fuel mixture questions

[Nitroaddict]

I have a rossi .12 in my NTC3. It seems like it is running excessivly rich, bogs down when accelerating from a stop, lots of smoke. But when I lean it out a bit - it gets too hot ( 270degrees ) and sputters at WOT. Am I just not finding the happy medium, or should I adjust something else other than the HSN? I did the punch test, and the LSN seems to be set correctly. It is driving me crazy - I really want to get this engine tuned in correctly. Any help would be appreciated.

 

[mjime714]

I had that problem with my rb. the bog from a stop is because you are starving the engine of fuel at the low end. You need to richen the lsn to remidy this. Do the pinch test on the fuel line to the engine. If it revs up for a few seconds then dies, your good. If it takes more than 5 secs to die, you are running too rich. If the car dies almost imediatly, you are too lean.

I also think you are running lean because of your temps.

Hope this helps

 

[Nitroaddict]

the temps indicate that i am running lean. But i have excessive smoke coming out of the exhaust from idle all the way up to WOT. Wouldnt that indicate a rich mixture? The sputtering at low speed means it is too lean? I thought when it coughed like that it was drowning in fuel? maybe that might be part of my problem.

 

[mjime714]

If there was too much fuel, the engine would just die. What happens if you are too rich is you flood the glow plug and it puts out the light.

Your LSN may be lean, but your HSN may be rich, or rich enough to spit out smoke.

When tuning, you can lean out the hsn, but to compensate, you must richen the lsn a little so you dont starve the low end. The hsn does effect the low end a little, but not as much as when you play with the lsn.

You engine does have a lsn right? I hope I'm not jumping the gun without knowing if you even have what I'm talking about.

 

[Nitroaddict]

yes - i have both a LSN and an HSN. That might very well be the problem then. the LSN is too lean - and the HSN is just a lil bit too rich. Could this also be causing the following problem?

the idle set screw had to be set higher, because with it set so that the clutch wouldnt engage - it would stall. To allow it not to stall, the ISS had to be opened so much, that the car would move forward alot, without heavy drag brake.

 

[mjime714]

The lean low end may be the problem. Reset the idle to the thickness of a match book cover. Richen up the lsn and see what happens. I had a problem where if I lean out my old yokomo .18 engine, it would engage the clutch. I richen it up and problem solved. That was a single needle carb though. I come back to believing that the problem is a lean LSN.

Remember, I am only speaking from what I had to do with my experience. It maybe different with yours, or I may be flat out wrong because cannot hear, or see how your mill is running.

good luck