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 Post subject: jetting general question / finding
PostPosted: Tue Jul 31, 2018 7:48 am 
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Posts: 31
Hello experts,

after a lot of trying and also reading hundrets of post About the jetting I want to tell you what I think what I have found out:
In many posts it sounds as if you change the Pilot air Jet ( usually between 1.1 and 1.4 ) this would influence the idle circuit/ mixture made by the Pilot Jet ( usually 22.5 -27 ).
This is not correct ( I believe ). The air for the Pilot fuel Jet Comes from a fixed bore , see drawing of official Manual. The Pilot Air Jet in the drawing is the one behind the pressed ball ? This should be the fixed one, which is different for the front and rear Banks and Feeds the Emulsion tube for the main mixture.
SO IF this is correct so far, … what is the srewable Pilot air Jet for ? I wanted to know and made a test -> blowing cigarette smoke with a straw through the 1.4 air Jets of mine….
I couldn't believe what I saw ! Try this by yourself and tell us your Outcome ;-)

The smoke came back from the top of the slider, NOT from the Emulsion tube, and not from the idle Exit bore.

Funny...
Anyway changing it makes the response at around 1/8-1/4 throttle Opening more rich ( Rough ) or lean ( hesitating ), but the same effect Comes from changing the Pilot fuel Jet.
So this might be the reason, why it is so difficult to adjust the jetting precisely in a small range of throttle, because the Impact of the components is unclear somehow…


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 Post subject: Re: jetting general question / finding
PostPosted: Tue Jul 31, 2018 11:42 am 
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Joined: Thu Mar 09, 2006 12:54 pm
Posts: 253
Location: Germany
The culprit in your observation is that you assume all passages open and not clogged.

My observation was that changing idle air jets perfectly influenced the range around 1/8 throttle opening and the engine was reacting the same way as it would to an idle air screw.
The effect is similar but not equal to changing the idle jet. Have a look at what an air correction jet does in a venturi.
(it prevents going rich at higher flow as fuel and air flow are different - one is linear and one a square function of pressure)
I wouldn't rate that as "unclear" as this is how every carb works.

BTW: I admit I never checked where the idle air was exactly coming from.

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Martin


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 Post subject: Re: jetting general question / finding
PostPosted: Tue Jul 31, 2018 2:42 pm 
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Joined: Thu Nov 17, 2005 11:12 am
Posts: 371
Location: Leicester, NC
The pilot air jet (located offset from center at 4 o'clock) bleeds air to the pilot jet (no surprise there). It doesn't connect to the emulsion tube or main air jet.
The main air jet resides behind the pressed in BB at the center of the bore at 6 o'clock. This circuit is cross drilled to connect to the atmospheric pressure fed (as opposed to venturi affected air) float bowl vent. This is the source for air that is metered into the needle jet / emulsion tube / nozzle (otherwise known as the part of a thousand names) as the needle rises and exposes more of the bleed hole area in the barrel of the nozzle.

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 Post subject: Re: jetting general question / finding
PostPosted: Tue Jul 31, 2018 10:59 pm 
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Know it all. Just a reminder. How my shifting has changed.
https://m.youtube.com/watch?v=YsB2Yqp1a8A


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 Post subject: Re: jetting general question / finding
PostPosted: Wed Aug 01, 2018 1:00 pm 
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Posts: 31
I have done the smoke test again, and you are right! Smoke exits scharp from the pilot mixture exits and returns then downwards from the slider . Blowing the venting hose will smoke the venturi by the needle port.
I should wear glasses next time....
Thanks for your explanations Martin and Rick !


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 Post subject: Re: jetting general question / finding
PostPosted: Wed Aug 01, 2018 2:13 pm 
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that little vid kinda made my day, thanks


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 Post subject: Re: jetting general question / finding
PostPosted: Wed Aug 01, 2018 3:29 pm 
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Joined: Wed Sep 15, 2010 4:48 pm
Posts: 539
Location: Lecicestershire
pstamper wrote:
Know it all. Just a reminder. How my shifting has changed.
https://m.youtube.com/watch?v=YsB2Yqp1a8A


Might want to buy yourself a good set of gloves :grin: :grin:


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 Post subject: Re: jetting general question / finding
PostPosted: Wed Aug 01, 2018 5:41 pm 
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Thanks for noticing. I am a squid. Seriously I went over to the toll road and it was 100 outside. Was doing a carb comparison test on Ricks carbs. At that speed I would of been hamburger. I was going to use my phone to time how long it got to full revs from different throttle positions and gloves would not allow it. Bad idea and I agree 110%. My track gloves are the Taichi GP ones. Excellent glove. Better than top of the line Alpinestars. The best Alpinestar glove, most expensive, have very little hand protection. I bought them and sent them back for the Taichi.

