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230 jetting

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Altitude=5,500 feet.

Airbox and exhaust mod done

PJ: Moved up to 38

MJ: Came with 128, currently running 130.

Fuel Screw: 1.5 turns

CARB is a TK POS!

Bottom end is fine. No bog from idle. When in 4 and 5 gear, in full throttle the big bogs down from mid to full.

Two questions: Should I go up to a 132 or 135.

Where do I find a TK jet? I called my dealer and they had not idea. All they could get is a 125.

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The stock main jet was a 125.

At high altitude with the snorkel removed and the exhaust baffle out, run a 122.5.

The 38 pilot is an actual TK part with a Yamaha part number. With a 38 pilot, which is a good choice, only turn out the fuel screw 1.0 turns.

The main will take mikuni main jets, strangely enough. Even the 125 will run ok with the current colder weather.

The sea level bikes take a 130 main.

My son's '08 runs terrific at the same altitude, and the combo has been dyno-proven to be jetted correctly.

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is the 122.5 you are running a TK jet?

What is your elevation?

I wondered if I was running rich. It is hard to tell on the account that they come so lean from the factory.

Thanks for your response

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Did you use the big head mikuni or the small ones? What did you do with the round plastice pieace that the jet holds in place?

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I think it is a small head. I'd have to take it apart to refresh my memory, and it's cold out. My elevation is the same as yours, and the bike runs great at 4,000 or 9,000 feet.

The white plastic jet splash guard won't stay on, so it's off now. You can't tell.

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Am I missing something? Ophir asked whether to go to a 132 or 135 main, which would increase the fuel to match the increase in air from the airbox and pipe mods. Yet, Leardriver recommends going to a 122.5 which seems to be going in the wrong direction. I live at 7000 feet, have an FMF pipe, airbox cutout and a uniflow filter. Should I really be in the 122.5 main jet range?

Also, why no big adjustment to the pilot?

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The engine is an air pump. When you increase the efficiency of the pump through better intake and exhaust, etc, it pulls more fuel through the same jet. Big bore kits often require leaner jetting due to increased carb vacuum, also called signal.

So, the stock main jet is a 125. After uncorking, a 130 runs better AT SEA LEVEL! Since you reduce the main jet one size for every 2,000 feet above sea level, a 122.5, which is three sizes leaner, is about right for 6,000 feet. Clear as mud?

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