Need help tuning a rampage mt

[Vbzatty]

I bought a new rampage mt v3. I broke in the factory motor but then installed a 28.5cc kit, hpi filter and ddm exhaust. Now I can't even get the thing to start! I'm sure the carb is way out of tune now that it's flowing more air, but where do I start on tuning it? I gotta get it running before I can fine tune the hi and low needles, right? If i use starting fluid it will start then die which confirms it is a fuel issue.


Colby

 

[lightning73]

Double check your fuel lines, make sure you have the supply and return line in the right position. Maybe you just have them reversed??


And welcome to the forum!

 

[Vbzatty]

Didn't mess with the fuel lines, pulled the carb off and let it dangle.


And thanks!


Colby

 

[lightning73]

Do you have good compression? Or have you checked to see if its vapor locked?

 

[Vbzatty]

I got it started but it will only run with the choke fully closed. Open it at all and it stalls. Suggestions?

 

[RampageHopUps]

FROM the DDM Tech Page:


•How should I adjust the jets on a Walbro Carburetor (WA-167 / WT-603 / WT-668 / WT-257 / WT-813, etc)?


These carburetors require regular adjustment to ensure peak performance, and also to avoid an unsafe lean condition, which can prematurely damage your engine. If you find your top-end RPM's have fallen off a bit, or if you experience lagging or surging, it is probably time to re-adjust the carb jets. To ensure max performance and engine life, follow this procedure:


1) Locate the low and high RPM jets on the side of the carb - they are usually marked with a L and a H. Turn both jets completely CLOCKWISE ( to the fully closed position).


2) Rotate the Low jet counter-clockwise to 1 and 1/4 turns open.


3) Rotate the High jet counter-clockwise to approx 1 and 3/8 turns open.


4) Now, start the engine. You may need to turn the Low jet slightly one way or the other for the engine to start.


5) Adjust the Low jet as desired until the idle is where you like it. Turning clockwise ("CLOSING" THE JET) will produce a higher idle, and counterclockwise ("OPENING" THE JET) will produce a lower idle (and eventually flood and the engine will kill, if you turn it too far).


6) Open the throttle lever to full blast. Adjust the High jet until you get maximum RPMs. Note: this will probably be REALLY LOUD. Listen for the highest-pitched whine to tell you where max RPMs are hit. AFTER YOU FIND THE MAX RPM SETTING, TURN THE HIGH JET COUNTER-CLOCKWISE ("OPEN" THE JET) APPROX 1/16TH OF A TURN TO ENSURE YOU HAVE SUFFICIENT GAS/OIL MIX TO COOL THE ENGINE PROPERLY.


Note: The above are just general guidelines. You may need to adjust both the H and L screws once you begin driving, depending on engine loading, altitude, humidity, etc. The trick is to find settings that work well for you, and stick with them.


Here is some helpful information regarding common carburetor tuning problems:


If your engine stutters at full throttle and cannot reach full RPMs:


The high jet is too far open. Close the jet by turning it clockwise slightly, and then ride-test. If no improvement, repeat until desired results are achieved. Once you have found a workable setting, open the jet approx 1/16 of a turn to ensure sufficient fuel/air mix.


If your engine bogs out when transitioning from low speed:


The high jet is too far closed. Open the jet by turning it counterclockwise until you are at least 1 1/2 turns open, and then gradually close the jet until performance is as desired. Poor engine compression, blocked exhausts, and very heavy engine loading can all also cause bogging.


If your engine idles very fast and kills if you attempt to slow the idle:


You may have an air leak in your intake. An easy way to check for leaks is to spray the intake manifold and area surrounding it with WD-40. If the idle changes after you spray the WD-40, there is an air leak. Common areas for leaks are between the manifold and the cylinder, and between the carb and the intake manifold. Inspect the manifold, carb gasket, and intake gasket for cracks or other signs of damage, and replace if necessary.


If your engine idles but then slowly kills:


Your low jet is too far open. Close the low jet by turning it clockwise until a stable idle is achieved.


•What are the recommended carburetor needle settings for my engine?


DDM recommends the following tuning as a STARTING POINT for tuning your engine:


G230RC / G260RC / CY23RC / CY26RC / CY27RC / CY29RC / GP290 engines: 1 and 1/4 L, 1 and 3/8 H.

 

[DemonRC]

I got it started but it will only run with the choke fully closed. Open it at all and it stalls. Suggestions?

Choke fully closed forces fuel into the engine which is only used for starting. It will flood the engine evntually. Now if your car only runs with the choke closed that would lead me to believe that you low speed needle is way too lean and the engine is not getting fuel. The full choke is probably the only reason the engine is even getting fuel. Reset the needles to the factory settings like the guide says. You really need to do this everytime you change a head, carb, and sometimes even a pipe. 1 1/4 turns on the low needle and 1 3/8 on the high needle.

 

[yakrcnut]

i wouldnt recomend using starting fluid to start your engine that could lead to a whole new mess of trouble.

 

[bajadave]

They do have starting fluid especially for 2 stroke engines it comes with oil added to it.

 

[yakrcnut]

cool, well thats something new i learned today

 

[mp3jeep]

This video might also help, pretty much covers DDM tech page


http://www.whobbies.com/fullthrottle1.htm < you may want to watch


008: Starting and Tuning Zenoahs (8/18) (fwd 2:36 into it unless you want to watch an ad)