YS cdi voltage
 

I ran into a problem getting a new motor to start, prob because I ended up flooding it. Anyways while looking for problems I cked the voltage output of the cdi unit and it was at 4.4V. I have 5.35V regulated going into it. I tried a 2nd cdi unit and it was at 4.95V going to the motor.

Do these voltages seem ok? I never cked them before and was wondering why there's such a difference.

RE: YS cdi voltage
 

I have been using 5.5 and 5.9V since day one, and it can take it no problems.

RE: YS cdi voltage
 

The voltage output of the cdi should be a spike of thousands of volts.

However, assuming you meant the voltage into the cdi unit, then if you measure the voltage at the regulator and it drops after you connect the cdi unit, then you have a cdi that's faulty (drawing a huge current continuously) or a reg that's faulty (can't supply much current). When the cdi is doing nothing it should draw very little current.

An oil fouled or flooded spark plug won't clear itself as easily as a glow plug will. About 3 times over 3 years I've had to pull a plug to clear it.

If all else fails, power up the cdi with a 4 cell pack, put a plug in the cap and turn the motor over and watch for the spark. You won't have to ground the plug to the motor like a lawnmover as the braid is the ground return..

Cheers

RE: YS cdi voltage
 

Is the output you refer to, the lead going to the back of the engine? I have never checked this as I never thought of there being voltage there. This is the lead that goes to the sensor that triggers the capacitor to discharge. I suppose there would have to be some current there for this to work. If so, the voltage may not be the same as the input. I don't know much about this so maybe someone who does can confirm if this is the case or not. This is just how I think it would work.

RE: YS cdi voltage
 

I was refering to the lead that goes to the sensor. I just assumed that this would be the same voltage that's applied to the plug?

Motor started first pop the next day. I also found a split in the fuel line running from the ck valve to the carb which wasn't helping matters. I'll have to switch back to the other cdi and see how it runs.

RE: YS cdi voltage
 

No. The plug gets very high voltage sent through the high tension lead from the capacitor.
With the engine running, wriggle the lead that goes into the back plate. If the engine misses then the sensor lead wire is broken. The vibration causes it to break at the point where the wire is hard soldered to the back plate. I have had this problem with my 170 and 175cdi's. I made a small bracket to support this wire and so far i haven't had this problem again.

RE: YS cdi voltage
 

Thks for the info and tip. I'll do that also.