Full Throttle Problems CN250

Posts: 1163

Check the 2 wires at the coil connection. In addition to making sure the connections are tight check where the wire joins the terminal. I was having similar troubles and found one of the wires was broken. Only 2 or three strands of copper left. Also check where the wires go into the cdi. Push and pull each wire to see if one or more are loose inside the connector. I had that problem also last year. I had to take the wires out of the connector (female end) and crimp them, then put them back. Last but not least make sure the ground connections are clean, tight, and the wires are intact.

Posts: 10

OK, thank you I will check again. I have the seats back out so it will be easy to go over all of it again. I will keep checking. If yours (im4seven) acted the very same way with wires then surley that must also be my problem. I just don't see anything loose right now but will make sure.

Should my gas filter be running fuller? Mine seems to be about 1/2 to 3/4 full. Are there different size vaccum check valves on the bottom of the gas tank? What are the thoughts of doing away with the vaccum check valve and just putting in a manuel shut off? I suppose it could fill the crankcase with gas if you forget to shut it off over a period of time. Any other draw backs? Thank you everyone!

Posts: 10

I GOT IT STARTED AGAIN! Here is what has been happening. I took the vaccum line off the gas tank and put another hose on that I could add suction to. I sucked on it and got the gas filter full. It still would not start so that eliminates the check valve being a problem.

I pulled every connection apart and checked every wire at the connections. I added electrical contact grease on each one while they were apart to help in making good contact. It still would not start.

I unscrewed the plug wire and put it back together with contact grease. I looked at the plug, it was a little wet. It still would not start.

I put my hand over the intake of the carbarator while turning it over. It's not the choke and it's getting gas but it still would not start.

I was walking away to come ask you guys what componet could be bad and how to check it. I went back and tried it one more time, IT STARTED! Laughing

The seats are still out of it and I am going to install some top secret performance parts coming from BIGIE. After that I then will see if the top end works as it should. Twisted Evil

Thank you im4seven for keeping me going in right direction, thank you everbody. More to follow..............

Posts: 896

Posts: 1 · Joined: 12 Nov 2007 Posts: 1 Pictures: 0

I too, had the exact same problem. Went as far as taking carb apart. Finally pulled out th CDI unit, found an indentation in the end of it from a electric box mounting bolt. At low speed, not enuf vibration, it ran ok. At higher speeds, vibration would cause CDI to short out across the mounting bolt. I went ahead and got a new CDI unit from Roketa, and it solved the problem.
Hope this helps.Rick. Let me know. you can email rchristie@c3bb.com

Posts: 10

Well still can't find the problem. I changed the CDI and it didn't fix the problem. The only way I can get it started when it's cold is to take off the air filter and put my hand over the carb. intake. Does that point to any problem? I have not ruled out a wire problem because the battery is dead after setting for a couple days. After you get it started and warmed up it will restart just fine and idles great. There is a dead spot just above idle that you have to pump the gas and baby it to get past. Then it runs fine until at full throttle for a short time. Then it quits but will restart. Does anyone have more suggestions in what to look for? I have checked the wires and connections over several times. I must be missing something.

Thank you everyone for the help!

Posts: 4307

the starting problem sounds like the choke not working when its cold

the bog at part throttle sounds like the pilot jet is clogged or to small

the top end miss and cut off sounds like the wires in the connector of the cdi plug are coming loose and not making good contact. mine did that, I took them out of the connector and crimped them and put them on the terminal of the cdi.

also put the cdi in some styrofaom to keep it from moving.

ps. the 110 parts are ordered

Posts: 1 · Joined: 27 Sep 2008 Posts: 1 Pictures: 0

Most of the cn250 engines and the gy6 150 engines have a automatic choke on the carb, for some reason once they get a little dirt in them they get stuck in the choke position and it won't let you get to full throttle. THE FIX !!! remove the carb a take out the electric choke, fill in the hole were the choke was with J B WELD... you will have a little hard time starting it in the winter but once you do this the kart will run a hundred times better. I did this to a carter fx 150 and my new hammerhead ss250. ever since they both run great.

Posts: 10

Well after crawling all over this this I now have improved from a sustained speed of about 20 - 25 MPH to about 35 - 40 MPH.

I have changed the air filter, spark plug, CDI, tried diffrent jets and checked all the electrical connections. Bigger jets helped. The biggest improvement seemed to come from taking the vaccum controlled gas valve off at the bottome of the gas tank and putting on a manuel shut off along with a 1/4 gas line to the carberator.

After 40 MPH for about about 30 seconds it will still start cutting out and then will die if you don't back out of it slightly. If you back clear out it will also die. After the engine does quit in about 15 - 20 seconds it will restart. It still seems to me like it can't get enough gas. Has anyone else experienced this problem?

Also apparently the choke isn't working. Can I put a manuel choke on this or how do I check this one out?

BGIE can you send me a new choke with me new fenders?

It must be running pretty good, I tipped it over for the first time and broke two fenders. The roll cage really is fantastic on these things, not a scratch on me.

Posts: 260