BK carb mod, done, now i need a little help

6 replies to this topic

Posted July 10, 2004 - 10:16 PM


i jus did the BK carb mod today. what i wanted some help with was tuning it with this mod. how should i go about it? i did a search and nothing came up so i figured i should ask and i know someone knows more than me. i have the paper printed up on how to do it and all but from what any of you have experienced what was easy when it came to adjusting the screw? also, after all is said and done, what did you end up with jetting? im at sea level and so are most of my riding spots, (glamis, ocotillo, pismo) so if anyone has theres set close to that it would help out too. thanks for all your help.

  • Satch0922

Posted July 11, 2004 - 02:36 AM


Check out Garrett's jetting spreadsheet. It works great.

jetting spreadsheet

  • skthom2320

Posted July 11, 2004 - 09:45 AM


What do you mean by "tuning it?"

All you are doing is limiting the length of the accelerator pump squirt so as not to overly richen just off idle.

You'll want to adjust the pilot jet and fuel screw combo so you get easy starting.

Next you want to RIDE your bike and see how the off idle response is. If it bog's or hesitates, make sure that you have the FS/pilot jet dialed in the best it can be. Then, adjust the AP screw in 1/8 turn increments to get rid of the hesitation/bog. It shouldn't take too long to do this. Just ride around with the little dust cover off and tune after each lap or so. You'll find the sweet spot pretty soon.

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Posted July 11, 2004 - 09:12 PM


Check out Garrett's jetting spreadsheet. It works great.

jetting spreadsheet

ya, i tried but for some reason my computer wont let me view it. another thing was how much of a change in jetting am i going to have to do, if at all? thanks again.

  • Hamish

Posted July 12, 2004 - 02:11 AM


the BK mod doesnt effect the jetting

  • John_Lorenz

Posted July 12, 2004 - 03:28 AM


I agree with Hamish and skthom2320

Here is a link to a write up I did on the GBmod. The actual timing screw should be left alone in most cases. The write up details how to tune the GBmod for best results.
GBmod Explained
Tuning Aka Jetting is a totally different beast. In order to assist you other then arm chair guesses we need to understand a few things:

1: Sea Level elevation you mostly ride in (Example 1000 foot above sea level)

2: Average Temp of the area you ride (Example 80 90 or 102 degrees)

3: Current Jetting
Pilot = 42 or ??
Needle = EKP clip at position 4
Main Jet 168
Air Screw = 1 1/2 turns out

For instance I ride a 2000 426 with the GBmod at 1000 - 1500 foot average temp is 85 degrees I have the 2001 Needle (EJP) So my jetting for "MY" bike is

Pilot = 42
Main = 168
Needle = (EJP) clip @ Position 3
Air Screw = 1 1/2 turns out

Plus we need to understand just a little bit on what you think the bike is doing, aka does it pop on deceleration (Indication of being Lean), do you see black smoke when reving (Indication of being rich)



Posted July 12, 2004 - 11:04 AM


as of right now i have not rode the bike with the mod done. i ride between sea level and about 500 feet. temp is usually around 80-90. it was running good before with a little popping on deceleration. i was going to mess with the jetting a little but then i decided that it be best if i just wait until i do the mod. once i ride it i will have to start messing with it. thanks again for the help.

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