Author Topic: Summer jetting  (Read 2642 times)


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Summer jetting
« on: August 17, 2016, 03:08:37 PM »
I kind of like tweaking the jetting on my Vision since it's so easy to do.
I live in S. FL where it's hot and humid in the summer and I noticed the bike running slightly rich probably from the air characteristics compared to the Winter when the jetting was much better because of cooler and drier air.
So anyway, I was running 120 MAJ's up top and I picked up some 122.5's and 125's just to have on hand.  I tried the 122'5's on the MAJ and with 3-4 threads showing on the accelerator pump and it's pretty good.  I'm running stock main jets, pilots and pilot screws 3.5 turns out.  Flap is on the airbox and it has a Keyster kit.

I'd say even with the 120's it ran pretty good and the richness was hard to detect under most conditions.  The 122'5's seem a bit better for the time being, but as always I'm always listening to the engine!  :)

BTW- Niche Cycle on Ebay is quick and cheap on the jets.


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Re: Summer jetting
« Reply #1 on: August 30, 2016, 12:43:19 AM »
I think you're on to something here.  I don't have humidity, but I've noticed that my fuel economy goes way down when I'm riding in 90+ days, versus days when the temperatures are in the 70's or 80's.  I think that the temperature compensation for these carbs isn't as good as, say, the carbs on my Ninja.  In temps over 90, I also have to be very careful to keep the bike from stalling at idle, which is never a problem in the cool of the morning.

Hmmm, I with the lack of accurate temperature compensation, I wonder of rejetting might not leave me too lean in the mornings?  I have a feeling that Oregon mornings are a lot cooler than Florida mornings.  This morning was 54, for example.  (The only part of Florida I lived in was Pensacola and Gulf Breeze, and in the summer I woke up wondering if it would ever cool off again.   ;D  For an Oregon boy, that was mighty hot.  Swimming in the Gulf after work was mighty nice, though.)