Need more tuning help

[Dewd]

The new radio setup has forced me to re-tune, as I lost the idle setting from the original radio. So I'm having trouble again - I can get it running eventually, but when it stops, it won't start again. I start out with stock settings, and use a .040 drill bit to make sure the closed-throttle setting is correct.

So please help me out - I'm trying to recognize tuning keys here. Some observations:

1) Sometimes once it starts (cold), it dies as soon as I remove the glow igniter. Leave the igniter on for a few secs, it stays running. Too rich I'm guessing, but which needle? Low speed would be my guess, but everything I read says don't touch it.

2) I lean the high speed until I finally get it to run, and it runs ok. I do some full-throttle passes, checking the temp between passes. Eventually, it gets up around 280F. So I richen it back up about one full turn till the temps stay between 220-250. After it runs out of gas, I fill it, prime it, and it will not start until I lean it back out that full turn.

3) Sometimes when cold and I'm attempting to tune from stock settings, it will idle for a short time, then get rough right before stalling. Is this "4-stroking"? Which needle do I turn?

 

[jcam54]

these links should help you some!


http://www.youtube.com/watch?v=U4uRt4HHFZM

http://www.youtube.com/watch?v=Nb3pR7-gQzk&feature=related

http://www.rchobbies.org/cars_eng-tuning.htm

 

[nickmind]

Those vids are good to learn off of.

1) Dewd, here is a trick I use. Especially for newer engines (even 2 or 3 tanks after break-in), when you get the engine running leave the glow starter on, but put your finger on the head. Once the head gets to the point of hot (like oven hot, don't burn your hand) then take out the glow starter. Sometime you can pre-heat the head with a heat gun or blow dryer. That makes the engine start faster. The idea is to keep the glow plug hot as you can.

2) Start at factory settings. Then get the engine started. Once started work only with HSN make sure you see lots of smoke. 280 is not bad (its not the ideal temp), but you also are not going to break the engine. Make sure you use 1/8th turns or smaller, and let the engine get use to the setting. Then start with the LSN

3) Same as 2. But remember small adjustments at a time, and let the engine get use to the setting. And Lots of smoke! is good.

My two pennies.

 

[oregonmud]

My engines don't even wake up till they hit 260-280. 1 full turn richer from that temp is too much if you ask me. I don't richen the engine unless the tune sounds off or the temps get over 290.

 

[Dewd]

My first gallon of gas was Traxxas Top Fuel, 20%, and people have said that fuel sucks. So I picked up a gallon of Sidewinder 20%. Maybe it's all in my head, but the truck fired right up today, none of the pain in the *** having to lean it way out to get it to take throttle, then richen back up to keep temps under 300F. In fact, from the last hot tune from Traxxas fuel, it was great. It got a little hot after some long full throttle runs, but I only had to richen it 1/4 turn to get temps back in line. Unfortunately, I broke a front lower arm within the first half tank, so I didn't get to enjoy it for very long, but it was running beautifully up to that point.

Thanks for the replies, they definitely helped :resp:

 

[nickmind]

I broke a front lower arm within the first half tank, so I didn't get to enjoy it for very long, but it was running beautifully up to that point.

How did you do that?

I have owned 3 savages, and trust me I have ran them into carbs, telephone polls, and crazy jumps. I have yet to break an a-arm. These Savages are harder to break then most. Now, on my second run of my CRT's life I broke an a-arm running into the carbs after a radio glith.

Just askin.

 

[Dewd]

How did you do that?

I have no idea, other than general abuse. There are a lot of large hidden rocks in the field I was running in, so I may have whacked one at full speed. What "broke" was the front of the hinge split, causing it to end up above the hinge pin. Whatever caused it had enough force to deform the plastic. I can't seem to get it bent back down to shove the pin back thru, so I'll just replace it.