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air pilot jets

Posted: Tue Mar 21, 2017 2:16 pm
by jimcox145
I am rebuilding both carbs 97 1400 intruder. someone tinkered with it and had main jets reversed. so I checked all jets and found the rear air pilot jet is supposed to be 1.55 and it is in fact 1.65. with that have adverse effect ? all others are correct stock # specified.

Re: air pilot jets

Posted: Wed Mar 22, 2017 6:27 am
by old time rider
Never had the carbs off my 1400 in 45,000 but did do lots of jet changes in ten years of drag racing.Leaner is meaner you learn fast at strip.Lots think the more gas you throw in the better.Intake and out let need to be more flow to need more fuel.It will help them sometimes on starting and other side of too lean is a burnt piston :eek: .As far as hurting it I don't think so but lots better wrenchs than me on this board by a long shot. Good luck. :cheers:

Re: air pilot jets

Posted: Wed Mar 22, 2017 9:09 am
by jimcox145
I bought bike used a month ago and knew from the start that there were issues. Everything is stock with the exception of that rear air pilot jet. I am keeping it all stock till next winter. I am adjusting floats today and reassembling bike this afternoon. Fingers crossed.

Re: air pilot jets

Posted: Wed Mar 22, 2017 9:17 am
by navigator
You know you will need a re-sync right?

Re: air pilot jets

Posted: Wed Mar 22, 2017 11:03 am
by WintrSol
The rear carb is tuned richer than the front, probably because the rear will run hotter. Increasing the size of that air jet will make it a bit leaner in the throttle position between idle and where the needle jet takes control, except during hard decel, when it is cut off. I don't know why you would want it this way, as many complain about pops in the exhaust in this range, and leaning it should make it pop more. Unless it was tuned with an exhaust sensor on a dyno, I wonder why someone installed it?

Re: air pilot jets

Posted: Mon Sep 04, 2017 9:26 am
by Fred
The Bs 36 Mikuni has 2 air jets, one of them is closed off by the coasting valves to richen the mixture to stop popping at overrun.
1.55 to 1.65 on one jet is nothing. These are agricultural fuel guzzling motors of 700cc per cylinder, competative economy was not in the eye of the designer.