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dt175 cdi help ...


steptoe1111
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hey guys how is everyone great I hope

I thought I broke a piston skirt or a ring and it got stuck in the port or something, cause the engine locked up,   but I turned out one of the screws holding my stator plate on had come loose and was tumbling around in there,  unfortunately it smashed two of my flywheel magnets

it was a mk2 flywheel with the four slots I had put on a "78" motor  cause I blew a coil on the old stator ,    any way I got another coil off a friend of mine and will have to put that back in there  so I will be running the stator with the low and high speed coils wich requires the 7 wire cdi wich got damaged when the high speed coil blew     

I did some research and found out that the high and low speed coil operate as one coil,                    so could I possibly run a 6 wire cdi on it by connecting those two wires together   without blowing it  

  (ive forgotten what the ohms reading are for those two coils I know the high speed is 13ohms and the low speed 4or 5 I think but because those two coils are wired up in parallel according to ohms law you can subtract the value of the low speed coil from the high speed coil and of the top of my head should be within ball park of what the single coil on the later mk2 stator should be  9ohms, so in theory it should work  

unless the 7 wire is CDI type      and the 6 wire is TDI type ?

if it wont work I was goin to build a simple diy joby     

is the engine speed  timing advance controlled by the cdi  or ive heard some engines use something built into the triggering coil 

if the timing is operated by the cdi   I will need to build this  can be done for around 10bucs  and has a micro controller that will program a  variable time delay  on the trigger coil that  to operate the advance and  retard   

this site here have the diagrams for what I intend on building if all else fails  it has the simple cdi circuit plus the computer controlled advance circuit      http://www.sportdevices.com/ignition/ignition.htm#CDI  

 

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Dont know enough about electronics to argue the details.

There may be more to it but if it is that easy and you can use a 7wire mag with a 6wire cdi it would be good info.

Cant help thinking your missing something. Fkt if i know what though.

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yeah me to mate

maybe im thinking to much into it,

and should just hook it up and see what happens and post the results ... 

 I mean I got  2 X engines that are now cactus..... and for what the bikes are worth over here I could buy another one complet running for the cost of 3 magnetos or cdi units      

I tried soaking the old cdi in methel ethel keytone  "MEK"   for a week  two see whats goin on inside the 7 wire cdi but.....35 year old cured resin is preety hard to dissolve 

ill hook it up like I said above tomorrow and post the results :)    

that computer controlled timing advance and cdi kit might be the go I think should work on any thing with an ac altanator providing 0-300volts a/c   pluss provide 32 degrees of advance

the micro controller can be had on ebay for a couple of dollars and every thing else should be avail at the local electronics store

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played around a bit with it this morn by joining those two coils gave me 6ohms      but did not match the 10ohm the later sorce coil mesures ,  

       so no I don't think you can run a 7 wire stator off a 6 wire cdi ,

but you can run a 6 wire stator with the earlier two slot magneto  I found out :) 

the timing marks on the 6 wire stator don't match, up  so im going to have to ballpark the timing to get  it running and then put a light on it and time her up   

"and I actualy put some lock tight on the stator screws this time"

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well were going again guys,       here is a pick of the magneto I smashed the magnets in,   just had to be bad luck to do this amount of damage  people spin there stators all the time and never had or seen this         any way had to mix and match some parts,  little bit of stuffing around but all worth it in the end ...        any way spent the last hour making this ........ hope this  helps others  fix or understand more about there ignition timing  aswell  IMG_20151222_115930_1_zps2vb0mla3.jpg

(stator screw fell out and  jammed in the coil gap shatterd two magnets)

  late model 6 wire stator will run on the early magneto with no probs at all very nicely,    

  but new slot locations need to be drilled in the stator to find tdc,

firstly.... I used a dial indicator and measured the piston at 1.8mm BTDC,   because im using the original flywheel the  marks line up with the casing    pull the spark plug out connect it back to the lead and rest it inbetween the fins on the head this should ground the plug IMG_20151228_164033_zps32sbtg30.jpg

secondly..    get your timing light out,   you will have to run it off a separate power source like a spare 12v batt,      put a 19mm on the flywheel nut  connect it to a cordless drill and spin the engine counter clockwise

  (you will need atlest 200rpm to create a decent spark to fire the timing light) IMG_20151228_143003_zps1hmt4pnw.jpg

  when it does flash you need to find your     flywheel TDC mark   (wich could be anywhere in most cases)  ,  mark the casing in relation to where TDC on the flywheel is showing under the timing light  flashearly%20late%20mag%20text_zpsfurcg2vz.jp (the diference in alingnment between the two mags notice the diference in the keyways between the two )

 thirdly.... once that is done and your new timing mark is there, set the original timing marks back to factory and mesure the distance from you factory TDC mark to the one you made just before  with the strobe light,

       this will tell you how far your stator is out  and has to be adjusted!   , it pointed me to where some factory scribed holes were located  (they obviously used the same plate on lots of diferent models and drilled them accordingly)    "as did I"       when I rechecked the timing it was dead on ;)     

 i  dident need to but............... I like to a have a  little bit of adjustment....  so I sloted em     gugbj_zpsffqvyhmy.jpg

THIS IS VERY ACURATE

  going by eye mine was fireing at 140 degrees BTDC         and kicking back when turned her over so this is why I  leave the plug out so theres no compresion  .....     "also means no broken ankles or  kickstarters from kick back   or bike screemin off from under you backwards ....... although that would be quite funny to see

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Lot of hard work but very satisfying when it actually runs, well done you. :thumb:

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