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Adjusting carbs for changes in temp/humidity/elevation

Started by Darkstar, April 17, 2017, 06:17:32 AM

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Darkstar

After rejetting, I started paying more attention to how the engine was running across different seasons. I've found that the air/fuel-pilot mixture screw is an easy way to tune while out on the road. It's a but of a guessing game, but when I start to lose a but of power, or it gallops a bit, whatever, I stop and consider what changed in the weather. For example, the temp and humidity climbed while I was out on a ride recently and I felt the performance drop down a bit. Assuming the mix had become rich because there's less room for oxygen in this weather, I pulled over and was able to get some power back by leaning it out. Anyone else doing this?
2007F with 22k NY/NJ miles. Stock exhaust/airbox. Rejet to 20/60/132/one o-ring/1.25 turns out, +2 mojo

Watcher

Ideally you just set your carbs for the average and let it lean and fatten as weather permits (which shouldn't ever be much).
For the street I don't think it's really a necessary practice.  A lot of fiddling for a minor change.

On the track, however, could make or break a podium finish.
"The point of a journey is not to arrive..."

-Neil Peart

Darkstar

Quote from: Watcher on April 17, 2017, 11:13:13 AM
set your carbs for the average

Have others been able to do this with temp variance as wide as 20-90F?
2007F with 22k NY/NJ miles. Stock exhaust/airbox. Rejet to 20/60/132/one o-ring/1.25 turns out, +2 mojo

Watcher

Quote from: Darkstar on April 17, 2017, 12:07:12 PM
Quote from: Watcher on April 17, 2017, 11:13:13 AM
set your carbs for the average

Have others been able to do this with temp variance as wide as 20-90F?

I mean, living in the desert I'm currently getting highs in the 90s and lows in the 60s, I'm sure very few parts of the world get similar variance daily.
But my Duc seems to work fine both at midnight and at mid-day...

When I lived in Chicago and had my GSs I'd ride in the winter on carbs I set in the summer.  It gets in the 90s in summer and 20s in winter.
Maybe not set for optimal performance but they ran fine enough for me, not boggy or otherwise problematic in winter.
"The point of a journey is not to arrive..."

-Neil Peart

Darkstar

Well, I may have something else happening then. I set my carbs to run at 30F, ran great until air temp hit 50F and then it stumbled slightly. So I adjusted the mixture screw and it ran great. A month goes by and air temp hit 85F, and then it stumbled. I kept riding because I was on a group ride, it stumbled harder until it felt like a gallup, then I lost a lot of power and I actually had to pull over. But again, I adjusted the mixture screws again, and it ran great the whole day.
2007F with 22k NY/NJ miles. Stock exhaust/airbox. Rejet to 20/60/132/one o-ring/1.25 turns out, +2 mojo

Watcher

Well, now that it's set for your summer days might want to just wait and see how it handles come colder weather.
"The point of a journey is not to arrive..."

-Neil Peart

Darkstar

Quote from: Watcher on April 18, 2017, 10:44:13 AM
Well, now that it's set for your summer days might want to just wait and see how it handles come colder weather.

if it lasts that long, with the oil im spewing. thanks though. this bike might be up for grabs soon
2007F with 22k NY/NJ miles. Stock exhaust/airbox. Rejet to 20/60/132/one o-ring/1.25 turns out, +2 mojo

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