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Brand New CDI for CB400T/CM400T/CM400E/CM400C/CB450SC

Parts came today, soldered it up. Will have to adjust the footprint to be slightly longer for C5, which I kind of figured, but it fits.

I stupidly ordered one of the 1M AEC rated resistors, so I used two 1M 1W resistors out of a resistor pack. They're a bit larger in footprint, so that's why R12 and R13 are standing funny and are blue. Will work fine for testing, I just prefer spending the extra 5-10 cents to get AEC/automotive grade components. Digikey doesn't have 350 ohm thermistors and I don't want to buy NOS, but they do have them in 330 ohm. This 20 ohm difference should be negligible. If it is a problem, then I'll have to add a 20 ohm resistor in series on the board. But we're talking about a 6% variance and the original stuff in this circuit was either 5% or 10% rated so I'd be surprised if it changes anything.

After I was done soldering it up tried to do a bench test on my DVM and wasn't getting much readings. I tried the Sanwa tester that Jim gave me a while back and happy to report the resistance readings are correct, all are on the low end of the scale, practically dead-on. The only one that was different was B/W didn't always have the readings, but I recall having this same problem on rebuilt CM400A CDIs and is probably of no consequence.

Will ship it out tomorrow for Jim to test.

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So, out of curiousity, what’s the day job? You keep saying that you are not an EE… however, this is by far the most thorough job I have seen to date on something like this. And, you are just one person. Pretty amazing to some of us watching. I will gladly order one for my 82 CM450E once they are ready.

I applaud your work.
 
Kentonius said:
So, out of curiousity, what’s the day job? You keep saying that you are not an EE… however, this is by far the most thorough job I have seen to date on something like this. And, you are just one person. Pretty amazing to some of us watching. I will gladly order one for my 82 CM450E once they are ready.

I applaud your work.
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Years ago I did auto body mostly paint work, but the past 6 or so years I've been doing software development. I write software for Linux-based minicontrollers in C++ for the controller panels for large screw compressors that are used in the food refrigeration and science industry. The EE friends I have access to is the hardware engineer who works on our team and I have a friend who lives on the other end of the US who actually is a full-time EE. That guy worked on the phased array antenna stuff for Starlink.

I've been a hobbyist since a kid. It kind of all started when I got my ham radio license when I was 12 and we were going on a car trip and I wanted to take the radio with me but needed an adapter cable. My dad showed me how to solder my own cable and I've pretty much been into electronics repair ever since.
 
Maraakate said:
Years ago I did auto body mostly paint work, but the past 6 or so years I've been doing software development. I write software for Linux-based minicontrollers in C++ for the controller panels for large screw compressors that are used in the food refrigeration and science industry. The EE friends I have access to is the hardware engineer who works on our team and I have a friend who lives on the other end of the US who actually is a full-time EE. That guy worked on the phased array antenna stuff for Starlink.

I've been a hobbyist since a kid. It kind of all started when I got my ham radio license when I was 12 and we were going on a car trip and I wanted to take the radio with me but needed an adapter cable. My dad showed me how to solder my own cable and I've pretty much been into electronics repair ever since.
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Did you ever build a Heathkit radio from a kit ? :)
I used to see them advertised in Popular Science.
 
bilbikek411 said:
Did you ever build a Heathkit radio from a kit ? :)
I used to see them advertised in Popular Science.
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No, I've repaired Heathkit stuff for myself and other people though. I'm fairly young compared to the average ham. I'm 34, so Heathkit was already done by the time I was born. I do have some decent gear from the 60s and 70s though that I've fixed. Hi-fi: 1960s Trio W45 (Early Kenwood), 1965 HH Scott LK-60, 1962 Empire 298 Turntable, Heathkit Speakers (needed crossover repaired and blew a tweeter out on one of them). I do have one good piece of vintage ham radio equipment: mid-70s Yaseu FT-101E. Got that one really cheap because the final amp tube was shorted in it and re-capped the entire unit. Works great. Funny enough, they are still prized for shortwave/HF reception because they are very sensitive receivers. Still consistently rank in top 10 by various places after many years for sensitivity, beating out literally $10,000 radios.

Earlier I posted a picture of the Heathkit Capacitor Checker testing the values of the capacitors used in the CDI. That's another one I bought broken and got working again.
 
