
    By RichGPR in forum Yamaha PWC Performance (2-stroke)
    Replies: 14
    Last Post: 11-21-2005, 07:16 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •