"Opening" air jet: Why? Clip on needle question

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2002tiil
Posts: 140
Joined: Mon Jun 01, 2015 5:49 pm
Location: Veendam, the Netherlands

"Opening" air jet: Why? Clip on needle question

#1 Post by 2002tiil » Sat Dec 17, 2016 11:58 am

Hi all,

Bought some carbs for parts/ exchange: What in noticed is that the air jet (mounted in cone air inlet) is fully opened. Is there a reason why this is done?
What will be the right height for the clip on the needle of main jet?
Main jet is standard (165).

It's for a bog standard RZ500.

Thanks,

Richard

2002tiil
Posts: 140
Joined: Mon Jun 01, 2015 5:49 pm
Location: Veendam, the Netherlands

Re: "Opening" air jet: Why? Clip on needle question

#2 Post by 2002tiil » Thu Dec 29, 2016 3:04 pm

Okay, needle position in the middle, #3. figured that out.
Only the reason for fully opening the air jet puzzles me.

steveho
Posts: 229
Joined: Thu Aug 20, 2015 4:01 pm
Location: Southampton, England

Re: "Opening" air jet: Why? Clip on needle question

#3 Post by steveho » Thu Dec 29, 2016 3:35 pm

The experience I have with removing the brass covers over the air jets, on other 2-strokes, is to allow better cleaning of the carbs at the emulsion tubes, as a lot of crud can accumulate there. Maybe the reason? :!: :grin:

Blobber
Posts: 186
Joined: Mon Jan 07, 2008 5:34 am
Location: Lancashire, England

Re: "Opening" air jet: Why? Clip on needle question

#4 Post by Blobber » Thu Jan 05, 2017 11:20 am

Hi - if you are saying there is no air jet fitted to the threaded orifice then the equivalent orifice size would be massive may be 3 mm diameter or more. Bearing in mind the standard is #1.1 (I assume this is 1.1mm dia.) this modification will allow way too much air into the pilot circuit. I doubt the bike would run. I have found that pilot air jets bigger than #1.4 tend to cause a bit of leanness just off the throttle. My comments are based on the rest of the carb being jetted standard.
Bikes:
RZV500R FZR1000 forks wheels JL pipes
RD350LC N2

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