ATC70 - CDI Conversion

21100 Views 34 Replies 14 Participants Last post by wes350x, Jan 5, 2014

Z

Discussion Starter · Dec 19, 2008

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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1 - 20 of 35 Posts

BUZZ 50s BROTHERHOOD

· #2 · Dec 20, 2008

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...

Z

Discussion Starter · #3 · Dec 20, 2008

BUZZ 50s BROTHERHOOD said:
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.

gstegman

· #4 · Dec 24, 2008

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

Thanks,

thorwarrior915

· #5 · Dec 24, 2008

gstegman said:
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.

50WHIP

· #6 · Dec 24, 2008

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.

mexicanyella

· #7 · Dec 26, 2008

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.

Bucktorious

· #8 · Mar 29, 2009

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.

Z

Discussion Starter · #9 · Mar 29, 2009

Bucktorious said:
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.

Reactions: 1

fatcaaat

· #10 · Mar 29, 2009

Z said:
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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Z

Discussion Starter · #11 · Mar 29, 2009

fatcaaat said:
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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fatcaaat

· #12 · Mar 29, 2009

Z said:
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.

Z

Discussion Starter · #13 · Mar 29, 2009

fatcaaat said:
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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jrotten

· #14 · Mar 30, 2009

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

thanks

Z

Discussion Starter · #15 · Mar 30, 2009

jrotten said:
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.

jgk200

· #16 · Apr 6, 2009

Z said:
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

Would love to see some pic's Dan!! I'm going to look at a CDI Conversion 70 today thats up for sale in my neck of the woods... If all goes well she'll be mine!! I bought (2) 70's yesterday as well both run but, are alittle rough, My brother is taking one of them off my hands for his son.... Thinking of doing the CDI Conversion to the other one... Thanks for your time!!

Z

Discussion Starter · #17 · Apr 6, 2009

jgk200 said:
Would love to see some pic's Dan!! I'm going to look at a CDI Conversion 70 today thats up for sale in my neck of the woods... If all goes well she'll be mine!! I bought (2) 70's yesterday as well both run but, are alittle rough, My brother is taking one of them off my hands for his son.... Thinking of doing the CDI Conversion to the other one... Thanks for your time!!

I'll have pics over the next 2-3 weeks. I'm mounting up tires and need to clean up the original plastics and treat the original seat and she'll be ready to ride.

BOGGEDDOWN

· #18 · Oct 19, 2013

Hello all forum members i just recieved a conversion kit from overseas ,,, ill introduce myself first My name is Dave im from Newfoundland Canada ,, i have a 1985 honda big red ole faithful and purchased a atc 70 1985 for my 3 yr old last year he can already do donuts on it but she got wet and the points are acting up so i wanted to swap out for the cdi conversion which i have recieved i stumbled upon this site from ggoggling cdi conversion and was reading threw this post which i was trying to find a detailed ie picture thread on the conversion i find it hard to navigate on this site is there anyone that has a link to the conversion thanks in advance happy triking Dave Newfoundland ....

tmas

· #19 · Oct 19, 2013

BOGGEDDOWN said:
Hello .. i find it hard to navigate on this site is there anyone that has a link to the conversion thanks in advance happy triking Dave Newfoundland ....

Hello Dave from Newfoundland.... Check the links below....
tmas

http://planetminis.com/forums/z50-ct70-jdm-monkeybikes/99775-cdi-conversion-possible.html

http://planetminis.com/forums/1973-1985-atc70-trx70/156107-atc-70-cdi-conversion.html

BOGGEDDOWN

· #20 · Oct 19, 2013

tmas said:
Hello Dave from Newfoundland.... Check the links below....
tmas

http://planetminis.com/forums/z50-ct70-jdm-monkeybikes/99775-cdi-conversion-possible.html

http://planetminis.com/forums/1973-1985-atc70-trx70/156107-atc-70-cdi-conversion.html

Thanks for the above links im actually at her right know those two stator screws were in there tight enought too strip out the heads with the phillips i got the top one out came for a smoke and warm up cold day and damp here today im gonna drain off the oil and try to get the bottom one i dont know if you ever used the screw extractor from canadian tire but it saved my a$$ many a time ill attach a link to the tool if anyone ever comes across the problem ,,, wonderful site you have here ill keep you updated on the progress it wont be completed today for i put new rear bearings in there while waiting for the cdi to show up and rebuilt the carb i also have to install a new drive chain im waiting for it was stretched beyond adjustment was gonna pop a link but would probably be to short Thanks
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