Re:Hey Doc...The jetting saga continues!
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TOPIC: Re:Hey Doc...The jetting saga continues!
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Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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Looking back through past posts I know you played around alot with 170/167.5 mains and 35/37.5 pilots. An old post also suggested (by you) that I change my 35 to a 37.5 in Oct.- Nov. as the cold is giving me spit and sputter. My question...What made you suggest the pilot vs. the main? Could you change either/or? |
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Re:Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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 can't remember 
You'll find as the temp drops in the fall the bike will exhibit the spitting and sputtering. The air is denser as it gets colder and so if you have your bike set up for the summer months, it tends to run leaner as it gets colder. If you have it on the leaner side then it will be really obvious as it gets colder.
Generally, you can offset the leaner condition by turning your PMS out a bit. Obviously if you're already maxed out on the PMS you'll have to change out the pilot. However, I'd not recommend re-jetting ( main or pilot) for the few days you're going to be riding at these temps. Just keep the choke out a bit longer until it's fully warm .... and don't hammer it while it's still cold.
Doc |
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Re:Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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I need to do something because it's to the point where I can't ride it. I even added two washers under the spacer on my needle and its still not enough to eliminate the pop and spit on acceleration.
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Re:Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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How's it jetted now?
Doc
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vegasdave (User)
Platinum Boarder
Posts: 1158
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Re:Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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Aren`t you backwards on that Doc  Hotter temps leaner,Colder temps richer  |
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If Your Not Moving Forwards,Your Moving Backwards
Live To Ride,Ride To Live 06 Road Star Candy Red
SMOKIN!!!!
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Re:Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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Thanks for noticing but ..... nope .... got it right this time. 
Density is inversly proportional to temperature (Boyle's Law). At room temp (25 C) the desity of air is 1.184 kg/m3 vs at the freezing point (O C) where it is 1.293.
Thus when you look at the air/fuel ratio ..... if you have your carb set up for an A/F ratio of 14 at room temperature, as the density of air increases (lower temp), the 'A' part of the formuala gets larger and so the A/F ratio value gets larger = leaner carb.
Doc |
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Re:Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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Cool  Didn't understand a word you said  In simple terms I thought the more air you sucked in (Dense) (The air. Not me  ) ) the more fuel you sucked in too? |
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Re:Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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Musky wrote:
Cool Didn't understand a word you said In simple terms I thought the more air you sucked in (Dense) (The air. Not me) ) the more fuel you sucked in too?
As it gets colder the fuel also gets denser but no, the fuel is metered by the jet so it does not matter how cold it gets.
Hmmmm .... I guess if we wanted to get picky .... as it gets colder jets shrink and the hole gets smaller so less fuel available.
Head hurts .... have to get some coffee.
Doc
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Re:Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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DocShadow wrote:
How's it jetted now?
Doc
1600, 170 on 4th clip,(spacer under, washer over), #35 pilot, pms 3 1/2
Thats how I had it all season and it ran great. As it got colder and started sputtering, you suggested this:
For riding in Oct and Nov you may eventually need to go to a 37.5 pilot. Might be a good idea to pick the jet up just in case.
Also try 2 silver washers under the spacer before changing out the pilot. You'll need to re-adjust the PMS. That may be enought to richen the circuit out without compromising your mileage to much.
I tried the 2 washers and had very little change. My PMS is all the way out and I still can't eliminate backfire while revving at idol and fully choked.
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Re:Hey Doc...The jetting saga continues! 4 Years, 6 Months ago
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Usually you can turn the PMS out to help richen it for these colder months but as you've already noticed you are so far out on the PMS that it doesn't help. That's why you need to go to the 37.5.
But .... the bike must be fully warmed at this time of year. If you try to be aggressive while it's still cold it will buck back at you, especially if you're on the choke. This begs the question ... do you really want to re-jet for the limited amount of riding you're going to get now?
No air leaks and the float is to spec ..... right? 
Doc |
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