ChinaRiders Forums - View Single Post - Bought a new CDI box....How can I confirm if it's AC or DC?

Thumper · 03-04-2023, 08:09 PM

You already mentioned good compression a while back. I have a hard time believing that the spark you had BEFORE installing the new CDI unit was any problem, and I also don't thing the timing is different for a GY versus Zongshen 229cc engine. This is based on experience...I installed a GY 50, 100, 125cc variable CDI unit on my Templar, and it is fine.

You know what they say... if you have compression, spark and fueling are the all you need.

Have you checked the valve clearances? Otherwise, I say carb.
That is a pushrod engine, so
Intake should have at least 0.002" (0.002"-0.004"), and exhaust at least 0.003" (0.003"-0.006").
It should at least start if gaps are 0.001". They just expand when the engine heats up and may not close all the way. You can see the Timing mark in the small port on top of the stator housing (T for TDC).

FYI, here is the description for the adjustable AC CDI unit I got for my ZongShen 172FMM-3A (249cc):

"Naraku Racing AC CDI with adjustable timing for customized tuning on 50 to 150cc GY6 engine based vehicles. The timing adjustment screw is set in the middle from the factory and has approximately 12 to 13 turns in either direction to advance or retard the timing. The screw clicks into place at each setting. Please note: This is only compatible with AC charging systems. Please confirm plug connection is correct for your vehicle. Please see our Warranty & Returns Policy."

I see no issue with compatibility for AC based CDI between GY6 and ZS engines. Obviously, you have spark. Timing isn't an issue.

03-04-2023, 08:09 PM	#7
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,380	You already mentioned good compression a while back. I have a hard time believing that the spark you had BEFORE installing the new CDI unit was any problem, and I also don't thing the timing is different for a GY versus Zongshen 229cc engine. This is based on experience...I installed a GY 50, 100, 125cc variable CDI unit on my Templar, and it is fine. You know what they say... if you have compression, spark and fueling are the all you need. Have you checked the valve clearances? Otherwise, I say carb. That is a pushrod engine, so Intake should have at least 0.002" (0.002"-0.004"), and exhaust at least 0.003" (0.003"-0.006"). It should at least start if gaps are 0.001". They just expand when the engine heats up and may not close all the way. You can see the Timing mark in the small port on top of the stator housing (T for TDC). FYI, here is the description for the adjustable AC CDI unit I got for my ZongShen 172FMM-3A (249cc): "Naraku Racing AC CDI with adjustable timing for customized tuning on 50 to 150cc GY6 engine based vehicles. The timing adjustment screw is set in the middle from the factory and has approximately 12 to 13 turns in either direction to advance or retard the timing. The screw clicks into place at each setting. Please note: This is only compatible with AC charging systems. Please confirm plug connection is correct for your vehicle. Please see our Warranty & Returns Policy." I see no issue with compatibility for AC based CDI between GY6 and ZS engines. Obviously, you have spark. Timing isn't an issue. __________________ -2022 5 speed Templar X Orange, OEM 51T rear sprocket, 14T front sprocket -NOS 2020 KTM 250SX (2-stroke motocross), less than 10 hours on it Last edited by Thumper; 03-05-2023 at 07:24 AM.
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