 Quick Jetting Question
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Joined: Jan 2005
Posts: 18,825
"Lighten up, Francis."
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OP
"Lighten up, Francis."
Joined: Jan 2005
Posts: 18,825 |
Over in Misc Tech this can be seen in the 2009 Fuel Injection thread: Quote:
i want the efi, so that i don't have to mess with anything. i'm planning some trips into the mountains, and i live at sea level now. i don't want to have to worry about tinkering with my fuel mixtures as i climb in elevation, i'd rather just have a sensor and chip do all of that for me.
Hmmm. Got me thinking. I live at 4000 feet and just spent a few days at sea level. The bike ran great in Seattle. It runs good here in Helena but maybe not quite that good. I didn't touch the carbs at all during the trip (does that make me a bad person? <--rhetorical). Does that mean I'm running too lean at 4000 feet? If I recall correctly I have the following config:
Short TORs
TBS needles, no shims
Bellacorse Thumbscrews (can't remember the turns, possibly 2)
Drilled slide holes
stock springs
K&N Freak-style filters
42 pilots
145 mains
I haven't looked at the sparkplugs lately.
Last edited by FriarJohn; 07/29/2008 2:58 PM.
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Re: Quick Jetting Question
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Joined: May 2007
Posts: 6,432 Likes: 1
Worn Saddle
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Worn Saddle
Joined: May 2007
Posts: 6,432 Likes: 1 |
The opposite would be true, you may be running much leaner at sea level with the much denser air mass. If anything, your A/F ratio would go richer as you climb in altitude. Have you tried the stock needles lately in Helena?
A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)
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Re: Quick Jetting Question
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Joined: Jan 2005
Posts: 18,825
"Lighten up, Francis."
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OP
"Lighten up, Francis."
Joined: Jan 2005
Posts: 18,825 |
I haven't tried anything lately. I've been running the TBS needles since Spring '06 (about 16.8k miles).
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Re: Quick Jetting Question
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Joined: Nov 2006
Posts: 110
Adjunct
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Adjunct
Joined: Nov 2006
Posts: 110 |
We're at about the same altitude. I took my 06 TBA to Edmonton to have dynoed. I want to sort the results and get them to Staffo for his chart, but this is the quick story.
I went with 155 mains, TBS needles, and 45 pilots. On the first run it was very rich across the whole range. So we changed out the TBS needles with single shimmed stocks,and reduced the mains down to 152. On the second run it was still rich midrange, so we took out the shim to run straight stock needles. This gave a good dyno run.
As a side note, I'm really surprised at the difference in milage that the stock needles are from the TBS cousins. With TBS needles I average 170 to 180 km to reserve. With the stock needles, and it doesn't seem to matter whether there is a shim or not, I average 220 to 235 to reserve.
Steve
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Re: Quick Jetting Question
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Joined: Apr 2007
Posts: 286
Adjunct
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Adjunct
Joined: Apr 2007
Posts: 286 |
Interesting, seems like the folks who benefit most from the TBS (or Thruxton) needles have left the stock #42 pilot jet in place. Maybe the TBS or Thrux needles make up for the smaller pilot at most throttle settings, but if you have #45 pilots, you end up too rich across the board. I never bothered to change the pilot jet, just the main and the needle. Hmm... might have to do some more tinkering with the carbs.
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Re: Quick Jetting Question
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Joined: Dec 2006
Posts: 2,150
Oil Expert
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Oil Expert
Joined: Dec 2006
Posts: 2,150 |
Hey Steve, did you say what type of air cleaners and pipes you had?  Just interested. I'm sort of assuming you have Long Tors and K&N pods. Is that right?
Staintune Pipes, K&N Pods, 45 pilots, TBS needles and 145 mains.
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Re: Quick Jetting Question
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Joined: Jan 2005
Posts: 6,308 Likes: 4
Worn Saddle
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Worn Saddle
Joined: Jan 2005
Posts: 6,308 Likes: 4 |
Quote:
Interesting, seems like the folks who benefit most from the TBS (or Thruxton) needles have left the stock #42 pilot jet in place. Maybe the TBS or Thrux needles make up for the smaller pilot at most throttle settings, but if you have #45 pilots, you end up too rich across the board. I never bothered to change the pilot jet, just the main and the needle. Hmm... might have to do some more tinkering with the carbs.
Give the man a cigar!!
A word to the wise is not necessary. It is the stupid ones who need the advice.
Pat
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Re: Quick Jetting Question
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Joined: Jan 2005
Posts: 18,825
"Lighten up, Francis."
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OP
"Lighten up, Francis."
Joined: Jan 2005
Posts: 18,825 |
That tracks. IIRC, I dropped from 45 pilots back down to 42s when I installed the TBS needles.
Should I try the stock needles with a couple shims each? I'm curious about what Steve said about his mileage.
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Re: Quick Jetting Question
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Joined: Nov 2006
Posts: 110
Adjunct
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Adjunct
Joined: Nov 2006
Posts: 110 |
I had the TORS but didn't like the sound. The dyno was done with Thunderbike pipes and K&N pods. Thunderbike gave me the note that I was after and I can still slip in and out of the neighbourhood at odd hours.
Steve
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Re: Quick Jetting Question
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Joined: Apr 2007
Posts: 3,063 Likes: 8
Loquacious
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Loquacious
Joined: Apr 2007
Posts: 3,063 Likes: 8 |
Curious.
I just put 220km without having to switch to reserve. Put 12.5 liters in the tank. I'm running long TORS with AI removed, all snorkels removed, non drilled airbox, 135 mains, TBS with 1 shim, and 42 pilots. My fuel mileage for city driving has gone down though. The one shim was added to help with the mid range lag.
What about your drive sprocket size - 18 tooth for me.
12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
73 Yamaha TX 750
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Re: Quick Jetting Question
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Joined: Apr 2007
Posts: 3,063 Likes: 8
Loquacious
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Loquacious
Joined: Apr 2007
Posts: 3,063 Likes: 8 |
Quote:
Interesting, seems like the folks who benefit most from the TBS (or Thruxton) needles have left the stock #42 pilot jet in place. Maybe the TBS or Thrux needles make up for the smaller pilot at most throttle settings, but if you have #45 pilots, you end up too rich across the board.
+1
What pilots does the Thruxton run stock?? If your observation is right, this might back it up.
12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
73 Yamaha TX 750
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Re: Quick Jetting Question
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Joined: May 2007
Posts: 6,432 Likes: 1
Worn Saddle
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Worn Saddle
Joined: May 2007
Posts: 6,432 Likes: 1 |
Stock Thrux 856 is meant to have 40 pilots.
A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)
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