ORIGINAL: Big Red*



one more thing that might be contributing to this is the rubber gasket on the back of the engine where the exhaust connects to is all torn up, and im missing the carb pinch bolt.

ORIGINAL: papy_yosh

Don't go further. Fixe your exaust pipe and the carb screw.
THese engines are really sensitives to air leaks. Fixes them all, reset your settings to manufacturer then try again. because of the location and humidity, you might want to start with 1 to 2 hours leaner on the both LSN and HSN.
Hope this helps.

ORIGINAL: bigdogkanicsar
i agree, humidity means moisture and when heated it creates a lean condition

ORIGINAL: skrilla



It has been a while since I ran in very humid conditions, but I'm pretty sure that higher humidity requires the needles to be leaned some, so it in effect creates a rich condition, not lean

ORIGINAL: bigdogkanicsar

actually it's just the opposite. one of the first things i learned in basic engines was that water(moisture) when you spray it in the carb of automobile evaporates creating a lean condition. causing the combustion chamber temps to rise rapidly and break up carbon deposits in the engine. while that's automotive , there is no difference here. water when heated turns into a vapor(air) which causes a lean condition. therefore you need to richen the mixture to even out the addition of humidity(moisture+heat=air).

ORIGINAL: skrilla



I'm talking about humidity, water already vaporized and in the air, not straight water. In the post you quoted above (by papy_yosh), he said the opposite of what you said, that the OP should lean the engine, hence the humidity creates a rich condition. You said you agree with him, but your statement contradicts what he said. I'm thinking if the air is full of moisture, then there is less oxygen available. When you decrease the amount of available oxygen in your intake charge, you need to compensate the fuel charge accordingly, which means less fuel, ie, leaner mixture. So, higher humidity creates a rich condition

As for spraying water in an intake, when it goes in and evaporates, it displaces oxygen, causing there to be less available oxygen, so less fuel is needed in the combustion chamber, so it pushes it in the rich direction. This is just my rationalization of it, don't claim to be an expert on the subject

Also, what do you mean by 'water when heated turns into a vapor (air)'? I know it turns into water vapor, something inflamable and useless in an engine, but 'air' implies simply that, air...oxygen, nitrogen, the stuff in the atmosphere.

ORIGINAL: bigdogkanicsar


yeah i didn't really read what he wrote, but noticed it afterward. i don't want to drag this out like the last time you and i started postin' on the same thread.

water turns to steam, and steam is indeed inflamable. however, when i attended auto tech, one of the first things my instructer showed us was a way to raise the combustion temp by spraying water into the carb, and i wouldn't have beleived it if i hadn't seen it for myself. it does indeed raise the temp and to watch the carbon coming out the exhaust made a believer out of me.

on another occasion i lived in virginia with 85% humidity and the only way i could keep my RS4 cool was to run it pretty rich to offset the high temp of the engine caused by humidity. the same car in cali some time later in a place where there was only 15% humidity i had to lean it out to get it to warm up.

so, 6 of one and half dozen of the other. now i have a buddy who lives in va. with a jato and he says he's got to richen it up on the days after it rains and a little leaner if it doesn't rain for a few days.

ORIGINAL: skrilla


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Water injection does not raise combustion chamber temperatures, it lowers them. Here's a basic expalnation: http://en.wikipedia.org/wiki/Water_injection_(engines)

ORIGINAL: bigdogkanicsar

ORIGINAL: skrilla


If the outside air temperature was 115°, then that is clearly the sole reason you had to richen it. On warmer days we sometimes have to over-richen the mixture to keep the engine temperature down. However, with high humidity, there is less available oxygen in the intake charge, so to adjust for that you need to lean the mixture. Unfortunately, high air temperature and high humidity often occur at the same time. So while very high temperature outside forces you to richen some, high humidity forces you to lean some, creating a pretty tight tuning window. It's pretty much a double whammy. You want to keep it cool but you also want to it to run good. This is one of the reasons I am not a big fan of running on very warm humid days, not to mention standing outside sweating my arse off. We only have a week or two of that (90+ degrees, 80%+ humidity) here in central Indiana, if at all.