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ATC70 - CDI Conversion

This is a discussion on ATC70 - CDI Conversion within the 1973-1985 ATC70 and TRX70 forums, part of the General Talk category; This will be a 2 part thread. I'm going to build up 2 motors for this trike with with CDI's and ditch the points. 1. ...

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    ATC70 - CDI Conversion

    This will be a 2 part thread.



    I'm going to build up 2 motors for this trike with with CDI's and ditch the points.



    1. I picked up a 12V TRX70 CDI engine for $75 from a member here that quit shifting. Upon teardown, the engine had a cracked shift detent arm (see attached) and a bent shift shaft. With $30 of replacement parts and a 108cc kit, clutch and oil pump, she'll be back on the road in the spring.



    2. I'm going to take the existing 1985 ATC engine and convert it to a 6V CDI using the CDI conversion the guy on ebay is selling. Reports have been good for this piece, and at $99 plus shipping, I'll never have to worry about points again. This engine will receive an oil pump, uprated auto clutch and just an 88cc Kit keeping the stock head and carb. I'll rejet the carb and call it a day.



    Once the parts arrive, I'll provide a tutorial of the modications for others interested in converting their points engines to CDI.
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    Re: ATC70 - CDI Conversion

    COOL THREAD......





    But there is a easier way using a jingcheng copy z50/dirtmonkey stator and flywheel as they will fit straight in a trx or atc 70 bottom end...

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    Re: ATC70 - CDI Conversion

    Quote Originally Posted by BUZZ 50s BROTHERHOOD
    COOL THREAD......





    But there is a easier way using a jingcheng copy z50/dirtmonkey stator and flywheel as they will fit straight in a trx or atc 70 bottom end...


    I don't want to go that route. I'll be keeping the Honda flywheel.

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    Re: ATC70 - CDI Conversion

    What is the thinking with converting to 6 volts rather than 12? Where they possibly 6V stock in 85?



    Thanks,

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    Re: ATC70 - CDI Conversion

    Quote Originally Posted by gstegman
    What is the thinking with converting to 6 volts rather than 12? Where they possibly 6V stock in 85?



    Thanks,


    They were 6 volt originally, only now it will be a CDI 6 volt setup instead of the oldschool points and condensor deal. Less finicky, more reliable.

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    Re: ATC70 - CDI Conversion

    Our one buddy used to use a little electronic pickup for chainsaw called a MEGAFIRE .You could get rid of the points and it was like an electronic igntion.He seemed like the only one that it worked right for though and we all gave up on them but he still swears by the megafire.

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    Re: ATC70 - CDI Conversion

    Thanks for the heads-up and effort of doing it, Z; this looks like it will be an interesting read and possibly instructive in my own efforts.



    I bet a 108cc hopped-up ATC70 will be a handful. Maybe a good thing to wear a helmet while operating. But fun all crossed up on smooth, sweeping road curves with soft surfaces, all hangin' off the inside, inside rear wheel just barely liftin'...



    Might be fun to have a set of spare rear wheels with some old-school "flat-track" tires (otherwise known as 18x9.50x8 turf tires) for those dirt and gravel tricks.

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    Re: ATC70 - CDI Conversion

    How did the CDI conversion work out for you? I'm also thinking of using the kit from ebay, kinda tired of working with points.

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    Re: ATC70 - CDI Conversion

    Quote Originally Posted by Bucktorious
    How did the CDI conversion work out for you? I'm also thinking of using the kit from ebay, kinda tired of working with points.


    It's the best modification I've ever done on a 6V engine. Bar None. After full rebuild, the engine started on the 2nd pull and runs as good as any of my 12V CDI bikes. I'm running this on a 88cc BBK with a race head, good exhaust and 20mm carb. Idles perfectly and runs like butter.



    A must have for anyone who doesn't like messing with points.
    schofell84 likes this.

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    Re: ATC70 - CDI Conversion

    Quote Originally Posted by Z
    I don't want to go that route. I'll be keeping the Honda flywheel.


