Full Throttle Problems CN250

Posts: 10

Hello my friends,

I have a problem with my new CN250 that I hope someone has the answer to. I have not made any modifications or changes to this engine, it's all brand new. And as most of you have experienced there is no way the company I bought it from is even going to respond that they even sell the things. Well only when you place an order will they to talk to you. It's really very funny how they can ignore you after purchase. That's a whole diffrent story.

Here is my problem, my buggy runs just fine in the lower speeds and at idle. It's when I get up to about the last 80% of the power band. If I go full throttle at this upper end for 20 to 30 seconds it will sputter and start to die. If you don't back out of it then it will die but will restart again.

I found a hose clamp that is on the engine side of the carburator stripped and was loose. I replaced that but it still has the same problem. I tried it with out the in line fuel filter, same problem. I eliminated the possibilites of it being a fuel cap vent problem. Even though it's new I checked the air filter and it's OK.

What should I try next? Can it be the vaccum to open the check valve on the bottom of the gas tank or the check valve it's self? Is there a chance of it being carb. or valve settings? I would think it to be something rather simple since this is new. I have no clue what to try next. I hate to spend money replacing parts that need not be replaced. Can I eliminate the vaccum check valve on the bottom of the gas tank and just put in a manuel shut off? Would this be a place to start?

Please offer any help or opinions that have. Thank you for your help - Kacee.

Posts: 4286

welcome to buggynews, I would check the wires going to the coil, the wires going into the cdi, the tads that hold the wires in the connector can be loose and the wire will push out slightly and not make a good connection.

what buggy do you have?

Posts: 1215

have you checked the coil wires to make sure they are tight making good connection and also the wires plugging into the cdi
and make sure the small connecters hasn't pushed back out of plug.
what about the petcock have you checked it to make to sure nothing has gotten inside of it restricting gas flow,when your gas filter was on it was it staying full of gas.
vacuum lines for splits or leaks
yes alot of guys change to a manual gas shut off and go with bigger gas line to keep plenty of gas going to carb.
also has this done this from the get go and have you ran it long enough to get a plug reading to see how it is running.
who did you get your buggy from?
pud

Posts: 1215

Posts: 10

Thank you for the suggestions with my problem. Here is what I have found:

The spark plug wire was loose, wow, I could not believe it! However that was not the problem. Same results after a test run. Then I pulled the spark plug. It is bone white on the end. That means it's running really lean right?

I pulled the check valve in the bottom of the tank. Everything seems OK there, just to make sure I poked some small holes in the upper end of the screen to lower the restriction (Sorry to the engineers who came up with this design). I checked the wires that was easy to get to and found nothing a miss. I was really surprised that two people (Who no doubt are knowledgeable from past postings and coming to the same conclusion) came up with a wiring problem. You guys are good! However my machine still has more problems.

Both what I consider to be experts asked what type of machine. It is a Kinroad Xintian from GoKartsUSA, GK250.

Same results, it runs great until a full throttle run of 30 seconds or so in the upper power band and it flat cuts out. If you don't back out with still a little gas pedal into it the engine will completely die and you will have to restart. Lower end to mid range it's great. Even mid to upper RPM it's OK but after about 20 - 30 seconds it falls dead.

Thank you all for your help but I am still needing more. Am I on the right track?

Posts: 4286

if all the electrical connections are good. and the spark plug is that white then its running way to lean. the 250 buggy's come with the same size main jet as a 150 to pass emissions.

I would change the main jet to a 122 or 125, those will be fine with the stock air box

Posts: 1163

While you are in there changing the jet make sure you check the float level.

Posts: 10

Thank you guys for helping me, greatly appreciated. Eric I will be calling you for some parts. I have checked the wiring and sure can not find anything else loose. And of course I want more power any way so the jets and air filter change is a good idea. Do you have some more suggestions for power while we are at it?

That is a great idea from im4seven about the float level setting. I didn't even think of that one. That very well could be the problem. I sure will check that when changing out the jets, thank you.

As they say "To be continued".
Thanks everyone - Kacee. Wink

Posts: 10

Well there must be an electrical connection problem also as you guys thought in the beginning. The thing will not start, will not even fire now. I will keep looking............ Rolling Eyes

Posts: 10

OK, I checked all the wires, everything looks good and tight. I pulled the plug and turned it over, it's getting spark. I tried it and it started, it died on warm up and now will not start again. The gas filter is half full. It should be full shouldn't it? Should I try taking out the vaccum check valve on the tank and go with a manuel valve? Sad