350x not running right

[Awsmjoey]

I've read some other posts of people having similar problems to what I'm having but none of them hit the nail right on the head. I got a 350x that I recently picked up on a steal of a deal for $340 running and riding. The thing is while it runs it doesn't run right. You start it up and it runs for 5-10 minutes. It runs strong but then it will just start to bog down and it starts back firing through the exhaust. I have replaced the soark plug and last night I cleaned the carburator. I rode it last night after cleaning the carb and it did run alot better but still did the same thing it always does. I was doing some donuts in the snow and looked down and my exhaust pipe was glowing red so I shut it down. Usually when it dies it always starts back up again in just a few kicks. Last night I let it sit and cool off though. Some told me that the jets in the carb are bad and if that is true do I need a new carb or can I get it rejetted. I have heard of rejetting before but do't know much about it, how much it costs, or where to go. Any info on that would be appreciated and also if anybody has any other opinions on what the problem could be that would also be greatly appreciated.

[hatc200x1]

Pull the plug, and tell us what color is the end of it? If its a lighter or if its white, its running way to lean. If its a really dark color, then its running a bit rich.
To me it sounds like its running really lean. Your exhaust should not be glowing red....
Let us know and we can go from there.

[Awsmjoey]

Okay, I'll go check that out here soon and let you know what I find.

[Awsmjoey]

Just checked and the center of the grounding electrode was a lighter grey but then around the rim it was black. I also forgot to mention that when I do run it it will usually only run with the choke on.

[hatc200x1]

Thats to lean, it should be a nice dark tan. Pull the carb back apart and take a look at the jets. There should be a number on them, the main jet stock is a 138, and the pilot is a 40-42 stock. Also while your at it make sure your air filter is clamped on correctly, along with all the carb boots, and intake boots. So pull the carb apart and let us know the jet sizes and we will go from there.

[Awsmjoey]

Your saying the number says what the sizes should be right? How do I check what the sizes actually are?

[hatc200x1]

Do you have any aftermarket parts on it? Such as exhaust/ intake mods? Also it will be running leaner in colder temps due to the air being denser.

There should be a tiny number on the jets that says what size the jet is.

[Awsmjoey]

I don't have any aftermarket parts on it. I got it from a friend of mine and he had the motor rebuild but I'm pretty sure the fuel system was left stock. I know the exhaust is stock.

[hatc200x1]

Ok, he may have put in a hi compression piston or aftermarket cam when he rebuilt it... Report back when you check what jet sizes are in your carb.

[Awsmjoey]

Okay, will do.

[Awsmjoey]

Well I may have posted too soon. Just went out a little while ago to mess with it. I figured I'd start it up and spray some starting fluid on the intake boot to see if it was leaking. That was all fine. I let it sir and idle for a few minutes and to my surprise it didn't die. I turned the choke off and adjusted the idle a little and still kept running fine. Then I aired up my back left tire and took it for a ride. Probly rode about 45 minutes with no problems until the tire went flat again. Not sure what fixxed it. Maybe sitting over night did something for it. Now I just gotta get some tires and I can start working on cosmetic stuff (as long as it doesn't start giving me more mechanical problems agai). Thanks for the help though. While I may not have had to use the information today I still learned something and might use it another day.