The CDI got here yesterday, Monday, and is now installed on the 1978 CB400T1.
Boring details: 84 degrees, 41% humidity, non-ethanol 96 octane fuel, NOS stator, engine has never been apart other than maintenance items. NGK D8EA plugs, new plugs end caps, original coil.
Here's the first cold start.
https://youtu.be/4rw3liYhtpE
and the hot restart
https://youtu.be/hmwMAGEXxmM

I get a Homer for trying to start in gear!:lol:
 
Some photos. This is the Rex's unit
RIMG0169.jpg
The aluminum plate bolts to the frame using the original holes. The CDI is then zip tied to the plate. The size and mounting require removal for a valve adjustment.
Rough comparison of Frank's board vs. Rex's unit
RIMG0170.jpg
The only mod I had to make was an adaptor harness to go from the plug to bullet connectors. 1978/79 CB400t 1 & 2 used bullets and everything else uses the plug.
RIMG0175.jpg

Taped to the wiring harness ready for some road testing and timing advance checks
RIMG0173.jpg
 
Also, I'd say if it survived that spin up around 1:28 then it sounds like the advance timing is working and also higher load. If I had the wrong component values very far off it would have popped right there. Really cool to see this running as this one was a total stab in the dark for me. Been sitting around nervous today waiting to hear if it worked or not! :lol:

In regards to the blue/white on the 78s... I think going forward I'll have to either add an adapter as an add-on during order time or have you specify at order that it's for a 78? Not sure what would be best, curious everyone's thoughts on that. I'd rather not make a separate SKU on the site just for the 78 year as it may end up confusing people.
 
LongDistanceRider said:
Make an adapter, no need for a different unit. The 1978/79 CB400T 1 & 2 use the bullets, '79 CM400T is a plug.
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OK, looks like they are both male so just need two female bullets that go to the 2-pin. Doesn't need to be very long either I suppose, like two or three inches should be good enough? I'll just put a 6mm PVC sleeving over it as well to make it nice looking.
 
I happy to report that we get full advance @5K rpm, maybe a bit earlier. I didn't have helper this afternoon so holding the throttle fixed at full advance and then grabbing the tachometer unit may have changed it a little. Spec is 4500-5350 so we're in the ballpark.
This is after my timing light quit and had to buy a new one and then the pickup adaptor plug was making bad connections, managed for wet 2 plugs in repeated kicking. Generally a pisser of an afternoon until everything worked as advertised.
So tomorrows plan after I really fix the adaptor is a good road test which should reveal everything is great.
 
LongDistanceRider said:
I happy to report that we get full advance @5K rpm, maybe a bit earlier. I didn't have helper this afternoon so holding the throttle fixed at full advance and then grabbing the tachometer unit may have changed it a little. Spec is 4500-5350 so we're in the ballpark.
This is after my timing light quit and had to buy a new one and then the pickup adaptor plug was making bad connections, managed for wet 2 plugs in repeated kicking. Generally a pisser of an afternoon until everything worked as advertised.
So tomorrows plan after I really fix the adaptor is a good road test which should reveal everything is great.
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What kind of timing light are you using? I just have one of those Innova 3551 inductive ones you can get at the auto parts store, but AZ has it too: https://www.amazon.com/INNOVA-3551-Inductive-Timing-Light/dp/B000EVYH72/. Works fine for this kind of stuff.

Good to hear it's still working well. When you spun it up in the earlier video I definitely knew it was working then! :lol:

As a small status update, I ordered enough parts to make 5 more. I have my buddy who did the cases to go over the CAD file to fix the mounting hole being off by 2mm so I don't need to file them on the next round of cases.
 
On a side-note, I realized I named this thread in a silly way. Can a mod rename it to "CB400T/CM400T/CM400E/CM400C/CB450SC CDI Reverse Engineering"?
 
LongDistanceRider said:
I bought this one https://www.oreillyauto.com/detail/...7d9c7148f/innova-timing-light/inn0/3568?pos=2 which has the tach built in but I haven't verified that it's correct. My tach unit is this https://gtc.ca/product/ta100-smartach-wireless-ignition-analyzer-and-tachometer/ which I know is dead accurate. Didn't pay attention to spark voltage reading.
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Ah OK. You have the same one as me, but with a bit more features. According to reviews the digital tach on those is apparently quite accurate. I ended up buying a couple 70s era portable inductive tachs cheap used on ebay and use those. My dad has a really nice expensive fluke that has the RPM inductive clamp for it and I verified those old tachs with the fluke and they're pretty close. Might be off by 20RPM or so, but good enough. As much as I like the old analog stuff, digital RPM is kind of the way to go. You can really dial things in tight with those kinds of tools, especially if they are accurate and calibrated.
 
