Thread: Mikuni Jetting
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Old 09-16-2012, 12:54 PM   #2
Kai Ju
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Joined: Jul 2009
Location: So Cal
Oddometer: 1,910
Here is what I'm running on a 77 R100/7 in the VM 38's. Stock (Repro ) mufflers, stock airfilter and airbox.

Description Spec
Main Jet 210
Pilot Jet 25
Needle Jet 166 P-8
Jet Needle 6DH3 middle groove
Slide Cut Away 2
Main Air Jet 0.5
Needle Valve Ass'y 3.3
Idle air screw 1 turn from seated

I started with a 17.5 pilot which was way too lean and a 200 main, which felt too rich. Going to a 190 made it worse while a 210 made it better. So that's what I'm running now.
I compared the stock Bing mainjet to the 200 Mikuni jet by inserting a very shallow taper reamer and the Bing mainjet, a 145 I believe, is actually larger in hole diameter than the 200 Mikuni mainjet.
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