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-   -   [iston color, exhaust color (https://www.rcuniverse.com/forum/car-nitro-gas-engines-269/1702518-%5Biston-color-exhaust-color.html)

zimzalahbim 04-08-2004 07:11 AM

[iston color, exhaust color
 
i just read a thread in another forum, and someone was talking about brown streaks on the top of the piston, or inside the stinger being an indication of running too lean. i know that the piston in my hyper .21 is brown, but she runs with a thick stream of smoke always. i also just finished breaking in a nova rossi .12 engine, and the aforementioned brown stuff is in the end of the stinger of the pipe. i couldn't think that this engine was running too lean, because during the hear cycling phase of break in, brown, unburned oil poured out of the pipe. could the engine run too lean with all that oil pouring out? i do not have a temp guage, but monitor the engine temp, crudely, by spitting on the engine. i use 25% tornado fuel, bought in korea where they mainly only use this brand of fuel. anyhow, just wanted some confirmation that maybe the brown color symptom could be bunk. thanks

slodsm 04-08-2004 09:21 AM

RE: [iston color, exhaust color
 
Yes, color is really no indication of anything, oil stains are what causes the color. If you tear down a motor run with Blue Thunder, you will find everything the fuel touched on it path through the motor has made a dark dark green to brownish stain. Now if you see tiny pits in the top of your piston, that would be an indication of detonation which is a by product of running too lean, but the color itself really is not.

Homebrewer 04-08-2004 03:21 PM

RE: [iston color, exhaust color
 
Smoke is not necessarily an indication of whether you are lean or rich. More and more fuel companies are making fuels that produce less visible smoke to preclude potential environmental issues that have surfaced in other countries. Also, different brands produce different levels of smoke.

skyneverdie 04-09-2004 05:36 PM

RE: [iston color, exhaust color
 
:O my Savage with stock motor....the piston surface is all black, the underhead is all black...... but the temperature is around 280 which is normal...

any clue?

HondaCRX 04-09-2004 07:03 PM

RE: [iston color, exhaust color
 
either still lean, or lack of proper ventilation;)

RCtoughGuy 10-16-2010 11:17 PM

RE: [iston color, exhaust color
 
color on the piston can be an indication of bad tuning

ORIGINAL: zimzalahbim

i just read a thread in another forum, and someone was talking about brown streaks on the top of the piston, or inside the stinger being an indication of running too lean. i know that the piston in my hyper .21 is brown, but she runs with a thick stream of smoke always. i also just finished breaking in a nova rossi .12 engine, and the aforementioned brown stuff is in the end of the stinger of the pipe. i couldn't think that this engine was running too lean, because during the hear cycling phase of break in, brown, unburned oil poured out of the pipe. could the engine run too lean with all that oil pouring out? i do not have a temp guage, but monitor the engine temp, crudely, by spitting on the engine. i use 25% tornado fuel, bought in korea where they mainly only use this brand of fuel. anyhow, just wanted some confirmation that maybe the brown color symptom could be bunk. thanks

RectalExam 03-17-2012 05:03 PM

RE: [iston color, exhaust color
 
bump


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