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General Dirt Bike Questions

Cascadia

Cascadia

Undecided
Location
Orem, Utah
It seems like I have a lot of question since I'm newish to dirt biking and bike issues. And it seems lik a lot of other guys are too. I don't like starting new threads every time I have a new question and can't figure out where to put it. So I thought having a general all around question thread might work out.
 
Cascadia

Cascadia

Undecided
Location
Orem, Utah
My first question is with my new ktm. It's a 250 xcf. Ran great when I bought it. Then the weather got cold. It would bog down when I hit the gas. Almost to the point of cutting out. I was thinking it was the weather but its warm now and it's stored in a warm garage. But it's still doing the same thing. What needs to be adjusted and how? It idles great on choke and without choke. But as soon as you hit the gas it wants to die. Help?!
 
anderson750

anderson750

I'm working on it Rose
Location
Price, Utah
Sounds like you have a clogged circuit in your carb. Take it apart and soak all the jets in ammonia for 15 minutes and rinse thoroughly with water and blow out with air and Allow to dry.
 
jentzschman

jentzschman

Well-Known Member
Location
Sandy, Utah
As I understand, it could be either your pilot and or air screw. I would also check the jets to make sure they are clean. If jets are clean then it needs a re jet. Check float levels first as I have been told that is very important. If that is in spec then start with the pilot jet and or check needle clip position. If I'm not mistaken, setting the air screw in conjunction with proper pilot jet will handle all the low end throttle positions. The main only effects 3/4 throttle and above.

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Caleb

Caleb

Well-Known Member
Location
Riverton
jentzschman said:
As I understand, it could be either your pilot and or air screw. I would also check the jets to make sure they are clean. If jets are clean then it needs a re jet. Check float levels first as I have been told that is very important. If that is in spec then start with the pilot jet and or check needle clip position. If I'm not mistaken, setting the air screw in conjunction with proper pilot jet will handle all the low end throttle positions. The main only effects 3/4 throttle and above.

Sent from my HTC One S using Tapatalk 2
Click to expand...

That's partially correct. Here's a chart that shows at what range in your throttle each circuit affects.

Carb-Jet-Ranges.gif
 
Cascadia

Cascadia

Undecided
Location
Orem, Utah
It's got a 165 main jet in it right now. Does that sound right for Utah Valley elevation? So going of your chart Caleb does that mean that my air needs to be adjusted?

I rode it around earlier today for more than 5 minutes. I rode it with the choke for the first little while. After about 5 minutes I turned the choke off. It ran a lot better once it was warm. It was barely cutting out. Still a little bit right off idle but as the bike got hotter it ran better.

Could it have anything to do with the motor just being rebuilt, new piston and all. The previous owner said he had it set to run a little rich because of that.
 
glockman

glockman

I hate Jeep trucks
Location
Pleasant Grove
Have you tried new gas? If it sat 1/2 empty for a while it had a chance to get a lot of condensation in the fuel. Also, your 4T doesn't have an air screw it has a fuel screw that does exactly the opposite of an air screw. I guess they both lean or richen the mixture but in the opposite application.
 
Cascadia

Cascadia

Undecided
Location
Orem, Utah
rholbrook said:
Tell me about the bike. Where did you buy it from? Where did you test ride it at? What was the temp the day you rode it?
Click to expand...
I bought it in SLC. I test rode it in the Avenues and it ran awesome. Never cut out once. The temp was probably about 50-55 the day I rode it. But the PO had also been riding it before I got there so it was already warmed up.
 
Cascadia

Cascadia

Undecided
Location
Orem, Utah
glockman said:
Have you tried new gas? If it sat 1/2 empty for a while it had a chance to get a lot of condensation in the fuel. Also, your 4T doesn't have an air screw it has a fuel screw that does exactly the opposite of an air screw. I guess they both lean or richen the mixture but in the opposite application.
Click to expand...
I haven't tried new gas but it was on m list. The gas did sit all winter but he said he put stabil in it and started the bike once a month during the winter. But I wasstill thinking I should probably empty the tank and start over fresh.
 
Caleb

Caleb

Well-Known Member
Location
Riverton
Cascadia said:
I haven't tried new gas but it was on m list. The gas did sit all winter but he said he put stabil in it and started the bike once a month during the winter. But I wasstill thinking I should probably empty the tank and start over fresh.
Click to expand...

Have you pulled the carb apart and cleaned it? I would do that along with new gas. Then reset all your jets and fuel screw. I bet it will run great after that. If it doesn't, what you may want to consider is getting a JD Jetting kit. He has instructions for the elevation you'll be riding. I've never had a bike that didn't run like a top after putting the JD Jetting kit in it. I believe they run about $80-$90.
 
anderson750

anderson750

I'm working on it Rose
Location
Price, Utah
You should not have to use the choke for more than a minute. If you need the choke that long I would say you have a clogged pilot. The air screw is going to have the greatest effect off idle and keeping it from bogging at that point.
 
Cascadia

Cascadia

Undecided
Location
Orem, Utah
I haven't taken it apart and cleaned it yet. I'll have to look up how to reset jets and fuel screw. Is there a good site for this? I was thinking about a JD jetting kit.
 
Caleb

Caleb

Well-Known Member
Location
Riverton
Based on JD's site, they are surely different. He offers a kit for the 96-99 (JDY012) and a kit for the 00-13 (JDY004). It looks like RMATV only has listed back to 2000 as you've seen though. I'll call RMATV tomorrow and see if they do indeed have (or can get) the 96-99 kit.
 
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