modified cdi and cr 80 coil

Discussion in 'High Performance Bicycle Engine Tips and Motorized' started by damo99, Apr 18, 2011.

  1. dracothered

    dracothered New Member

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  2. DaveC

    DaveC New Member

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    Just about any single lead coil would work. I think even a car raceing coil would work, too, as long as it has the same wireing. Of course, then again, who needs a coil as big as one of these engines...

    zpt
     
  3. k.mah

    k.mah New Member

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    awesome! thanks!
     
  4. ivan H

    ivan H New Member

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    Hi, thats exactly wot u want. The CR80 coil gives a really hot spark, better than most of them. The lead from the free end of the charge caps in the CDI goes to the spade terminal on the coil. The earth lead from the CDI goes to the core of the coil with a large eye connector. Cheers
     
  5. k.mah

    k.mah New Member

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    Just put mine together tonight, tested it, no spark. Are the charge caps ( i rhink thats what they are....2 biggest things on the board) directional? I'll be re checking all the connections and orientations in the morning.
    Also, if jumpers 4 And 5 are left totally open, will you get any spark? I'll be jumping them to jag settings but would just like to narrow down what my problem is.
    Thanks for the help in advance!
     
    #285 k.mah, Mar 5, 2013
    Last edited: Mar 5, 2013
  6. k.mah

    k.mah New Member

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    Found my answer about the scr on page 27 :)
     
  7. ivan H

    ivan H New Member

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    Glad u found the problem easily. Yes the SCR (silicon controlled rectifier) has a cathode (K), gate (G) & anode (A), & must be oriented correctly, as must all diodes & the 3 tanalum timing caps (the + marked legs go to earth). The large charge caps & all resistors are not polarized & can go in either way. Cheers
     
  8. k.mah

    k.mah New Member

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    my scr was reversed, i built the circuit in mirror image to the diagram, but everything seems to still be in the correct orientation, +'s to earth on the timing caps, and double checked the diodes...but still not getting spark.
    I do have the 47 and .47timing caps going from the same hole to the ground (got tight on space and figured if they were in the circuit anyways, it wouldnt make a difference, but i may be wrong.
    On a side note, what does jumper 2 do? I searched a bunch but am still blank on it
     
  9. ivan H

    ivan H New Member

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    Hey guys, if u read thru this thread & the thread about adjustable timing magnets u will find several warning on the dangers of running to much advance. These warnings r 4 good reason, u can easily hole a piston top, do big & small end bearing damage etc by having the spark too advanced. In this & the "roll ur own CDI" thread I have given a couple of ways to know if the spark is detrimentally advanced, but if u r running advanced spark & r unsure u should pull the jug & piston & view the underside of the piston crown. If all is ok it'll be the normal alloy color with an oil coating. If however, it shows black carbon deposits on the underside of the crown, u r running too much advance. The black carbon deposited is burnt oil resulting from excessive heat. Back the timing off. It doesnt take long to pull the jug & piston to check & is much better than replacing ur engine. Have fun. Cheers
     
    #289 ivan H, Mar 5, 2013
    Last edited: Mar 5, 2013
  10. dracothered

    dracothered New Member

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    Print off a new copy of the circuit and go through it part by part and make sure they all connect to the right parts in the circuit. As you trace through the circuit use a highlighter marker to trace the circuit as you check the connections. Also make sure you don't have any shorts that connect two areas that are not suppose to be connected.

    JP2 is for timing.
     
  11. ivan H

    ivan H New Member

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    Hi, if u google "simple SCR test" or "how to test an SCR", u'll find several simple ways to test ur SCR (out of circuit) with a battery & light bulb, to make sure it aint fried, tho i dont think it would be, but u can check to make sure. The jumper 2, when added in steepens the retard curve. Cheers
     
  12. k.mah

    k.mah New Member

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    found an easy test and took the scr off the board. works great! thanks for the advice!

    Went over the entire board double checking that my circuits were correct and that the orientation of anything with polarity was also correct. im getting more solder tomorrow and will be going over everything that needs to be linked together, then using a dremel in the areas that are supposed to be clean to guarantee there are no shorts. hopefully this will produce spark!
     
  13. dracothered

    dracothered New Member

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    If done per the drawing and nothing is shorted, open (ie: no connection) or was put in the wrong way it should work right out the gate. Check all the connections and make sure the jumpers are in correctly also.
     
  14. k.mah

    k.mah New Member

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    GOT IT TO WORK! I had every rectifier backwards, on the ones i bought have the silver marking on the correct side....but also had a diagram with the arrow and + going in the opposite direction.

    A note to all those going to build these....go by the diagram, the silver strip on the rectifier needs to match your circuit same as the diagram

    SO HAPPY ITS WORKING!!! :D
     
  15. dracothered

    dracothered New Member

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    Congrats... happy motoring brnot
     
  16. k.mah

    k.mah New Member

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    Is it possible to use a 0.47uF 50v Tantalum for the one with the jumper? I somehow lost my spare 35v and the local shops only have either 50v or 100v.
     
  17. dracothered

    dracothered New Member

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    The 50v will be just fine in place of the 35v. Going higher in voltage rating here will not hurt a thing, you just don't want to go lower in voltage.
     
  18. k.mah

    k.mah New Member

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    Awesome! Thanks Much!

    The cdi is working GREAT!
     
  19. dracothered

    dracothered New Member

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    I updated the circuit diagram to show what JP2 does and put an optional kill switch in with a note about the stock kill switch position. Hope this helps all that will build this.
     
  20. flatsteve51

    flatsteve51 New Member

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    Can any body tell me where to find 760 ohm resistors. It's the only part I can't find. Would a 750 ohm work? Thanks for all the info I'm looking forward to building this
     

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