Hi All, been reading some of your forums with great interest as I'm a newbie to Nitro R/C.

I need some of your expert help.

I have just purchased 2 RTR nitro buggies, just hobby stuff not into racing or super hi tech etc. just take these things accross to the park with the lad to have some fun.

I have had my up's and downs with both cars but seem to have both running pretty well now, both are run in, and start up and run well.
My question is .......

Both car's instructions indicate running fuel mixture so that you can place the palm of your hand on the head and leave it there for "no less than 3 seconds" or the car is running too lean .

Thats great in theory but running the cars even at what I know is very rich settings (lots of smoke and take off bogging) after running around for 3/4 of a tank the heat on the head is well past leaving your hand on it for more than a split second. From what I'm starting to read in forums I'm better to ignore the temp and go by the car's actual running.. is this correct ???? Should I tune so the car runs well and not worry about how hot the head feels ????



Thanks Scooz.

You shouldnt worry too much about engine temps. There are a lot of people that totally rely on temp guns, etc. You should know if your engine is running too lean if it starts conking out, stalling, not enough smoke from the exhaust. Just tune for performance, not temps.

Cheers, Dave

well said, davpty. yes, do not tune for some "magic number". as long as the engine runs well and consistantly, you should be fine. also, as you gain experience, you will start to learn what each engine "prefers" in terms of a proper tune. i cant really explain this since it always seems to be that you develop a relationship with each engine as time goes on. then it becomes much easier to tune once you know what it likes.

Okay Thanks guys appreciate the help.

So basically dont worry if the head is bloody hot to touch as long as the car is running well and doing all the things that it's supposed to in accordance with being tuned correctly. From what I read these lil cars run around the 200 + celsius range so I'm pretty sure thats gonna feel damn hot to the finger tips even when the cars running perfectly.



Thanks Again Scooz

200+ Celcius is way too hot. 100 - 120C is more like it.

Okay thanks for the input,

So the car runs nicely, starts well, doesnt bog down at takeoff, doesn't lean out at throttle, idles well, blows a nice little stream of smoke under throttle.

How do I know if it's running too hot ? without having to run out and buy a temp gun or change over my fail safe. If I bring the car in 3/4 of a tank later and touch the head and it feels very hot to touch is that too hot ?

Should I forget the touching bit altogether and just rely on what the car runs like ?


Thanks Scooz.

scooz

Do the spit test .. place some spit on ye finger and straight [ thin layer don't overdo] on top of the cooling head. It should sizzle for 3/4 seconds .That should be about right .If it dries off in less than a sec then temps are over 140C. Which is too hot for most motors

If it doesnt sizzle or takes longer than 6 seconds to dry off it's not hot enough too rich.The rest you can just listen to the sound of the motor when running.Don't always assume the motor is rich.. sometimes air bubbles in the fuel line may make a motor sound rich or vice versa.You got to flush them out with a few blips.And go another round.

That is correct, you should tune your engine for performance (i.e tuned perfectly), and not tune to obtain a specific temperature.

ive never done the spit test before cause normally an engine will tell you if its even just a little too lean. since it doesnt like it it will start running very poorly and roughly because its not getting enough lubrication. normally the same thing happens if its too rich but instead of running roughly it will bog down and wont reach max rpms.

You should not rely on temperatures, only if you are not a good engine tuner. Although you should egt a temp gun. First tune your engine to performance. Start with a slightly rich setting. Then lean out the high end needle in increments of an eighth of a turn. Keppp doing it until you don't see a performance gain. Then richen by one-eighth of a turn. Make sure engine is wormed up befroe changing needels. Look at temp woth temp gun. Write down in a RC Journal what outside temp and engine temp. As outside temps rise the engine temps will also rise. Write down outside temps and humidity along with engine temp. Use that info for future tuning in same conditions. REMEMBER, ALWAYS TUNE FOR PERFORMANCE, NEVER ENGINE TEMPERATURES. I know what I am talking about I work at STAMPY'S COOL STUFF, it works every time.