    Ahhh...so you may be the Sensei with all things Honda and Japanese, but you are just a novice in the china world my friend. You cannot run a Honda flywheel on the kits offered overseas...the stator sizing is different from the china to honda...been there, done that.



    Your best and cheapest approach, to be honest, is to purchase just the "thimble" that guy sells and couple that with a honda xr50 complete ignition, including stator and flywheel. Or, you can pop on the Ricky Stator and have lights. Otherwise, you will have to go the normal china flywheel which will be ok once you turn it way down and hope it is balanced.



    Of course, I wouldn't be fred sanford if I didn't try and pawn something off...I happen to have a complete ricky stator plate ignition with a mismatched china flywheel and I pulled my hair out for 2 months before I realized why the motor wouldn't run. If you can wait until I go visit my mom in PA in a month, I can reserve it for you. Just the plate and windings.



    Also, I am sure you know you have to modify the cases so that the pickup clears...

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    Re: ATC70 - CDI Conversion

    Quote Originally Posted by fatcaaat
    Ahhh...so you may be the Sensei with all things Honda and Japanese, but you are just a novice in the china world my friend. You cannot run a Honda flywheel on the kits offered overseas...the stator sizing is different from the china to honda...been there, done that.



    Your best and cheapest approach, to be honest, is to purchase just the "thimble" that guy sells and couple that with a honda xr50 complete ignition, including stator and flywheel. Or, you can pop on the Ricky Stator and have lights. Otherwise, you will have to go the normal china flywheel which will be ok once you turn it way down and hope it is balanced.



    Of course, I wouldn't be fred sanford if I didn't try and pawn something off...I happen to have a complete ricky stator plate ignition with a mismatched china flywheel and I pulled my hair out for 2 months before I realized why the motor wouldn't run. If you can wait until I go visit my mom in PA in a month, I can reserve it for you. Just the plate and windings.



    Also, I am sure you know you have to modify the cases so that the pickup clears...


    Jared,



    Thanks for the post. Let me expand on the comment I made to put my post into context as I made no comment on what was the cheapest or easiest. My comments are were what I wanted to do for this specific project.



    I stuck with the Honda flywheel setup since you can't easily modify an ATC70 stator cover to fit the 12V CDI pickup and flywheel underneath it. There isn't enough metal/meat (in my opinion, yours may differ) to make clearance on the ATC stator cover. If it can be done, it's something that holds little interest for me to go through that much time and effort. And, you'd have to drill and machine the 12V flywheel to fit the pullstarter and shim it out so the pullstart engages correctly and as you noted below, grind the cases for the pickup. Dratv has some brief info on this on his website on how to adapt the pullstart for some of the chinese engines, but it's the same principle.



    For me, it's not worth the trouble or time when a $99 option will get me exactly where I'm going and has excellent reviews with people running these for 2-3 years without a hiccup on the ATC's. I bought mine on ebay and it came as delivered with great instructions 3-4 weeks after I ordered it as promised. It doesn't come with the O-ring or oil seals, but I had those pieces here in anticipation of the CDI conversion coming.



    The piece flat out works. No modification to the wiring harness or 6V coil, no modification to the ATC stator cover, no changing and modifying the flywheel for the pullstart, no modifying the cases and everything looks factory when installed.



    If I wanted a 12V CDI engine in the ATC, I would have built up the TRX70 engine that has all the fixins from the factory in a 4-up 4 speed and a stator cover that matches all the guards and bodywork on an ATC. I'm saving this complete $75 TRX70 engine for a second ATC in the future as my 8 year old boy doesn't need a 108-124cc in his ATC. He'd kill himself in short order and then the Mrs. would have my hyde.



    As it is now, with the throttle limiter almost fully bottomed out, he can still lift the front wheel with the 88cc kit and a snap of the throttle.



    I'll never claim to be an expert on the chinese parts and will leave the mixing and matching up to all of you who have the time and desire to spend hours on end in the workshop doing the necessary R&D helping others save time and effort along the way. I don't have the time nor the desire to begin down that path.



    Keep up the good work with the engine R&D as it greatly benefits the PM community.

