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Discussion Starter · #1 ·
Is there a difference in tuning for performance vs AFR?
I would think that the AFR set properly thru the dyno tune would also represent the best performance.
I read that the best performance AFR was at 12.8:1. Is this a good target ratio?
What would be the results of a dyno tune done in 5th gear vs 4th?

Reason I'm asking is that after my recent dyno tune it went from 108 ft.lbs tq down to 95. WTF! Also lost 1 hp which didn't get me excited but I can't choke down the tq number at a loss of 13 ft. lbs.
The bike runs good but feels like it has been neutered. I told the owner that I wasn't happy and he said to bring it back and they would run it again.
Their target AFR was set at 13.5 which I think is a little lean. He said that he could get more power but it would run hotter. That would mean that he is talking about setting it at a leaner ratio such as 14:1, right?
How did I lose 13 ftlbs of torque? I know that different tuners will give different numbers but this is way off.
 

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First, tuning on a dyno is not always a good thing. All dyno's are good for, I know I will get flamed for this, is giving you an idea of the numbers you are producing. If you tune for total numbers on a dyno, you are lean the minute you take it off the dyno. Dyno tuning is static tuning, meaning you are bringing in ambient air and stale air. Now when you are moving down the road you are bringing in forced air, that amount depends on the intake setup, and it is normally fresh air. So, when moving with forced air incoming, that A/F ratio leans out---still dependant on the intake setup. A good dyno tuner will know this and tune to a slightly richer ratio to compensate. Dyno's are good for a base line, but tuning to road conditions takes a really good eye/ear/feel/experienced mechanic/tuner to get what you are looking for. That person could spend hours doing this, but the feel from your butt will not lie---nothing ment there either. There are good mechanics out there, but few know how and what to do to get good power---especially with all the new electronics out there. They just become reliant on the technology and do not know how to use to their advantage. Just my opinion! disclaimer----none of the above means I really have a clue what I am talking about.
 

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Discussion Starter · #5 ·
I'm taking it back tomorrow as planned. What A/F ratio do I need to tell them? They asked me what the 9 needed as they mostly tune HD's at 13.5:1. This ratio sounds good but I read somewhere that 12.8:1 would give best roll-on throttle. I just wanted to hear some of your opinions here.
 

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I'm taking it back tomorrow as planned. What A/F ratio do I need to tell them? They asked me what the 9 needed as they mostly tune HD's at 13.5:1. This ratio sounds good but I read somewhere that 12.8:1 would give best roll-on throttle. I just wanted to hear some of your opinions here.
I would shoot for somewhere around the 13.2:1 range maybe 13.4 tops. Now, this is a subjective number due to the conditions in your area--temp, elevation and so on. Make sure they use SAE and not STD on their graph.
 

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Is there a difference in tuning for performance vs AFR?
I would think that the AFR set properly thru the dyno tune would also represent the best performance.
I read that the best performance AFR was at 12.8:1. Is this a good target ratio?
What would be the results of a dyno tune done in 5th gear vs 4th?

Reason I'm asking is that after my recent dyno tune it went from 108 ft.lbs tq down to 95. WTF! Also lost 1 hp which didn't get me excited but I can't choke down the tq number at a loss of 13 ft. lbs.
The bike runs good but feels like it has been neutered. I told the owner that I wasn't happy and he said to bring it back and they would run it again.
Their target AFR was set at 13.5 which I think is a little lean. He said that he could get more power but it would run hotter. That would mean that he is talking about setting it at a leaner ratio such as 14:1, right?
How did I lose 13 ftlbs of torque? I know that different tuners will give different numbers but this is way off.
hunt1moore,all good questions. each engine can have slightly different requirements. I think from memeory max power is suposed to be about 13.2 to 13.5, however due to excessive temps full load power afr's vary from 10.0 to 13.2. some engines are even set to 14.1 until tps gets to about 92% eg 200 landcruisers
Dyno numbers are only indicative of change and are not 100% acurate. I can change a car's dyno figures by over 20% without touching the engine.
Also cruise mixtures are normally about the 14's
what system are you using, is it tps based calc's or map based or both?
can you adjust the ignitinition timing?
cheers the gas man
 

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Discussion Starter · #9 ·
Who did you use?
A friend of mine Ben Edwards is the owner of a very repudible bike shop "Ben's V-Twins" in Matthews. Just as I was getting ready to set up an appmt in Concord it occurred to me that I needed to call him and find out where he gets his bikes dynoed and he said that he had a great technician that works with him and is certified. So, I asked if he could dyno my nine and of course definately could. I figured I would trade with him as I would hope he would with me if he ever needs cabinets.
My A/F is pretty much dead on at 13.5 so I really have no idea what happened to my tq. but like I told him, I wasn't going to complain until I had a chance to roll the throttle and do a seat-to-pants analysis. It failed. I could really feel the -13 ft.lbtq.
He wants to gather info regarding A/F ratios etc. before he looks at it again.
 

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Discussion Starter · #10 ·
hunt1moore,all good questions. each engine can have slightly different requirements. I think from memeory max power is suposed to be about 13.2 to 13.5, however due to excessive temps full load power afr's vary from 10.0 to 13.2. some engines are even set to 14.1 until tps gets to about 92% eg 200 landcruisers
Dyno numbers are only indicative of change and are not 100% acurate. I can change a car's dyno figures by over 20% without touching the engine.
Also cruise mixtures are normally about the 14's
what system are you using, is it tps based calc's or map based or both?
can you adjust the ignitinition timing?
cheers the gas man
I read different things about the A/F ratio for this bike. I have also determined thru lots of reading that these bikes like it a little rich, I may be wrong.
I have no idea what you mean by "system". The bike has a PCIII and it was dynoed using Dynojet Research, and, "CF: SAE smoothing:3" was on the chart
 
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