Jonway YY350-9A CDI?

[slacker220]

Hello :)! You all seem very nice, and helpful so I created an account in search of help for my poor little China motorcycle. I have a Vitacci 250cc GTO (Jonway YY350-9A). It has a weird issue recently where one cylinder is not firing unless at high RPM. I have changed the plugs in hopes that was the issue. Then my dad asked me to swap the spark cables around to see if the issue persists. The same cylinder was not firing unless at high RPM. So he had me unplug the spark cable on the right side (if sitting on it), and the bike died. Put it back on, started bike again, tried the same thing on the left side, and the bike remained running. My dad suggested buying a replacement ECU, and CDI. I found the ECU, and ordered it. I can find the CDI online, but not sure which one to buy. Also not sure where it goes on the bike. From the images I saw I can't find the part on my bike. Would anyone have one of these bikes or a version of it, and would be willing to either tell me where the CDI goes or send me a picture of where it goes? I would be extremely grateful!

:thanks:

[JerryHawk250]

Welcome aboard! Make sure you are using the right spark plugs. I've heard from a few others with the same bike coming with the incorrect plug.

[slacker220]

Thank you so much for responding! My dad suggested that as well. So I put in some new NGK CR8E plugs. Found them through some Google searching, and they were recommended. However I still have that issue

[JerryHawk250]

That is correct. It takes a NGK (1275) CR8E Standard Spark Plug.

[Falkon45]

if it's fuel injected, it shouldn't need a CDI. If it's the same cylinder, you more than likely have an internal problem. Try adjusting your valves. If that doesn't work, and you have access to a borescope, look inside the cylinder to check for problems. It's seems like you may have lost compression in one cylinder.

[slacker220]

OK, thank you for confirming the correct spark plug. Also thank you for the info about the CDI, and that explains why I couldn't find anything like the boxes online mounted anywhere on the bike :) . The rest of that is way over my head so I guess it now waits until my dad has time or I need to find a place around Fort Worth, TX that is willing to work on it.

[slacker220]

Venom motorsports emailed me. Found the problem. One of the coil packs was wired wrong from the factory. It finally just burned out causing my recent issue. It also explains this weird electrical issue I was having :). Got a new one on the way! Thank you all for the pointers. Will update when arrives, and installed. If anyone is interested I can post pictures of the bike, and the few mods I have done / plan to do!

[Daslayer]

It might actually be the crank position sensor. I had a similar problem where one cylinder would not fire and occasionally not want to start but once running and driving it was somewhat fine. I check that the ignition signal wasn’t triggering on one output from the ecu and initially thought it was a bad ecu but the ecu can only fire if it knows where the crank is in it’s rotation and it was getting occasional bad signal. Swapped out the sensor and now it’s perfect. Before you spend any money on a problem be sure that is the problem or you will spend a lot of money replacing perfectly working components.