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Discussion Starter #1
I posted this question in the cafe forum and now i'm really curious what everyone else is using. So if you would post your mods and what you re-jetted to that would be awesome.
Thanks

Ok, so i cut up the air box last night and slapped in a couple of K&N's. Then i retted to 155 mains because that's what the pats jetting calculator told me to do. I've been getting my money's worth of my D tool and have wound up about 3 turns out and i'm getting less power at all RPM's. Especially the higher rpm's. It seems like it doesn't want to go near red-line. I thought about putting a shim under the needle's, but thought i would ask everyone's advice first. Do i need to try some smaller jets?
'06 Thruxton
Epco stainless exhaust
K&N single filters with air box removed.
155 main jets.

TJ
 

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I'm using 140MJ, 42PJ, manual specified float height, and like 1.5 turns out on the idle screw. K&N's, D&D's

Factorypro founder Marc Salvisberg has provided a sweet tuning guide for CV carbs that I have used in the past.Factorypro Give this a look, it is the gospel on CV carb tuning, as far as I'm concerned.
 

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Gads, I can't say if my set-up is Dyno sniffer friendly yet or not
- but -
at this juncture, it's running it's best so far.

NH bellmouth (powder coated a smooooth Black)
K&N air filter
Thruxton needles
D&D cans with Big City Thunder baffles
40 pilots (soon to be changed to 42's)
130 mains (from 118's, waaaay too lean. 122.5's prior, ran better than the 118's)

I had a really bad cold starting problem, thus my having bought the 42 pilots. As soon as I dropped the 130 mains in, my cold starting problem lifted and the bike reached an indicated 115 mph when it was warmed up. My plan is to have it sniffed before I install the bigger pilots, and if I'm running too rich according to an air/fuel reading, I'll drop down from the 130's.... but not by much I imagine.

Frankly, I think every bike is unique.... and you just hafta ask for a baseline to work from, then figure out what works best with YOUR set-up. No two bikes alike.
 

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I'm pretty sure I was at 152.5 mains...45 pilots and 3 shims under the stock needles when I had my stock carbs on. Mods were airbox removal, and specialty spares pipes. The pred's seem to be a little less free flowing than the specialty spares pipes, but didnt affect performance regarding needing a rejet. I think I had the screws turned roughly 2 and 3/4's out.


The mikuni's are totally different regarding jetting.
 

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Frankly, I think every bike is unique.... and you just hafta ask for a baseline to work from, then figure out what works best with YOUR set-up. No two bikes alike.
Especially true with carbureted bikes. Several variables.
Bob
 

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I run two different set up's.The first with CV carbs;152.5 mains,air holes bored out,needle pos 3, air filters with velocity inside them,nology ht coil and wires,and a 17 tooth sprocket''sometimes''.The other CR2 smoothbores 135 mains needle pos 4 with my throttle set to hard to turn.I use standard plugs.
 

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A year or so ago, many with the 865's were running smaller main jets with the airbox removal than most with the 790's. I could never understand why, since I don't have an 865. I believe many were running main jets in the range of 140 to 145 at that time. When I tried 140 main jets in my 790, it ran about like stock. With 150's it really turned on. I could tell no difference between Thrux needles, TBS needles, and stock needles--all were rich (the thrux and TBS were VERY rich--this I learned on the dyno runs with EGA. With 160 main jets, I couldn't tell any difference, so I went to the dyno.

I disagree with the post about doing the mains last. IMHO, the old rules still apply: get the main jets sorted out FIRST, the needles second, and the pilot jets last.

'03 790 with 17 tooth counter sprocket. :-D
Dynoed at 745' elevation:
NH Togas
NARK with K&N's
AI removed
Stock needles (a little rich in mid-range--12 A/F)
158 main jets
42 pilot jets (40 pilots would also work fine)--this was not the case when I had headers without a crossover pipe...I had to use 45 pilot jets with that setup.

50+ mpg. :-D

Larry
 

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A little 60 mile jaunt this evening on the Bonnie..... 6:30 drunk illegals in their pick-up trucks running along-side me in my own freeway lane, a gang-banger bouncing off the white lines & changing lanes at high speed, and a gal paying more attention to her cell phone conversation than to her driving.

My cheap bar-end mirrors with their stamped-out steel brackets having twisted off their post, only to be replaced with my factory mirrors on bars too narrow to see ANYTHING behind me.

- AND -

Main jets not quite as spirited at top-end after the engine warmed up on this ccccold night. The 130's are too fat for my application, think I need to drop to 125's.

Right between on throttle & off throttle, there is a tiny hint of non responsiveness to throttle input when kinda/almost accelerating. Too lean at mid-range, gonna put a shim on my Thruxton needles.

Upon cold starting, still hafta hold my tongue right and choke setting just'..... will put those 42 pilots in when my suspicion is confirmed that my 130's are too rich.

And then there was that Thai gal on my way home who rode her little sister's bike (with no lamps or reflectors) against a red light, causing me to grab a hand-full of brake to avoid from hitting her. Saw all my buddy's sitting at the bar either doing a low-carbohydrate diet of Diet Coke & Rum, whining in their Chablis about being 50 & single, or the married gal who spends more time at the Brewery with the fellas than with her husband and/or daughter. And Chris..... how he ever gets home is beyond me, given the pictures of beer he drinks nightly (hmmm, I don't think I've ever seen him eat).

What the hell, satisfied with what I've concluded about my jetting.... I think I'll go join the guys at the bar, have a greasy burger, and stare at Leah's.... uhh eyes. Stockton, California..... the "All American City". We have more illegals, Hmong, Vietnamese, Norteno's, and brotha's here than ANYWHERE in the United States...... and none of 'em can drive. Stockton, "one of the most dangerous cities to ride, drive, or even walk..."

G'night y'all, think I need a drink (and to increase my "under-insured" insurance).

[ This message was edited by: FattRat on 2006-12-12 08:29 ]
 

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Discussion Starter #13
I can't wait to get my stuff from newbonneville and start trying to get it dialed in. i just talked to the guys at the mid-ohio harley shop and i'm going to get it on their dyno as soon as i get it closer. I'll post results when i do. I suspect that in the end i will be running 140-142 main jets, 45 pilots and a shim under the needle.
 
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