Reliable CDI?

[Piston_Pedals]

I have about 250 miles on my bike so far and have much of the bugs worked out. Most of the time it runs pretty good. But my experience with the stock CDI's for these HT motors has been dismal at best. The one that came with my kit.. Bad out of the box. Replacement worked for 7 miles before the stock plug cap broke. Put a whole new wire on it rather than replace the cap and it ran good for many miles then died. Replaced the CDI a third time and bought a couple spares at the same time.. Got 100 miles out of one, then it died on a long ride.. Replaced it with one of the spares I put in my bag which was new but turns out it was defective.. Had to pedal to where I could get cell signal and call for a ride... When I returned home... I popped the other spare CDI on and bam back to life. I did check them to make sure the plug wire was tight on the screw of the CDI and the rest of the wiring was ok etc...

When I put my meter on the magneto, it always puts out voltage, ground is good, resistance is where it should be... But I just keep eating CDI's or they are bad out of the box. I've ordered them all from Amazon, different vendors... Each one the box is the same but the wire is different. I've been replacing the wires with 8mm single wires I bought at the Autozone that have good crimped ends.

I often ride this bike 10-20 miles at a time, longest has been 38 miles.. I gotta be honest my bike will run a smooth 35 mph with 26" tires and a 44 tooth on level ground. So I don't really need more performance (but I don't want to loose any).. It's plenty fast enough and cruises great at 20-25mph. I just need reliability... What is the most reliable CDI out there for the HT engines that isn't super expensive? Is the BBR stage 1 reliable? I've heard of someone using the CDI and coil from a Yamaha PW80.. I'd love to ride 100 miles over the span of a day on an HT motor and not have the ignition melt down.. Is it possible?

 

[Wrench]

Does your spark plug boot have a resistor built in? If not I suggest using a resistor type spark plug.
Resistor plugs reduce electromagnetic interference with on board electronics. (CDI)

CDI needs a resistor before the CDI either it be in the spark plug boot or a resistor plug. But don't use both.

The CDI comes with a resistor built in the plastic spark plug boot. But If ya changed the Spark plug boot to a rubber type boot you will need to use a resistor type spark plug or your CDI will FRY

 

[mark20]

ive personally only have had 1 cdi crap out on me, and thats cause i left my bike out during a snow storm.

sounds like something is going on somewhere else, what type of sparkplug are you running? as that could screw up the cdi's.

but, if your 100% sure. give this cdi a try. as it uses a real deal motorcycle ignition
https://www.ebay.com/itm/High-Perfo...534357?hash=item3d15f74f95:g:4d4AAOSwAWNcuhTD

 

[Piston_Pedals]

The CDI comes with a resistor built in the plastic spark plug boot. But If ya changed the Spark plug boot to a rubber type boot you will need to use a resistor type spark plug or your CDI will FRY

I am using a resistor wire with a B7HS, or atleast I was told the wire was when I bought it as I asked specifically.

This is what I was sold..

https://www.autozone.com/ignition/p...gle-spark-plug-wire/132036_0_0&searchText=32m

 

[Piston_Pedals]

ive personally only have had 1 cdi crap out on me, and thats cause i left my bike out during a snow storm.

sounds like something is going on somewhere else, what type of sparkplug are you running? as that could screw up the cdi's.

but, if your 100% sure. give this cdi a try. as it uses a real deal motorcycle ignition
https://www.ebay.com/itm/High-Perfo...534357?hash=item3d15f74f95:g:4d4AAOSwAWNcuhTD

Well I am pretty sure, assuming the wire I have been using is ok.. Maybe that's what is up with it.. I've broken two of the chinese plug caps and couldn't get an NGK cap locally so I decided to replace the wire instead to get rolling again quickly. Considering I've had two of the CDI's that were doa, I also thought maybe there is a possibility there was bad batch of them since I've bought them all recently, 3 of them were the same mfg. The last one went over 100 miles with this wire before it died..

The description says RFI protection, but doesn't say resistor specifically. If I set my meter to 20K ohms and measure the wire, I get 13.5...

 

[Piston_Pedals]

Something else, is heat an issue with them? I notice that some aftermarket motorcycle cdi's have aluminum heatsinks compared to our epoxy dipped and trapped in a plastic box with no airflow style of cdi units.. I've often been riding in 90-100deg temps for long distances.

 

[Chainlube]

I've never had a CDI issue, I have had a few mag issues. Before you go through any more CDIs you should check your magneto, take it out and sand the back off it with fine sandpaper and the same with the mounting surface of the case. Then put it all back together and see if that helps, no money spent just a little labor.

 

[Piston_Pedals]

I've never had a CDI issue, I have had a few mag issues. Before you go through any more CDIs you should check your magneto, take it out and sand the back off it with fine sandpaper and the same with the mounting surface of the case. Then put it all back together and see if that helps, no money spent just a little labor.

I did that when I built it, but I'll pull it and check it. I get good continuity between the engine block and the spade connector for the black wire where the CDI connects though. When these problems first started happening, The original coil was putting out voltage and the resistance was on the money, but I replaced it anyway. (The replacement was one of the heavy duty ones with a 12v accessory wire, but I am not using it and it is capped off.) The replacement coil put out the same voltages as the original and the bike still wouldn't run until I swapped the CDI when I originally built it. Since then I've gone through another couple CDI units and then had a couple bad ones out of the box.

The place I bought my motor which was a direct front for a manufacturer (fastbikemotors.com) told me that demand is so high they were sourcing motors and parts from where ever they could and that the QC has gone down quite a bit because the factories are cranking stuff out too fast. If you see my initial post when I joined and started building my bike about a month ago.. You'll see that the bridge in my exhaust port was snapped out from the factory and I ended up having to machine out the remnants.. lol.

Everything points to CDI problems, but I think it's strange especially when you more experienced folks say you have no issues with yours CDI units blowing up.

 

[YetiWoodz]

Dose your spark plug boot have a resistor built in? If not I suggest using a resistor type spark plug.
Resistor plugs reduce electromagnetic interference with on board electronics. (CDI)

CDI needs a resistor before the CDI either it be in the spark plug boot or a resistor plug. But don't use both.

I have a resistor cap and resistor spark plug in. What bad happens if you have both in at the same time which I do? I only did a few rides with that setup. Could that be why my engine takes forever to start and sometimes shuts off?

 

[Wrench]

I am using a resistor wire with a B7HS, or atleast I was told the wire was when I bought it as I asked specifically.

This is what I was sold..

https://www.autozone.com/ignition/p...gle-spark-plug-wire/132036_0_0&searchText=32m

That spark wire and boot ain't got no resistor in it. That's why ya keep burning out CDIs every 100 miles or sooner.
Your gonna have to use a Spark Plug Boot with a Resistor built in or use a Resistor type spark plug.
But don't use both or you will have a weak spark due to too much resistance