2nd bad magnedo and cdi in a week

[happycheapskate]

Sounds like a quality control issue. If anyone finds a good heavy duty replacement part, they should post here. Then other users of that engine can just go ahead and buy the improved part ASAP and keep the original for a spare.

 

[joey d]

took another long ride today and the magneto went again!

wired blue to blue
black to black
white capped off
no kill switch

I have only gone on one successful long ride with my friend. I have done ok for many short rides. but when I try to ride all day I burn up a magneto. I have tried ordering from different suppliers. with no luck. never had this problem with any other motorized bike I have ever built. don,t know why it is happening. all connections have been soldered. and shrink rapped side cover has been sealed with silicone. just cant make this one reliable.

 

[RdKryton]

There was a thread a while back where it turned out to be the CDI was too close to the exhaust and after a while of hard running the CDI would just burn up. He moved the CDI mounting location and the problem went away.

Jim

 

[joey d]

my cdi is working fine and I have tried swapping it out. It is a decent distance from the exhaust and my exhaust is heat wrapped. I have felt it after a good ride, it doesn't get warm. thanks for the response. I appreciate any input because I am out of guesses. I am now at the point where I bring an extra magneto every time I go riding. but this is getting expensive and just plane stupid.

 

[Al.Fisherman]

Just have to throw this out there...Are you sure that you are installing the magneto correctly? When wired correctly the blue wire will come off of the top post, the white off the bottom post and the ground goes under one of the magneto mount machine screws. Also the wafer insulator is smaller on the engine side. The larger side to the magneto cover. It will work with the black wire attached to other places but better on the magneto itself.

 

[Dilly Bar Rob]

Hmmm, I can maybe think of one more thing.... Have you checked your spark plug? Do you use the chinese plug or a replacement?

I wonder if an intermittently shorting spark plug could kill a magneto/cdi...

The reason why I ask is because I recently had some driveability problems (engine seemed to "miss/sputter" sometimes, then run just fine again) and I thought it was a dirty carb. Cleaned the carb, didn't help. I doubted it could be the plug as it was almost new and when I checked it's color the day before it looked fine. I checked it again, inspected closely..... low and behold, the electrode was loose! You would shake the plug and see the electrode jiggling around, almost making contact with the ground electrode at times!!! Changed the plug for a bosch from my other bike and the problem was gone.

I have no doubt that if the plug would be to short out completely at a high RPM then that would be hard on the magneto/cdi....

 

[joey d]

The magneto is installed as it should be. I am running the stock plug and plug boot. Ill have to swap them out and wait and see. thanks

 

[happycheapskate]

If it fails again, buy another brand CDI and start from scratch. Check your ground connections as well esp if you're running lights. Good luck.

 

[cabinfever1977]

After reading everything i would have to say its installer error.
You tryed ordering from diffrent companys and still have the same problem.
I would say it was from you hooking the kill switch to the blue wire but you unhooked the kill switch, so i would say you still hooked something up wrong.

Have someone else hook it up and install it for you or go get a manual with pictures.
The stock plug and boot usually work fine, but it couldnt hurt to replace them.

 

[danlandberg]

I agree Au Steve, The normally closed switch (like a refrigerator door switched). Closed when out and open when pushed in. is the safest way to stop the mag signal to the CDI. (I would do this on the blue wire (+) But I put the kill switch wires into the CDI wires with no mag or CDI failure! Always use the kill switch at idle, especially if you are using the white to ground! Don't do this going down hill at 40mph +, and have lost your brake! (But it is better to fry a mag and or CDI, than to crash at that speed!).