Mid throttle jump - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 5 (permalink) Old 01-16-2018, 10:38 PM Thread Starter
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Mid throttle jump

The title explains it. I've got experience and bikes. However, the vn750 is a new breed. Just picked it up at the end of the last season. Rode it through fall put it away for winter. I'm doing some customizing on the bike. However, before the next riding season I need to swap out the tires and figure out what's wrong with the engine. I'm pretty sure it's nothing to do with the engine itself, but the carbs. My front cylinder runs fine. However my rear cylinder really only kicks in between a third and half throttle. I checked all my cable tensions everything's fine. The guy I bought the bike from said he dip the carbs and rebuilt them. The carbs both look brand new. I think it may just be bad jetting. Just looking for some advice.
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post #2 of 5 (permalink) Old 01-16-2018, 11:36 PM
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Dirty/clogged pilot jet.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #3 of 5 (permalink) Old 01-17-2018, 08:13 AM
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what Spockster said. even after I chemdipped my carbs and put new jets in I tried chem dipping my pilot jets for a few days to see if I could get the gunk out, no such luck. maybe if I had run some guitar string through there I could have, but once that varnish gets stuck in there it's hard to get out

luckily mains don't get clogged as easily, and jets aren't too expensive should you elect to replace them rather than trying to clean them out

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 #4 of 5 (permalink) Old 01-17-2018, 12:28 PM
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Yup, guitar string is good. I stripped the plastic off a bread bag tie, twisted and poked it, soaked it, rinse, repeat until it opened up. The soak was Castrol Super Clean full strength. Be sure and clear out all the tiny emulsion holes on the jet tube. Can't see those until you take the jet out.

When the rear pilot clogged on mine, it idled on cylinder, was down on power at low rpm, and then the power would explode when the main jet kicked in. Made it wild to turn corners. Had to adjust the idle back down after both carbs were working.

Got an ultrasonic cleaner, so next time I'll put Super Clean in that, or white vinegar. The ultrasonic works great though!

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #5 of 5 (permalink) Old 02-08-2018, 05:44 AM
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+1 on plugged jets. Welding tip cleaner work well for cleaning jets too. If it hasn't been done in the past year, syncing the carbs makes a big difference on these bikes.

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