Good road test done, 20 miles. I'll be mailing it back tomorrow.
Update on the Rex's unit. It's in a sealed plastic box, probably potted but maybe not. Ended up having to re-crimp all of the spade connections on it, 3 of them had the wires pull out so redid all of those.
 
LongDistanceRider said:
Good road test done, 20 miles. I'll be mailing it back tomorrow.
Update on the Rex's unit. It's in a sealed plastic box, probably potted but maybe not. Ended up having to re-crimp all of the spade connections on it, 3 of them had the wires pull out so redid all of those.
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Recrimp on the rexs unit or mine? I used fresh oem connectors with the right tool so I'd be surprised if it was mine.
 
Maraakate said:
Recrimp on the rexs unit or mine? I used fresh oem connectors with the right tool so I'd be surprised if it was mine.
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Your crimps are great. It's Rex's that were crap, fortunately they've held up till now but any one of them coming loose while riding would have been a nightmare to figure out on the side of the road. Who expects to have to check for loose wires in crimped connections by a company?
 
Unfortunately, the vast majority of motorcycle aftermarket parts leave a lot to be desired. It's now expected that you have "some assembly required".

With that said, I mentioned previously I ordered enough parts to make 5 CDIs for the manual bike, including the missing 1 MOhm resistors for your unit. They will be here tomorrow so I can put the AEC rated resistors in it and remove those blue generic ones, then pot it in one of the old cases and send it back out to you for your enjoyment. I took some time to repaint the used cases as well.
 
STATUS UPDATE 08-31-2022:

* Received CDI back from Jim. Replaced the 1M blue resistors with AEC-Q200 rated ones. Put the CDI in recycled case and potted it up.

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Kentonius said:
How soon until units available to ship?
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I have two cases left. I can build a few now, then it will be another 6-8 weeks to get another batch of cases. I've added it to the site so you can order it, but won't have pictures available yet.

You can order it here.
 
Maraakate said:
I have two cases left. I can build a few now, then it will be another 6-8 weeks to get another batch of cases. I've added it to the site so you can order it, but won't have pictures available yet.

You can order it here.
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Thanks! Just ordered it. It will be a good time for my 82 CM450e....
 
No, this is bolt it right up, route the harness, then plug and play. Just like the original. It's even potted in the proper type of electronics potting compound (and not the cheap $20 crap on amazon, the real stuff).

The only real difference between mine and an original OEM unit is the case is slightly taller to allow some additional room for the SCR transistors during potting, but it does not affect frame to gas tank clearance.

The reproduction case and potting compound is one of the reasons why the price is what it is, besides using automotive rated components. I think it's unacceptable that Rex's unit has a silly adapter and a plastic case that is zip tied to this adapter.
 
Maraakate said:
The reproduction case and potting compound is one of the reasons why the price is what it is, besides using automotive rated components. I think it's unacceptable that Rex's unit has a silly adapter and a plastic case that is zip tied to this adapter.
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Plus Rex's unit requires removal to do a valve adjustment.
RIMG0169.jpg
 
Kentonius, potting finished setting it up this afternoon. I actually have an 80 CM400E I'm working on for someone that it is in a running state so I put it on there quick to do a final verification and works fine. Will send it out tomorrow morning. Can't wait to see pictures and your success story with it!

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Maraakate said:
Kentonius, potting finished setting it up this afternoon. I actually have an 80 CM400E I'm working on for someone that it is in a running state so I put it on there quick to do a final verification and works fine. Will send it out tomorrow morning. Can't wait to see pictures and your success story with it!
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Wow… just wow. I’m pretty excited for it. I’ve got a bunch of work to do to it, new plugs, wires, plug caps, coil, new CDI!, etc. Thanks again for providing this service and product to all of us here. Just another reason to be thankful for such a community.
 
Kentonius said:
Wow… just wow. I’m pretty excited for it. I’ve got a bunch of work to do to it, new plugs, wires, plug caps, coil, new CDI!, etc. Thanks again for providing this service and product to all of us here. Just another reason to be thankful for such a community.
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Isn't this how it's supposed to be? Good people helping each other. No corporate crap here.
 
