i didnt have a chance to get out today. the truck was stripped so i just put it back together. i`ve been having some suspenion problems with this truck too. i`ll save that for another day lol

Rsickles- what is the 10-15 second test on LSN? i know of the 3-4 second pinch test

SDtech- how much smoke do you want? what is ideal

is there anything i should be looking out for when im getting close to the perfect tune? i know the main signs of rich and lean, but once you close to that sweet spot, what are the tell tale signs to know im close. its so easy to eend up in the opposite direction, and get frustrated.

^^^ The 10-15 second test on the lsn is when you run a couple laps, then come in and let the engine idle for 10-15 seconds, then punch it. If it clears out nicely and has a thin trail of smoke, your lsn is set nicely.

Since you don't know what you are looking for on smoke, always start out on the rich side. It's hard to describe how much you are looking for. I would describe it as a thin trail, but constant. It's really a trial and error thing. This is where your temp gun will come in handy. Run it for a minute or so, note performance/smoke and temp it. Then lean it out a little and run it another minute or so, note how much smoke and temp it. Repeat this until you are happy with the performance and not superhot. Note how much smoke this is and remember it.

I get worried at about 280F and will richen it up some. But some engines like to run hot, that's why there's no magic number. The alloys used in these engines start losing their properties at about 300F.

Here is Jared Tebo showing you how to tune on youtube. This should help you. Watch this, mess with your nitro vehicle and do what he says, then watch it again.

http://youtu.be/iwzcWLKKU0I

This is backwards from how I tune (he does HSN first), but shows how much smoke you are looking for.

http://youtu.be/oSmMzpZM_As

Thanks for the help guys.

I just had the cars out for 30 mins or so. I got the car running pretty good, the temp was around 208F, I was in my yard and on the sidewalk so I never really had any where to open it up.

I had the truck running awesome the last time I drove it, but for some reason when I took it out today it was running extremely shitty. Soon as I started it, the motor revved as high as it possibly could. The settings were really rich, bog soon as I touch the throttle. The fumes were so bad they burned my throat and sinuses.

First thing i did was closed the idle gap. I leaned the HSN, And the idle was very high, so I lowered it, and leaned some more. I would have to close the idle gap every time I leaned HSN. the acceleration was getting better, but know where near where it should be. it was running around 210F

this is where i kind of get lost. and im thinking should i lean the HSN more, should i touch the LSN, Rich or lean, should i turn the idle down? but really im clueless. and have no idea what to do

anyway, i think i tried to richen the lsn to get the idle down, and took it for a drive. pinch test was good. but I still could not get the same snap off the line it had the last time I drove it. and now soon as i touch the throttle, it would stick wide open, i would have to slam to brakes to stop it. my neighbors started coming outside, and i am beyond frustrated so i shut it down.

when i read up on how to tune, it makes perfect sense, but when im actually doing it, my brain goes into retard mode. i need one of those books for dummies wit pop up pics and shit haha

Your tune should not change that drastically from day-to-day, unless weather conditions are way different.

You might have something else going on if the tune was that bad from one day to the next. You might have an air leak somewhere, an issue with your clutch or bad fuel.

Air leaks are one of the most frustrating things in dealing with nitro vehicles. Can be hard to find. If my "tune" changes very much from one run to the next, I start searching for signs of an air leak before I make huge changes to the needle settings. Once you have it running well, you shouldn't need to touch the needles very much run to run or even day-to-day. Most common places for air leaks to develop are fuel lines, fuel tank lid seal, around the base of the carb and the engine backplate. Also check to make sure your head bolts are tight on the engine.

I've also been a part of a number of "tuning" issues that ended up being a clutch issue instead. Worked with a guy all day once trying to get an engine running right. Before we started, I asked him when the last time he re-built his clutch was. Told me it was brand new. Came to find out that the clutch itself was new, but he had put the old clutch bearings back in and they were over a gallon and a half old. Caused us fits. Replaced the clutchbell bearings, went through a quick tune up and it ran like a dream.

Last issue is fuel. I hope you don't store it in your garage? It is old? Nitro fuel is hygroscopic, which means it attracts and retains moisture from the air. If your fuel is old, or has been stored in your garage, it might be going bad and causing part of your issues. Also, never leave fuel in your tank after you run. Dump it out or run it out, just don't leave it in there. If you had old fuel left in the tank, that might explain why you had the issues you did the last time you fired it up. Could have taken on moisture or gummed up your fuel lines, causing erratic running.

I have a quick question about idle: what causes loading up at idle, so that it cuts out after 10 seconds or so - too rich LSN, too rich HSN, or too big an idle gap?

Assuming engine is run in;
Loading up at idle leading to cut out = LSN too rich.

I always set idle gap at 0.5-0.7mm and leave it there. That is one variable out the the equation , then tune LSN so it idles nicely and consistant. Use LSN to control idle and forget about the idle gap once it's set.

Then work on HSN. If you need to lean HSN a lot then you might have to richen the LSN a bit again (you will notice because idle will get higher/faster).
Btw: If after a high speed pass the engine starts to stutter/machinegun it usually means the HSN is too lean. Richen it 1/8th turn and it should go away again.

i took them out to a wide open parking lot today. i got them running great now. it was way easier noticing the changes in a big lot rather then in a small yard. im pretty sure i do have an air leak. i've been noticing a dozen or more tiny bubbles in the fuel line.
i checked both lines for leaks or pinholes, cut off 1/8 of each hose end. i removed the pipe and seen the rubber that connects to the manifold side is way to big, i used a bigger zip tie and tried to blow air through, it seems sealed. i might have to break out the sopapy water to be sure.

the fuel is super old lol like 07-08 old haha, and it was stored in the garage, actually in the very back corner of a baby barn beside the garage. 2 brand new gallons with outh the seal cracked. no chance i was chucking them. especially when the cloest hobby swhop is a 6 hr drive. the color is still good. its bright pink, i left the little fill bottle out in the sun for 2 days and it turned like brownish red. i didnt use that tho.

Do most tune with the venturi in or out? assuming idle gap is set does it matter?

Venturi in when tuning venturi out when setting idle gap

If you have air bubbles going from the tank into the fuel line then you most likely have a split inlet pipe inside the fuel tank. I know my kyosho likes to do that if i case too dang many jumps. Lol. Replace your fuel line with new stuff then if the issue persists replace the tank.

My be important. What kind of engine is this and what car.

I just replaced all the lines and it is still happening, ordering a new tank and hoping this solves the issue.

It's a Durando 408 with Werks clocked b5 and JP-2 pipe/BuKu clutch.