07-21-2008, 08:37 PM #1
Stock Carb Jetting on Lowell Ported 1390
Wondering what you guys are using for jetting on stock carbs on a Lowell Ported 1390. Single pipe, Advent Yam 94, opened D plate, V-Force reeds, free flow tube, prok F/A's.
Any input would be appreciated.
Currently I have:
2.0 N&S Black springs
07-22-2008, 07:50 AM #2
Spud, I don't know if it helps any but I have a GK 1390, stock 1300 reeds, free flow tube, Riva flame arrestors w/outerwears, opened D plate, stock CDI, stock carbs.
115 Pilot @ 1.25 turns
145 Main @ 1 turn
1.5 N&S with dull silver springs.. 100 restrictor with the others drilled.
It's a little rich for sure but I'm leaving it that way because we do quite a bit of cold weather riding and I'm tired of tuning carbs.. ..
07-22-2008, 08:57 AM #3
A Lowell motor will run hotter than an equivalent Group K motor, so I would think you will need more jetting than a Group K motor
so take the Group K jetting and go larger
It seems everytime I give a lowell motor more fuel it makes more HP
You might further lower the pop-off - up the N/S to 2.3 or 2.5 (though I realize going from a 2 to 2.3 doesn't make much difference) I think as a general rule we all tend to run the pop-off too high
I am guessing on the jetting but you might try 117.5 / 150
Here is the jetting on my Lowell 1530 with blackjacks
80 gram spring
Last edited by philip_gpr; 07-22-2008 at 09:00 AM.
07-22-2008, 02:06 PM #4
Jim, you know I have a 1300 with stock carbs and Lowell porting. Not sure if this will help, but this is what I run:
Been running this for 4 years and all is well.
07-22-2008, 02:53 PM #5
07-22-2008, 07:22 PM #6
Thanks for the input. Interesting. These things sure are thirsty.
Dave - I too have the ported 1300 with advent and V-Force 3's it runs really good with 115 2.0 N&S @ 135 mains low screws 1 turn, highs 1 1/2 turns
This 1390 is a lot thirstier.
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