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Carburation Question

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artbone:
To make the pilot system leaner do you increase or decrease the size of the pilot air jet (the one in the top of the carb?) Stock is 130 so to lean it out I would go to 135 I think. If anyone knows for sure, please enlighten me.

Prophet Of Doom:
Not sure why you would want to make an overly lean bike leaner, but bigger numbers on the pilot air jet passes more air and so makes it leaner.
Euro spec for the 11U and 16R models (1982) is F120/R120 and I found that significantly better overall than the 130 and 135 that I've also tried.


artbone:
As to why I want it leaner, I live at 6500 Ft and regularly ride up to 9500 Ft. The bike pulls strong and doesnít have a flat spot or the famous Vision Stumble but I still think it feels a little rich. Iím going to try one or two sizes at the time until it feel right to me.

Prophet Of Doom:
Sorry, I'd forgotten that. Presumably it's hotter in mexico than the rest of the world also - that will have a similar effect to increased altitude.   Hot air is less dense and has less oxygen.
Pilot air will only adjust up to about 1/3 throttle.  The main air jet is hard to swap out, but perhaps think about reducing the main fuel jets as well to get leaner across the board. 


artbone:
I went down to 122.5 on the main jets and 140 on the pilot air jet. I think the bike runs better than it ever has. I might order a couple sized smaller, maybe 120 and 117.5 but I'll probably leave it alone. I forget to mention that Iíve got MAC pipes on it. It has no hesitation, no Vision Stumble, just pulls like a freight train to 10K.

It does have one other problem thatís just turned up in the last couple of weeks. Sometimes, when the bike has been ridden long enough to get completely warm, then let sit for 30 or 45 minutes, it will crank on one cylinder and act as if one spark plug is disconnected. It will run like that a few minutes then suddenly start running on two cylinders. I canít determine if itís fuel related or electrical. It did it today as I was riding out in the country and I putted along until I got to a place I could pull well off the road. I lifted the seat and pulled each of the fuses out. They all looked good so I put them back and tried it again and it fired right up and ran perfect the rest of the way home.

I had replaced the diaphragm in the fuel pump and looked at the diaphragm in the petcock and it looked fine. I replace both the fuel and the return lines. As I said, when itís running itís running the best itís ever ran.

I have intermediate problems.

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