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What does STD and STK jetting mean?

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OP, jetting charts are good to get you in the ballpark but if you want it 'perfect', 

you'll still have to fine tune to your specific conditions. (engine's state of tune, mods) and to match daily ambiant temps, humidity, elevation.

Edited by mlatour
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"Stock, standard, OEM", 

commonly means the jetting specs that the manufacturer initially set the bike to when new,

usually meant as a baseline for 68°F , 0 ft (sea level) elevation and average humidity.

Any change in these variables means you have to compensate leaner or richer.

 

A worn top end, worn reeds, leaky crank seals, air leaks, wrong float/fuel level etc.

can all alter how the engine runs (lean/rich), so making sure everything else is perfect

BEFORE you fine tune the jetting is a priority.

Edited by mlatour
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Yeah I need to figure it out but I would need to learn what the humidity, And temperatures affect the jetting.

I ordered a 7 slide because it is supposed to change the curve of the throttle to what the bigger pipe recommends, and also I'm richening the pilot, and leaning out the main.

350 main, 50 pilot, 6DHY53-76 needle 3rd pos, 1.25 turns, 7 throttle slide.

Those are my base jetting specs. It has a lean bog when you cut the throttle, and it is always slightly oil covered after a long rip. So it seems about right to me. I also ordered the two gears and the shift fork for first gear, that was my problem on my other post. :)

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Higher ambiant temperature, high humidity, higher elevation, all make the engine run rich requiring leaner settings.

 

 

Edited by mlatour
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1 hour ago, mlatour said:

Higher ambiant temperature, high humidity, higher elevation, all make the engine run rich requiring leaner settings.

 

 

Im stealing this and adding it to my jetting memo :thumbsup::)

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7 hours ago, mlatour said:

Higher ambiant temperature, high humidity, higher elevation, all make the engine run rich requiring leaner settings.

 

 

What happens when you have Higher ambiant temperature, low humidity, higher elevation?  Would you still go leaner?

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Yes in your example, leaner.

 

It's all relative to air density, the cooler the air and/or the closer you are to sea level, the denser the air is.

At higher temps and/or at higher elevation, air is less dense requiring leaner settings.

 

 

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13 hours ago, mlatour said:

"Stock, standard, OEM ", 

commonly means the jetting specs that the manufacturer initially set the bike to when new,

usually meant as a baseline for 68°F , 0 ft (sea level) elevation and average humidity.

Any change in these variables means you have to compensate leaner or richer.

 

A worn top end, worn reeds, leaky crank seals, air leaks, wrong float/fuel level etc.

can all alter how the engine runs (lean/rich), so making sure everything else is perfect

BEFORE you fine tune the jetting is a priority.

Yes I ordered new bearings, seals, I took my reeds apart and cleaned them and they're airtight, and my piston and rings are good. So now I'm looking yo get it running for maximum throttle response and then I'll adjust it to the weather as it changes

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Don't judge throttle response on how well it revs up in neutral / on the stand.

Fine tune it in actual riding conditions with the engine pulling under load.

Edited by mlatour

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