United Motors (fun terd bike) carb adjustment

[gottraction]

Ok so after selling the R1 i started going in 2 wheel denials. So i picked up a 2004 United Motors Dirttracker 125cc. 4 stroke. Got it dirt cheap lol. Problem is. the previous owner had a brand new carb installed at some motorcycle dealership and this thing bogs down when you give it full throttle like no other. ive replaced the spark plug/oil/fuel filter. Im not to familair with carbs since my R1 was fuel injected and so are most of my cars. it looks like one of the jets i guess is unscrewed some. This screw is no where near where i can get any type of tool next to it to adjust it. I can adjust the idle though. Is there someone that does these on the side or a shop that could help me with it or do it for a good deal? bike is only worth 500 in great shape. So im not wanting to sink 200 in a carb adjustment. Thanks

[Over TWO Customs]

Id bet I can get you a new carb for the bike for $30.

[gottraction]

yea i thought about just ripping it all. but this thing looks brand spanking new compared to the rest of the bike. i priced one on an authorized dealer it was over 200

[Sanchez]

There are several possible adjustment points, depending on the carb. You might be able to adjust the needle up and down. It might have an air screw or a fuel screw on the outside that you can adjust for small air/fuel ratio changes. If you need to make a large air/fuel adjustment, you can take it apart and change the jets. It could have both a pilot jet and a main jet. It might also have an accelerator pump (sprays an extra shot of gas when you open the throttle quickly), and that might be adjustable as well.

What did the plug look like when you replaced it?

[gottraction]

it was the usual dark smoke looking plug. by looking at the carb i only see the idle/air screw. there looks like there is a jet screw but the way it goes in you cannot really adjust it in or out without pull the carb off. i dont see any other adjustments on the carb so im stuck. i just figured i would have to pull it apart to adjust it from bogging down. but i guess i was wrong

[NiceGuysFinishLast]

Unless your carb is drastically different from the ones I'm familiar with, you won't be able to see or adjust a jet screw with the carbs in one piece.

[gottraction]

i can see it. its upside down. i can touch it with a pair of needle nose pliers lol. problem does the jet need to be screwed in all the way? how can i make a quick adjustment if i have to keep taking the carb off of the bike?

[wallypiper]

The only carbs I've worked on lately were the CV carbs on an SV. To change the jets or the needle position required disassembly of the carbs. You could adjust the idle setting or idle air screw externally but nothing else.

[Sanchez]

i can see it. its upside down. i can touch it with a pair of needle nose pliers lol. problem does the jet need to be screwed in all the way? how can i make a quick adjustment if i have to keep taking the carb off of the bike?

Don't confuse the jets with the air screw. The jet (or jets) are inside the carb, and you have to take it apart to change them.

On the outside of the carb, you typically find two adjustment screws. One controls the idle, and the other is either an air screw or a fuel screw. The latter makes small adjustments to the air/fuel mixture. It's for fine tuning once you have the correct jets. It may or may not make a difference if your particular situation.

[gottraction]

yea there are only 2. i know clearly one that is easy to get to is for idle/air screw. there is one other that is upside down. meaning i would have to be on the ground to loosen it or tighten it up. thing is the engine is in the way. So i really can't get to it unless i use needle nose or pull the carb. i guess i will just pull the carb and adjust that screw all the way in. i dont think they would design it that way if you had to keep pulling the carb to get it tuned correctly.

[NiceGuysFinishLast]

How about a picture? You don't understand the carb, and we don't understand your posts.

Jets are not screws. If it looks like a screw, it is not a jet. Idle adjustment and fuel/air mix are two DIFFERENT screws. Generally the idle adjustment is a large thumbscrew, so that it's adjustable with the bike running with no tools.

[wallypiper]

yea there are only 2. i know clearly one that is easy to get to is for idle/air screw. there is one other that is upside down. meaning i would have to be on the ground to loosen it or tighten it up. thing is the engine is in the way. So i really can't get to it unless i use needle nose or pull the carb. i guess i will just pull the carb and adjust that screw all the way in. i dont think they would design it that way if you had to keep pulling the carb to get it tuned correctly.

:LOL::duh:

OH, yeah. They would. Removing your carbs, taking them apart to change a jet, reinstalling them to test and see if the new jet is right, rinse and repeat. That's carburetor tuning. That's exactly how you do it.:cheers:

[Sanchez]

i guess i will just pull the carb and adjust that screw all the way in.

Nick and wally are correct. Also, if you adjust the air screw all the way in, the bike will not run at all.

If the bike was sitting for any length of time with gas in it, the jets are probably clogged. Pull the carb off, take the bowl off the bottom, and you should see one or two brass jets inside. Probably just one for a 125. Remove it with a flat blade screwdriver and soak it overnight in carb cleaner. Blow it out with compressed air and/or use the soft wire from a twist tie to clean it.

[gottraction]

i know it didnt make much sense on post. but i figured it out! thanks everyone!