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    Re: ATC70 - CDI Conversion

    Quote Originally Posted by Z
    Jared,



    Thanks for the post. Let me expand on the comment I made to put my post into context as I made no comment on what was the cheapest or easiest. My comments are were what I wanted to do for this specific project.



    I stuck with the Honda flywheel setup since you can't easily modify an ATC70 stator cover to fit the 12V CDI pickup and flywheel underneath it. There isn't enough metal/meat (in my opinion, yours may differ) to make clearance on the ATC stator cover. If it can be done, it's something that holds little interest for me to go through that much time and effort. And, you'd have to drill and machine the 12V flywheel to fit the pullstarter and shim it out so the pullstart engages correctly and as you noted below, grind the cases for the pickup. Dratv has some brief info on this on his website on how to adapt the pullstart for some of the chinese engines, but it's the same principle.



    For me, it's not worth the trouble or time when a $99 option will get me exactly where I'm going and has excellent reviews with people running these for 2-3 years without a hiccup on the ATC's. I bought mine on ebay and it came as delivered with great instructions 3-4 weeks after I ordered it as promised. It doesn't come with the O-ring or oil seals, but I had those pieces here in anticipation of the CDI conversion coming.



    The piece flat out works. No modification to the wiring harness or 6V coil, no modification to the ATC stator cover, no changing and modifying the flywheel for the pullstart, no modifying the cases and everything looks factory when installed.



    If I wanted a 12V CDI engine in the ATC, I would have built up the TRX70 engine that has all the fixins from the factory in a 4-up 4 speed and a stator cover that matches all the guards and bodywork on an ATC. I'm saving this complete $75 TRX70 engine for a second ATC in the future as my 8 year old boy doesn't need a 108-124cc in his ATC. He'd kill himself in short order and then the Mrs. would have my hyde.



    As it is now, with the throttle limiter almost fully bottomed out, he can still lift the front wheel with the 88cc kit and a snap of the throttle.



    I'll never claim to be an expert on the chinese parts and will leave the mixing and matching up to all of you who have the time and desire to spend hours on end in the workshop doing the necessary R&D helping others save time and effort along the way. I don't have the time nor the desire to begin down that path.



    Keep up the good work with the engine R&D as it greatly benefits the PM community.


    I mis-read...I thought you were going for a 12v conversion...Just as an FYI, it is important to note a China 12V stator is incompatible with a Honda Flywheel.



    The 6V conversions you are talking about do work great...my buddy has been running one for quite a while.



    That being said...you've made an excellent choice.

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    Re: ATC70 - CDI Conversion

    Quote Originally Posted by fatcaaat
    I mis-read...I thought you were going for a 12v conversion...Just as an FYI, it is important to note a China 12V stator is incompatible with a Honda Flywheel.



    The 6V conversions you are talking about do work great...my buddy has been running one for quite a while.



    That being said...you've made an excellent choice.


    We'll find out in due time when the kids are beating the crap out of it. I found a great place to hide the CDI box on the inside of the ATC frame using an existing bolt hole.



    I'll take some detailed pics for the ATC crowd should anyone want a simple solution and makes a very smooth running engine.



    For my 12V conversion. It's going to be pretty straight forward. Rebuild the TRX70 lump and bolt it in. $75 plus the cost of the rebuild parts. I got it with the wiring harness, coil and CDI as well. Bolt and go baby. Tim was kind enought to hook me up with a better flywheel as mine was rusted to all hell.



    Keep up the good work!



    Dan

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    Re: ATC70 - CDI Conversion

    will that 6v cdi conversion work on my 82' z50?

    thanks

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    Re: ATC70 - CDI Conversion

    Quote Originally Posted by jrotten
    will that 6v cdi conversion work on my 82' z50?

    thanks


    Email the guy in the ebay auction and give him the year and Serial number of your engine and he will tell you. It works on most 6V 3 speed engines but you'll need to clarify with the seller. It must have the S crank or 3 speed semi-auto crank and flywheel. He'll need to know if it has the Mitsuba or Hitachi flywheel.

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