After pulling off the remote/alarm system, from my 90 cc sunl 4 wheeler, I have been through 4 cdi's in a week. The cdi's go out after decelerating from a high rpm to idle. I am curious on whether or not there is a shunt or should be a shunt on this bike.

If anybody has any idea about why this would be happening, please advise me so I can quit buying cdi's.

Thanks
Joe Armagh

 

WHAT?
No one even has a clue? Could it the regulator?

 

PM Lynnedwards. He knows electrical. My suggestion is to put back on the alarm. My kids have a 90 also, the alarm is on there but we do not use it.

 

Thank You. I just sent him a message. I do not want to go back with the alarm/remote if I can keep from it.
There is excess electricity getting to the CDI some how, I just have to find out how it is getting there. Maybe I just got some bad CDIs.. But if anyone knows it will be Lynn.. I hope.

Thanks Again

 

Well, I put the new different color CDI on it and have tried to get it to POP and it hasn't done it. I still have a new regulator for it just sitting, but so far the CDI has worked perfectly. As of now, I can only guess that the CDIs with the green color connectors are better than the ones with the brown color connectors. OR the brown color connector is NOT the correct one for this bike. Maybe I just bought a bunch that were bad .

 

The standard 5 pin CDIs are powered with high voltage AC off the stator, not DC from the battery. The high voltage AC going to the CDI at idle is 45 to 80 volts AC and is roughly proportional to engine speed. At high engine RPM it can be several hundred volts. CDIs should be built to take this.

I suspect you had a bad batch of CDIs, especially if you got them all from the same place. They probably made a batch of CDIs with the wrong part loaded causing it to fail early in its life. This could be things like putting in a 250 volt capacitor where a 500 volt capacitor is required. Or putting a 10K resistor in where a 1K is needed - causing a transistor to turn on and off too slowly and overheating at high RPMs. Or putting a tantulum capacitor in backwards, etc.

I'd go with the green one and see if it lasts. I suspect it will.

Shunts [from your PM] are used to even out current loads on AC powered lighting systems. This is unrelated to your problem.

The alarm can be disconnected with no problems, other than you can no longer use the ignition switch to shut off the quad (use the handlebar kill instead). Alarms tend to drain the battery if the quad sits around without a maintenace charger attached so if you don't use it I'd just unplug it.

 

Thank You so much for answering, and so far you are exactly correct. I did disconnect the alarm/remote and reconnected 2 wires and BOTH the key switch and the handlebar switch works.

 

This is a follow up.
It is still running and without any problems.. I guess it was just a batch of BAD CDIs.

This little 4 wheeler is very, very fast.

 

Thanks for the follow up.

Often threads die without any final resolution, and others searching for help for their own similar problems are just left hanging. They wonder if the original problem got fixed, or did the poster just get fed up and quit? It is nice when the final verdict comes back.

Glad your quad is still running!

 

Last follow up ... The little bike has not missed a beat. Has the same CDI and the same regulator, and has been rode hard.

It must have been just a BAD batch of CDIs. I guess that happens.

I 'm happy.

THANKS Lynn Edwards and THANKS Lockman0075