Here is the track bike. Sure does not rev like the street bike.
https://m.youtube.com/watch?v=S9U2JR5yltc


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 Post subject: Re: jetting general question / finding
PostPosted: Wed Aug 01, 2018 6:41 pm 
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Enjoyed both the vids immensley! If an RD box could handle it, you'd relish a quickshifter, I love pinging thru the gears on WOT on my (main) road bike.


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 Post subject: Re: jetting general question / finding
PostPosted: Wed Aug 01, 2018 8:57 pm 
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I was able to ride a BMW RR at last years Kern event and after two laps I was wondering why I ride the RZ at the track. Wheelie every gear on upshifts and they told me just be off throttle downshifting. 170 on the back straight. Knee down on second lap. What a wonderful bike. They were demoing the HP4 race and there were two Suter 500s there for weekend. They should of let the 4 bikes out for entertainment at lunch.


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 Post subject: Re: jetting general question / finding
PostPosted: Thu Aug 02, 2018 9:58 am 
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pstamper wrote:
I was able to ride a BMW RR at last years Kern event and after two laps I was wondering why I ride the RZ at the track. Wheelie every gear on upshifts and they told me just be off throttle downshifting. 170 on the back straight. Knee down on second lap. What a wonderful bike. They were demoing the HP4 race and there were two Suter 500s there for weekend. They should of let the 4 bikes out for entertainment at lunch.


I bought the "R", cant cope with a sportsbike riding position nowadays, its super comfy , "only" makes 165BHP vs the RRs near 200 but its on shorter gearing and a more torquey lump, it just flys even at 3,000RPM in 6th and fook does it wheelie...I also has other track electronics like a transponder to get your lap times, pit lane limiter etc etc..which im aiming to try out in a few weeks..im also liking the cruise control a lot.

[url]Image

Sorry to take the thread off topic...


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 Post subject: Re: jetting general question / finding
PostPosted: Thu Aug 02, 2018 11:03 pm 
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Biaaatttccchhh. Dang electronics. That RR was sooooo much fun. His next event is Virginia International raceway South track. The BMW M cars will be there along with the BMW engineers. I so need to take a few weeks off and do Barber again on way back home. The RZ is a blast but at my age power sometimes trumps skill. Seriously NATE has pulled me aside and said he appreciates me bringing the RZ to his events. Number one it never, never breaks down and second that it passesse the RR,s, Apillias, and Ducatis.

This was two years ago
https://www.youtube.com/watch?v=j-v0A30Ifsw


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 Post subject: Re: jetting general question / finding
PostPosted: Sat Aug 04, 2018 9:46 am 
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That was when you were still running the modified stock air box. My carb mods with the TriPods are on it now. I assume it revs better (same as the street bike)?


pstamper wrote:
Thanks for noticing. I am a squid. Seriously I went over to the toll road and it was 100 outside. Was doing a carb comparison test on Ricks carbs. At that speed I would of been hamburger. I was going to use my phone to time how long it got to full revs from different throttle positions and gloves would not allow it. Bad idea and I agree 110%. My track gloves are the Taichi GP ones. Excellent glove. Better than top of the line Alpinestars. The best Alpinestar glove, most expensive, have very little hand protection. I bought them and sent them back for the Taichi.

Here is the track bike. Sure does not rev like the street bike.
https://m.youtube.com/watch?v=S9U2JR5yltc

_________________
If I disagree with everyone, that doesn't make me right. If I take the side of only one, it doesn't end the fight. If my position's strong enough from exposure to the light, you may see things my way when we share the same highway.


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 Post subject: Re: jetting general question / finding
PostPosted: Sun Aug 05, 2018 12:28 am 
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Yes sir it does but peak HP is 9,500 rpm. So as you have taught me use the tourgue. See you in September. VIR and Barber on way back.


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