drdenny

My Feedback: (1)

Well, this one is stange. I was running my Sportmaxx a few weeks ago, and everthing seemed fine. However, when I started it up tonight, I have several things going wrong. First, the engine will get to half throttle and quit! It just flat out stalls. The other thing is that the barrel in the carb is not fully seating against the LS needle. It looks as if it is binding in the carb barrel. If I move the linkage with mt fingers right next to the carb, I can make the barrel retract. This is a stock 2.5 engine. I haven't switched fuels(traxxas 20% top fuel), and haven't had any crashes that might contribute to this issue.
Also, sometimes when I first give it alittle gas, it will stall. I have reset all the needles to factory position, and even added some more lean mixture to it so I have a good smoke trail from the exhaust.
Any ideas???[]

jayhawk25

Even though your at factory settings you still could be a little rich. But before you lean it out and overheat I would try a new glow plug. Sometimes it will work enough to start the engine and run but will get fouled when you apply throttle. Your low speed needle may be to rich but I would try a glow plug first. Let me know if this works.

jefx

Ditto on the glow plug ^. An easy way to test plugs is with a glow ignitor. They're cheap, and they're worth owning just for that reason alone. As far as your carb slide sticking, have you removed it? This seems to be a frequent problem with this engine. By design, the carb has a tendency to stick, because the linkage doesn't pull straight back on the slide. It pushes on the slide at an angle, which causes the slide to rub against the carb body. Idealy, the carb should be aligned so that the linkage runs as parallel with the slide as possible, but there isn't much room to do this. You may just have to take the carb out, remove the boot and spring and slide and clean them. Then coat the slide in after run oil, or even a dab of petroleum based grease. If you use the grease, only put it on the part of the slide that is under the boot, and do it after reinstalling the slide and spring.

jefx

Another thing, you're having mixture problems and carb sticking problems at the same time. Maybe the carb wasn't tightened down all the way, and the movement of the throttle linkage is causing the carb to twist. This would give you an air leak (possibly the reason for stalling) and could also cause the carb slide to hit the ezstart motor or slipper clutch nut (possibly the binding problem).

Zeroc

the carb sticks,and thats that.i've tried everything to stop mine from sticking,first i got a car rebuild kit from my lhs,nothing,the ni got a carb body,nothing,then i replaced them both at once,nothing.finally i turned it out a bit towards the tuned pipe side of the truck and it worked for a while,i dont know why it did.but within a month and a half it was sticking again.just buy a stronger throttle survo,problem solved.[:-]

drdenny

My Feedback: (1)

Thanks for the ideas guys. As a FYI - I did install a brand new glow plug, and replaced the fuel lines. I'll look at the servo, and Jefx... you say the carb might be out of alignment? I'll look at that as well. What about the seal under the carb? I will also lean it out and see what that does. Thanks for all the tips!!

jefx

You should put a thin layer RTV around the base of the carb, this is a frequent place for air leaks.

jayhawk25

I agree with the RTV. But use very little. Your carb should also be turned a bit. I.E. not all lined up to the engine. The TRX 2.5 carb sits at a slight angle to the motor. traxxas.com can show you how it should look. Let us know on how everthing is going.

GVFD29

Just get rid of the motor. lol...buy something bigger. I'm not allowed to mention the one I would buy but maybe someone else can.

drdenny

My Feedback: (1)

Will do what you guys mentioned...Will get back to you. Thanks again for the help!

mgreen

Also, I wouldn't start messing around with the needle setting that fast. If it was running last time you had it out, it should start. It might be abit hard to get it going but it should still work. You might have to adjust the idle screw, but once you get it going, start driving it right away so it doesn't stall? You want the motor to heat up and then you make adjustments, if you have to. A cold motor will always be alittle bit harder to start: expspeialy if your new to tuning them. You should have a temp gun because that will give you some ideas on if your motor is running to lean or rich.

drdenny

My Feedback: (1)

I most definitely agree with you. Now I have to wait for the weather to break so I can get back out.
Thanks.

allen0622

Picco P2 www.werksracing.com[sm=RAINFRO.gif]

drdenny

My Feedback: (1)

Well guys, I got some of the bugs worked out. I loosened the carb, re-aligned the linkage, and re-set the HSN. Now its running fine on the top end. However, it still stalls when it is near idle. Alot of times it seems the idle is a little fast, and yet when I give it gas, it stalls. I'm wondering about the LSN settings. I did set it flush as per Traxxas, but like I said, it will stall when you put the coals to it. Am I too rich or too lean????
Thanks again for all your input.
Denny

jefx

Well if the idle is a little erratic, and it's high sometimes and still stalls, then it sounds to me that it is a little lean. Richen it 1/8 turn and try again. If it still stalls, try another 1/8, etc.

drdenny

My Feedback: (1)

Thanks Jefx. I ran out of daylight, so will give it a shot tomorrow.

jefx

Alright, let us know how it goes.

coupedit03

I am having the same problem. What do I need to richen, the LSN or HSN? and Which way is richening it? CLockwise or counter?

drdenny

My Feedback: (1)

On the idle,(low speed) it's the LSN. If it's WOT, it will be the HDN. I am talking about the low speed settings that need to be adjusted at this time.

drdenny

My Feedback: (1)

To richen mixture, you turn it conter-clockwise. To lean, it would be clockwise.

04TMAXX

what if it cuts off after a high speed run, but runs good everywhere else..whenever i slow it down and let all the way off the throttle it dies??

drdenny

My Feedback: (1)

Thanks whats happening with my S'Maxx right now. I just had it out, and can't seem to get the low end adjusted right. Gonna keep messing with it!