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Re:More tips on Jetting (1 viewing)
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TOPIC: Re:More tips on Jetting

#72
OldGoat (User)
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More tips on Jetting 2007/05/08 06:28 Karma: 0  
Think need to add a new room, maybe titled Tips and Tricks as some members (me one) play alot with there toys modding them, does not fit any catagory in here now. Here is one I found very useful, post or delete or move as you see fit...

Jetting Recommendations
by Denny Zander

Here is a simple set of jetting guidelines that have worked for me. For those considering jet changes, this might help select a starting point.

1 jet size for custom 4 into 2 exhaust

2 jet sizes for 4 into 1 exhaust

1 jet size for K&N filter (single inside airbox)

1 jet size for drilling out the bottom of the airbox

3 jet sizes for individual filters

2 jet sizes for no muffler (open header)

1 pilot jet size for every 3 main jet size increase

Add up all the jet size increases and subtract one. (Remember they go in steps of 2.5 for each jet size)

Under a mismatch condition, like individual filters and stock exhaust or 4 into 1 header with stock filter and air box, subtract an additional 1 jet size.

Check plug color often, sync carbs after each jet change, make sure the floats are set correctly, and seriously consider purchasing a Colour Tune. (See "Colortuning Carburetors" in the Maintenance Section).

Make sure your carbs are in perfect working order before making jet changes.

Example from my '79 XS1100 F:
Stock main jets: 137.5

Stock pilot jets: 42.5

2 sizes for 4:1 exhaust (Jardine)

1 size for single K&N

1 size for drilled air box

4 (main sizes) - 1 = 3 or 137.5 + (2.5 * 3) = 145.0
1 (pilot jet size) or 42.5 + (2.5 * 1) = 45.0

With this jet configuration I get 32-38 mpg on the open road, Smooth idle, very strong exceleration from off idle to 80+ mph, and steady pull past 120 mph. My "F" has 76K mile on it, of which I have put 44K with this jet configuration.
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#75
rb9594 (Admin)
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Re:More tips on Jetting 2007/05/08 20:01 Karma: 0  
Old Goat, good advice once again and since you keep giving good information, i am honoring you by calling the forum title "Old Goats Tips and Tricks". Send me some pictures of you doing some crazy shit on your bike, your picture is going on the front page!

thanks

ryan
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