Rejetting after ear shave? - Page 2 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #11 of 12 (permalink) Old 06-08-2019, 11:07 AM
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You may do well with a slight rejet then. I'll tell my tale and eventual final tune:

Rejetted when I did the earshave with 142/42 and 2 needle shims. Ran like that for a year or so, but the bike was pig rich. I could smell gas when I cracked the throttle, hardly needed choke to cold start it. After I did the pickup coil modification, I found that it was really eating up that rich mix, but I wasn't a fan of the smell and (am pretty sure I had some erratic running issues)

I switched back to a stock pilot (38) with 1-size above stock main jet (135, stock is 132) and left my shims in place. With the coil mod and earshave, my bike starts with choke, doesn't smell pig rich, and responds perfectly to all rev ranges, throttle inputs, etc. Pulls strong through the whole rev range, doesn't pop on decel, and idles at a very stable 1100 rpm, hardly even have to fiddle with the idle when seasons change.

Way I reckon is this: stock pilot works at idle, that's limited not by intake/exhaust, but by the valve openings, no need to give it much more fuel there. Once the throttle comes on it's getting the needle lifted, the shims add a bit of additional fuel throughout the middle of the range where my pods let it breathe a bit more, and ultimately at WOT the main jet is giving it all it has, and I wanted just a bit more fuel there since the bigger pods will be providing more air.

Also worth noting that my stock pilots were unusable since they were so clogged, so even if I didn't rejet I still needed to replace the jets.

If you have punched baffles and an earshave, 135/38 or 138/38 might work well for you, and you can experiment with shims without removing the carbs, just gotta take the gas tank off to get the carb hats off. If you want more power in addition to this look up the coil pickup mod, I felt a big difference with that and the rejet.
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Earshave+Rejet (38/135) NGK Iridiums MCCT Conversion Slipstreamer S03 Windshield Custom Extended Backrest Custom Highway Bars MOSFET R/R LED Underglow Volt+USB In-Dash Two-Wire & Blue-Wire Mod Satin Black Engine Paint Dampers Parts - Jets: Main=99101-393(#132 stock)/Pilot=n424-22 Pilot(#38 stock)
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post #12 of 12 (permalink) Old 06-09-2019, 07:58 AM
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ubertalldude I forgot about the coil mod. Interesting that you ended up with 38/135. I've heard that each bike is a little different. Mine HATED shims. Ran at idle and WOT but stumbled at cruise.

Even with the 40 pilots, it's still lean in specific circumstances. I don't need to go through my whole story again, as I have a 6 page thread on finding the right jets. 😉

I just don't understand how two bikes with the same setup could require different jets...but it is what it is.
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'89 Vulcan 750 Bought 4/12/18 @ 17805.9 miles $800
Purchased stock. Wrecked once
22490.0+ miles

Completed modifications:
Removed mufflers, straight pipes out of GB
110/90 Front Tire
Pick-up coil re-gapped to .020"
Compufire 55402 r/r series regulator
USB Outlet + Voltmeter
Repainted Metallic Blue w/ new tank bages
Ear Shave (wo/ coasters) 40/140 NO shims 45MPG
MCCT conversion

Planned modifications:
Custom LED turn signals
Windshield
Highway Pegs
(Possible) ignition advance
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