did a plug chop...

89blaster89

Member
Aug 26, 2011
4,739
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90
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Pacific northwest, washington
well i did a plug chop with the mods i have in my sig but i had a 320 main jet in 32.5 pilot and stock needle position, my elevation is 250 feet above sea level, and well i went 1-5th gear, i barely got into the powerband, and i got a very light brown color, im not lean, i think im just not getting into the powerband enough...i dont have much room to get into the powerband much but ill try again...
 
also, now that i put in the 320 main i think it might be rich (will plug chop soon to find out) welli was just letting it idle and warmup for like 5 or 6 minutes, then ride around in like 1st or 2nd gear, the when i stop it starts to turn off, so i took the plug out cleaned it off and now its fine, so is that just from being rich right now and excesive idleing?
 
update: i just tried to do a 4th gear WOT plug chop, i couldint hold it long though at all, i like hit a bump and nearly flew off lol, anyways i didint really get a reading again but light brown, everytime i pull the plug out from riding around in 3rd or so its all shiny and wet, and im fouling plugs... so i no im rich but i just cant get a good reading on the plug, i have in 320 main 32.5 pilot and my elevation: 250 feet above sea level. and it sounded like it was fourstroking from being rich but i couldint tell, i might take a quick video
 
Hey, I'm sending your scoops out today. Do you have other sizes of jets? I can send you a 280 or 290 main, if you need it. I'll PM you my number. You can text me and let me know.
 
yea i had one sucessful plug chop awhile ago though, i was a 300 main and a tiny bit lean so im thinking move my main to 310 and itll be good? my elvation i very low here so i have bigger main jets...

Actually, low elevation generally means you need LEANER jets. Richen as you go up.

LEAN your jets if: warmer weather, lower altitude, less premix oil, larger displacement, more air flow, more humidity.

RICHEN your jets if: colder weather, higher altitude, more premix oil, smaller displacement, less restrictive air filter.
 
Actually, low elevation generally means you need LEANER jets. Richen as you go up.

LEAN your jets if: warmer weather, lower altitude, less premix oil, larger displacement, more air flow, more humidity.

RICHEN your jets if: colder weather, higher altitude, more premix oil, smaller displacement, less restrictive air filter.

by richen you mean go down in jet sizes right? i thought you richen (go up in jets)them as lower altitudes because the air is thicker so its getting more air, so you need a bigger jet to compensate for the extra air?
 
Altitude, Humidy, and Air Temperature

Once the jetting is set and the bike is running good, there are many factors that will change the performane of the engine. Altitude, air temperature, and humidity are big factors that will affect how an engine will run. Air density increases as air gets colder. This means that there are more oxygen molecules in the same space when the air is cold. When the temperature drops, the engine will run leaner and more fuel will have to be added to compensate. When the air temperature gets warmer, the engine will run richer and less fuel will be needed. An engine that is jetted at 32deg Fahrenheit may run poorly when the temperature reaches 90deg Fahrenheit.

Altitude affects jetting since there are less air molecules as altitude increases. A bike that runs good at sea level will run rich at 10,000 ft due to the thinner air.

Humidity is how much moister is in the air. As humidity increases, jetting will be richer. A bike that runs fins in the mornings dry air may run rich as the day goes on and the humidity increases.

The above was found in here.

\/ \/ \/ \/ \/ \/

Mikuni carburetor operation and tuning
 
Altitude, Humidy, and Air Temperature

Once the jetting is set and the bike is running good, there are many factors that will change the performane of the engine. Altitude, air temperature, and humidity are big factors that will affect how an engine will run. Air density increases as air gets colder. This means that there are more oxygen molecules in the same space when the air is cold. When the temperature drops, the engine will run leaner and more fuel will have to be added to compensate. When the air temperature gets warmer, the engine will run richer and less fuel will be needed. An engine that is jetted at 32deg Fahrenheit may run poorly when the temperature reaches 90deg Fahrenheit.

Altitude affects jetting since there are less air molecules as altitude increases. A bike that runs good at sea level will run rich at 10,000 ft due to the thinner air.

Humidity is how much moister is in the air. As humidity increases, jetting will be richer. A bike that runs fins in the mornings dry air may run rich as the day goes on and the humidity increases.

The above was found in here.

Mikuni carburetor operation and tuning

oh, i thought the lower altitude means richer...well so i would use a lower main jet then most people then? my altitude is 250 feet above sea level...
 
Actually, low elevation generally means you need LEANER jets. Richen as you go up.

LEAN your jets if: warmer weather, lower altitude, less premix oil, larger displacement, more air flow, more humidity.

RICHEN your jets if: colder weather, higher altitude, more premix oil, smaller displacement, less restrictive air filter.

There is some confusion here. I was taught the other way.

The higher the elevation the less fuel required.

Anyway this article should clear it up.

http://www.blasterforum.com/engine-13/effects-elevation-air-pressure-how-jet-accordingly-39872/
 
Altitude, Humidy, and Air Temperature

Once the jetting is set and the bike is running good, there are many factors that will change the performane of the engine. Altitude, air temperature, and humidity are big factors that will affect how an engine will run. Air density increases as air gets colder. This means that there are more oxygen molecules in the same space when the air is cold. When the temperature drops, the engine will run leaner and more fuel will have to be added to compensate. When the air temperature gets warmer, the engine will run richer and less fuel will be needed. An engine that is jetted at 32deg Fahrenheit may run poorly when the temperature reaches 90deg Fahrenheit.

Altitude affects jetting since there are less air molecules as altitude increases. A bike that runs good at sea level will run rich at 10,000 ft due to the thinner air.

Humidity is how much moister is in the air. As humidity increases, jetting will be richer. A bike that runs fins in the mornings dry air may run rich as the day goes on and the humidity increases.

The above was found in here.

\/ \/ \/ \/ \/ \/

Mikuni carburetor operation and tuning

<BLUSH>
You are both right, I am wrong, sorry guys.
I haven't jetted for altitude lately (80-800 feet here) and got it wrong.
That is why I hang around here, you guys keep a fella sharp!
 
<BLUSH>
You are both right, I am wrong, sorry guys.
I haven't jetted for altitude lately (80-800 feet here) and got it wrong.
That is why I hang around here, you guys keep a fella sharp!

Certianly got me thinking, I read the post, said to my self, yup, then went about my business.

But something was making me uneasy, and for about 30mins I tossed things around in my head, and then the penny dropped.

So back to the laptop, Googled a few things to satisfy that I was correct, then posted the article.

Good things come from simple mistakes, I found out a few new things to stack in my quickly diminishing brain space!
 
for some reason its not idleing at all now unless i keep throttleing it, i have 300 main in with my mods in my sig, elevation 250 feet above see level, the plug was previously fowled and i tryed to clean it and reuse it, could that cause it not to idle? should i put in a new plug and try it? oh and the plug i have in now was fowled from having in a 310 main jet before