Lean symptoms in two stroke dirt bikes include bogging or gagging and falling flat on its face when you crack the throttle, not running unless the choke is on, or having very harsh transition from a weak mid range to strong top end. Adjust your metering rod. Cracking the throttle is not enough to activate the power jet, so do not adjust it.
If you are riding on the pipe and your bike feels flat, down on power, or excessively "pingy," your power jet may be lean. Open the power jet 1/8 or 1/4 of a turn. A standard dirt bike should not need a power jet that is open more than 1 1/4 turns. If you are riding a snow bike or dunes where you are wide open for extended periods of time with excessive load, you may need to go to 1 3/4 turn open, but not more than 2. Dirt bikes running gasoline will never need a larger power jet.
A rich two stroke will often stutter or fell blubbery before taking off, it could smoke more than normal depending on your fuel mixture, or load up at low RPM. The RPM returning to idle when you close the throttle quickly will often sound choppy, dropping down, then hitting high, before dropping back down. We never recommend tuning around this if the bike is otherwise running well because engine performance is determined on accel, not decel, Normally you can adjust it with the idle mixing circuit screw, You can get very good throttle response and very good bottom torque output by adjusting the idle mixing circuit screw, It should be noted that while adjusting the idle mixing circuit screws, you also need to adjust the idle screws. Each adjustment of the idle mixing circuit screw cannot exceed one-eighth turn, and each adjustment of the idle screw cannot exceed one-quarter turn, A richer mixture will get better throttle response and bottom torque output. If you are not satisfied with the power performance after adjusting the idle mixing circuit screws when the throttle is below one-half, You may need to adjust the metering rod. however, it can usually be minimized by going 1/4 turn leaner on the rod. This is the same for "pipe bang" when riding down a road (the bike loads up when pulling a large vacuum at a low throttle position in a high gear, then burns off the excessive fuel incosistently).
1:How do I adjust the metering rod?
Turn clockwise to get richer, Turn counterclockwise to get leaner, Each adjustment is a quarter turn, The metering rod will become longer or shorter as it turns (.006” per ¼ turn), Until the sound is crisp and excellent throttle response.
2:How do I adjust Power Jet?
Turn clockwise to get leaner, Turn counterclockwise to get richer, Each adjustment is one-eighth turn, Until excellent top power.
The power jet is used to fine tune your top end and works like a faucet. If you turn it to the left, it opens the valve and richens it. If you turn it to the right, it closes the valve and leans it out. Tuning this has nothing to do with your idle or low to mid-range throttle response. NEVER ride with a closed power jet. If you are riding dunes, deep sand, outdoor motocross, or snow where you are wide open for extended periods, we recommend going ¼ turn richer to keep your motor cool. The fuel level in the line will be even with the level in your float bowl until the power jet is activated. Cracking the throttle open is not enough to activate the power jet. The motor must be pulling a sufficient vacuum with the slide height over the bottom of the jet nozzle for about a second. Trying to activate it on a stand will usually not work because it is not under enough load to pull enough of a vacuum before revving out. Most two stroke dirt bikes running pump gas will come with the power jet open between 3/4 of a turn and 1 1/4 of a turn from bottomed out.
3:How do I adjust fuel mixing screw?
Turn clockwise to get leaner, Turn counterclockwise to get richer, At the same time, it needs to cooperate with the adjustment of the idle screw, Idle speed cannot be lower than 1,500 – 2,400 RPM ,Until excellent throttle response (Four-stroke version carbs).
4: Why is my bike bogging?
If you quickly open the throttle when the engine is idling, the symptoms of the engine will stop running, and the motor gags like it wants to die, your rod is most likely too lean. If it gurgles or stutters, it is too rich. First of all, you can adjust the screws of the idle mixing circuit. In most cases, you can get very good throttle response and bottom torque output. If you are still not satisfied with its performance after adjustment, you can try to adjust the metering rod to improve. Adjust it in ¼ turn increments. "sweet spot" is often a window that ranges about 1/2 turn inbetween being too lean and too rich where the power the strongest and the throttle response is crisp. By making large adjustments, over 1/2 turn at a time, you risk missing the sweet spot and going from too lean to too rich, or vice-versa. This is why small adjustments are always recommended. Some overly rich symptoms often overlap those of a lean condition, and make diagnosing it difficult. If you find yourself lost, your starting length is on your manual.
5: Why is my top end flat?
If you are running wide open and your bike feels flat, turn out (richen) your power jet in 1/8th turn increments until it runs how you want it to. If it stutters or gurgles, turn in (lean) your power jet 1/8th turn increments.
6: Why is my bike hard to start?
Normally, this is because the idle mixing circuit screw and idle screw are not adjusted to the best condition, You don’t need to adjust the metering rod. During cold start, you don’t need to use the choke first. You can try to rotate the idle screw counterclockwise one turn and then start and wait for the engine to hot, restore the idle screw back. If the weather is very, very cold, Use your choke, If you believe your choke is not working, prime the carb by plugging one vent line and blowing in the other until you see a small amount of fuel go through the power jet line, start the bike and, once it is running, pull the choke up. The RPM should fall dramatically.
7: If I see smoke and spooge, Do I need to adjust the metering rod?
No, There are many types of 2T engine oil. These phenomena may have something to do with them, but this is not important. The important thing is that if the engine works well, then ignore it.
8: Should I change my oil mixture?
We recommend you to use fully synthetic 2T engine oil. Mix your oil according to the oil manufacturer’s specs.
9: Why does my bike sound rich, but run great?
In actual riding, sound does not represent performance. What is important is performance, not whether the sound is good or not.
10: Why does my bike run with the choke on, but not with it off?
Your bike is way too lean.
11: I'm going to a high compression head, what do I need to change?
Try riding it with your current settings first. Minor rod tuning may be required based on how aggressive the head is.
12: Why I forgot to turn off the fuel tank switch, my engine is full of fuel?
A fuel filter must be installed between the fuel tank and the carburetor and replaced once a year. Please turn off the fuel tank switch after riding, and turn off the fuel tank switch when using a trailer for transportation. If the fuel fills the entire engine, First turn off the fuel tank switch, Remove the spark plug and press and hold the stop button(This step is very important, otherwise it will cause a fire) try to use the starter motor or kick to get rid of the fuel in the engine, Then clean up all the spilled fuel and clean the spark plugs and reinstall the spark plug, If necessary, clean the Needle Seat Valve of the carburetor. When re-opening the fuel tank switch, please pay attention to observe the fuel level in the float chamber(BIKE must be upright), The best liquid level position should be in the middle of the letter "XTNG", If not, please adjust the float until the best liquid level.