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Discussion Starter #1 (Edited)
have been messing with my jetting here (stock carbs) in san diego since moving 2 weeks ago from denver. initially had it the way sean at british customs recommended, 140 mains, 42 pilots and 2.5 turns out. the bike screams (for what it is). had the mechanic at british customs look at the plugs and said they were a bit lean, so i went to 145's. noticed that the bike became a touch flat in the top end and felt a little fat, and the plugs didnt look any different than with the 140's, so i went back to the 140's and tweaked the mixture screws for the highest idle and ended up at 2 turns out and the bike seems to run a bit better than when the screws were 2.5 turns out.

just curious what others are running for jets at this altuitude with predators and airbox removed. i also have aftermarket manifolds. i sort of think the mains are sort of small for my set-up but it seems to be what the bike likes. would like to get it on a dyno and see what the a/f ratio is...
 

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Sounds in line with what others have done - that's pretty much the settings I am going to start with.

Dyno - dyno - dyno - dyno! :D
 

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Discussion Starter #3
the bike ran like doo-doo in denver and i tried everything. different jets, no shims, one shim, two shims and could never get it dialed. i love the increase in power here at sea level. the bike pulls like a SOB up to 115 mphindicated here on the freeway (i back off after that! dont want to lose my license or get thrown in jail!)
 

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Dyno - dyno - dyno - dyno! :D
Or even better.......... A/F Gauge - A/F Gauge - A/F Gauge !! :):)

I recon, for what its worth, that you wont be far away with the 140's
I live at sea level too, and as part of the playing about I did, I ran with no airbox and no filters.
The jetting required for optimum A/F was 145 at that.

Which suggests, with filters, 140's are about there.

V.
 

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you should be real close with the 140s thats what i ran with your same set up.Iwant a a/f gauge to ,but it wont tell you what a/f makes the most power on your bike.They dont all like the same a/f ratios like i use to think.heck my bike makes the best top end hp at 12.8 to one.Some run better at 13.5 to 14.0 I dont think there is anything set in stone as to what works best.You can change pipes ,carbs ,heads and timing and change what jets the bike wants.
 

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http://www.triumphrat.net/twins-technical-talk/96811-06-thrux-dyno-results.html


i posted this a while ago. i had 145's, 42 pilots at 1.5 turns and 1 shim. i was running the emgo's and no airbox. i was running what most would consider slightly lean for max power, especially for aircooled. i think the emgo's are a little freer flowing than the preds, so a step down in jet sizing would put you at 140-142 in the mains. i am at 500-600ft above sea level. take it for what it is. only an a/f on your bike will tell for sure. good luck.
 

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sbpark I'm running the same set up you got now, 140,42,preds, no air box, no AI, K&N pods, 2 turns. Runs good, but smells rich at idle. If the bike sits over night I use the choke just to start and if I leave it parked at work all day, after work don't need the choke it fires right up.Does that sound like your bike?
 

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sbpark where in SD do you live? I lived there for 13 years in PB and Mission Valley. My brother is still over there on North Island (not in the service)
 

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While the a/f guage may not be a perfect method, there is no doubt that it is a fast feedback tool for getting very close indeed to optimum - especially for anyone new to tuning, such as myself. Saves the worry about going so lean you get into danger areas.

I'm not going to go with the permanantly mounted gauge, I figure I like this one better, which has data logging capabilities, so that I can map a/f ratio to the revs. PLus, once I have the Bonnie how I like it, I am pretty much done with it, and I have 2 other bikes that need attention, so this unit works better for me - ah the joys of personal choice!

Once I have it close, off to the dyno to see the overall power / torque results!

LM2 wideband a/f gauge
 

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I had an A/F meter on my former Bandit & it was the most useful addition that I made. I don't know of anyone that installed an A/F meter that regretted it. I may add one to my SM, probably on the crossover tube. We'll see.
 

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While the a/f guage may not be a perfect method, there is no doubt that it is a fast feedback tool for getting very close indeed to optimum - especially for anyone new to tuning, such as myself. Saves the worry about going so lean you get into danger areas.

I'm not going to go with the permanantly mounted gauge, I figure I like this one better, which has data logging capabilities, so that I can map a/f ratio to the revs. PLus, once I have the Bonnie how I like it, I am pretty much done with it, and I have 2 other bikes that need attention, so this unit works better for me - ah the joys of personal choice!

Once I have it close, off to the dyno to see the overall power / torque results!

LM2 wideband a/f gauge
dont get me wrong its a great tool all i am saying it wont replace a dyno if your after max hp.I will get one though
 
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