Arrived this morning here in sunny, dry Kansas! Looks great too... will take pictures when I get it out on the bike.
 
STATUS UPDATE 09-16-2022:

* Had my friend move that mounting hole over 2mm so I don't have to file them by hand on the next batch. Changed gauge from 14 to 12 so I can use that grommet without having to slather silicone around it on the outside to prevent the potting compound leakage. Expanded the width by 3mm to compensate for the increased gauge so the PCBs fit.
* Ordered 5 more of the improved design. 6-8 weeks as always. If this batch of 5 is perfect all around then will do 10 next round.
* Once the 5 are here and are good will just make a few already assembled and ready to go to avoid the 2 week lead time. Ordered enough parts to do at least 20 boards. Need to get with Matt to get some bulk pricing for the harnesses and connectors as that's the stuff I need more stock of.
 
Maraakate said:
Kentonius, potting finished setting it up this afternoon. I actually have an 80 CM400E I'm working on for someone that it is in a running state so I put it on there quick to do a final verification and works fine. Will send it out tomorrow morning. Can't wait to see pictures and your success story with it!
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Installed this yesterday, along with new coil, plugs, plug wires/caps, throttle cables, grips, etc. It is like a new bike the way it runs!! Thank you again!!!

Product review (albeit short) here: https://www.vintagehondatwins.com/f...tic-Parts-CDI-for-my-CM450e&p=78016#post78016
 
STATUS UPDATE 11-02-2022:

* New cases came in from metal manufacturer. Perfect fit. Don't need to modify anything! Will do another run of 5, then will order 10 for the next round.
 
Hey guys, hope everyone had a good holiday! Bikes have taken a back seat for me, except on days where it's at least 50F out. :)

I still have 3 cases left for this round. With spring looming around the corner now is a good time to get the parts you need and not be left hanging come April.
 
Down to my last case of CDIs for the CM400A and CM400T. Ordered 10 cases from the metal manufacturer this week, but if you're like me and started riding on these nicer days then you might want to jump on this before the lead time increase to another 6-8 weeks as I wait for cases.

As always, you can buy the CDIs at my site https://cm400a.nightgrease.net/ or from my ebay site at https://www.ebay.com/usr/eggmatorch.
 
Metal cases done from manufacturer, full-filled two back orders and now 8 cases are available as of 04-21-23.

I'm also working on an adapter plate for the Dynatek Mini 0.5ohm coil. It can mount as-is. If anyone out there is interested in having me make an adapter for the coil harness and proper coil wires cut to length and soldered then contact me. I haven't come up with a price for that, but I'd imagine about somewhere between $20 to $30 depending on cost of materials.

PS: Can someone rename this thread to "Brand New CDI available for CB400T/CM400T/CM400E/CM400C/CV450SC"?
 
Status Update 06-08-2023:

This past month has been my busiest so far with the CDIs for both models. I'm down to 3 cases already. I contacted the metal manufacturer early this time around as I would like to get some at the trade shows my buddy is going to next month. Used a lot of money the for these sales on reinvesting to expand the stock. Especially in regards to components. I've been trying to stay on top of that as much as possible due to the component shortage that has been on-going since COVID.
 
Maraakate said:
PS: Can someone rename this thread to "Brand New CDI available for CB400T/CM400T/CM400E/CM400C/CV450SC"?
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Done. I just saw this now. FYI, if you added that last sentence later by editing, just know that it doesn't register as a "new" post so I may have already looked at the post previously and didn't realize you added that until now. Or I just missed it. :rolleyes:
 
I locally found a seized CB400T engine for $50. Stator, etc. is on it. I'll be picking it up Friday and getting the top end, etc. off it so I can have the bottom end to spin it with a drill so I can bench test the manual CDIs without having to own one of the bikes. Analog meter test works fine, but I'd like to be able to test it actually sparking before I send them out.
 
Maraakate said:
I locally found a seized CB400T engine for $50. Stator, etc. is on it. I'll be picking it up Friday and getting the top end, etc. off it so I can have the bottom end to spin it with a drill so I can bench test the manual CDIs without having to own one of the bikes. Analog meter test works fine, but I'd like to be able to test it actually sparking before I send them out.
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You're accumulating all the equipment for a full diag and post-production testing facility. Since the engine is a spare, you should pull the lower case and remove the rods so you can mount the bottom end to a platform and freely spin the crankshaft with a motor of some sort.
 
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