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Discussion Starter · #1 · (Edited)
Modifications from stock:
<BR>
<BR>Exhaust: standard headers, Norman Hyde silencers (with mute tubes fitted)
<BR>
<BR>Inlet: K&N pod filters / airbox cut away, 42 pilots, Thruxton needles with two shims, slide holes drilled 3mm, 140 mains.
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<BR>dyno' results:
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<BR>

<BR>

<BR>The dyno' operator said I was a bit rich at the top and bottom, bang on in the middle. The bottom end was tweaked in on the pilot screws, the top requires 135 mains instead of the 140. But that's only when it's revved over 6000rpm where I rarely go, so I'll leave that for just now. I'm pleased that my 'butt dyno' readings were near enough right to begin with.
<BR>
<BR>I didn't do any dyno' runs as I went along the well trodden path of snorkel removal, restrictor removal, de-baffling the silencers, re-jetting, etc. But I'd say there are two distinct jumps: from standard to modified standard inlet and exhaust, and from there to replacing inlet / exhaust with the pods and Hydes.
<BR>


[ This message was edited by: johnyC on 2007-01-23 18:48 ]
 

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Discussion Starter · #2 ·
Sorry guys,

I would go and 'gild the lilly'. I forgot about the curse of the hacker and now the post is full of BR bits.
 

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Nice looking curves. :-D

How's the seat-of-the-pants dyno feel?
 

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Regardless of your power and torque figures, your A/F ratio was lean, not rich like the Dyno operator said.
12:1 is the ideal ratio, your bike had that ratio at 2100 rpm's only and
at the top of the dyno run(6400-6500 rpm's)then was lean all the way.I wonder why the dyno chart shows the ideal A/F ratio at 13:1.
Also notice like the other member said the run was cut out short, there was more power in reserve.
I suggest you to work in the needles, specially if you use the mid range of the powerband.
I hope this help! :-D
 

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Discussion Starter · #5 ·
Bonnie1000th,

I already have Thruxton needles with two shims, but If you think I'm still a bit lean in the middle (I must say, the bike goes better than ever currently) it's easy enough to put another shim or two under the needles and see how it goes then.

I had a hunch that I was lean with the 140 mains, but the dyno' man says no :???:

The dyno' operator does a lot of race tuning, races himself, but I'll be speaking with him later today. I'll get back to you.
 

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<BR>On 2007-01-24 01:44, Bonnie1000th wrote:
<BR>Regardless of your power and torque figures, your A/F ratio was lean, not rich like the Dyno operator said.
<BR>12:1 is the ideal ratio, your bike had that ratio at 2100 rpm's only and
<BR>at the top of the dyno run(6400-6500 rpm's)then was lean all the way.I wonder why the dyno chart shows the ideal A/F ratio at 13:1.
<BR>Also notice like the other member said the run was cut out short, there was more power in reserve.
<BR>I suggest you to work in the needles, specially if you use the mid range of the powerband.
<BR>I hope this help! :-D
<BR>

<BR>
<BR>Most tuners, myself included, usually looked for a narrow band of 13.4-13.8 : 1 as an ideal performance Air Fuel ratio.
<BR>12:1 is a RICH reading, not lean, as you only have 12 parts O2 to 1 part fuel, whereas a 14 : 1 ratio is lean as you have 14 parts O2 to 1 part fuel.
<BR>
<BR>Johnuc's chart is a GOOD looking AF chart, especially considerring they were able to lean out the near 12:1 numbers on the bottom with the pilot screws.
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<BR>Your Dyno operator KNOWS what he's talking about Johny, listen to him.
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<BR>Good deal Johny......looks real good!

[ This message was edited by: kliff on 2007-01-24 06:59 ]
 

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I must first preface that I don't know sh!t.......
I only know how various and assorted Dyno runs and Dyno operators have responded/reacted to the runs of my past: Sportster, Roadster, Sprint, two Bonnies, and one FZ1.

And for a bike with two carburetors (problematic from the onset), that's a run that would suggest that you NOT TOUCH A THING! If your Dyno operator attached his A/F sniffers to those bung fittings at the front of the headers (instead of stuffed up the pipes AFTER the cross-over tube), made sure the filters on his machine were virgin clean, and had all day to mess around with your bike...... his efforts might result in an improved run. On the other hand, he could muck up an already good thing.

Once dialed in on the Dyno, then a guy might wanna be so anal as to attach a portable sniffer to the bike and take it for a spin under a variety of conditions. Only to discover that another day or two could be wasted trying to eek out a better ratio..... but it would then be ideal for only THAT day, over those roads, under THOSE conditions, with temp's & humidity at that time of year.

Your run has resulted in a tad rich upon start-up, and that could be a good thing..... one never rides there anyway. You have a relatively smooth ratio/run with an absolute MINIMAL characteristic 5500 dip! And you're right there in the safe & somewhat environmental friendly zone. With regard to cutting it short, it's obvious there would be nothing more to gain by continuing to spin her up another 900 rpm. HP & torque figures themselves mean little, it's HOW the power is delivered...... and your bike be DELIVERING!
:cool:
 

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The ideal, stoichiometric fuel-air ratio is 14.7:1.

Dangerously close to lean and awfully hard to maintain in a carburatted, non ECU engine.
 

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On 2007-01-24 08:58, panthercity wrote:
The ideal, stoichiometric fuel-air ratio is 14.7:1.

Dangerously close to lean and awfully hard to maintain in a carburatted, non ECU engine.
Not in my engine! I thought ideal was 13-1. you're saying almost 15-1, that would run hot as hell! No thanks!
 

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Discussion Starter · #11 ·
Kliff,

Aw thank goodness for that. I'm just back from a 70 mile round trip to the bike shop where the tuner works during the day, he insisted he was right about the mid range, but there is a wee problem with the charts I posted. All the way home I was thinking how to get round the first rule of holes (when you're in one stop digging) :-D but I'll just spit it out:

The reason for the 'missing' part of the line after 6500rpm is because Willie gave me the wrong printout. I've got run 03 which didn't see the bike revved out, the later runs saw the bike hit the limiter and this is borne out by my own tests on the road up to the shop today. I hit the limiter in 2nd (indicated about 70+) and also in 3rd on an 18t g'box sprocket. Since this was around 95mph, allegedly :) , I didn't try for the limiter in 4th or 5th. The bike does run beautifully, you'll just have to take my word for it and take the chart with a pinch of salt. I'll try and get the final run posted, but I'm off to work next Monday and Willie might not be at the dyno' room before then.

The rich bottom end as was: righto, this is a bit of a story too. Early on before I was hacking lumps out of the airbox, I had the standard 40 pilots adjuster screw turned out about 3 1/2 turns, which I thought was at the outer edge of adjustment. I opted for 42 pilots with the screws turned back in. However, I also changed the screws for the older model Bellacorse ones at the same time. Bad move I know, shouldn't change two things at once. I knew that the setting was too rich some time ago at 2 1/2 turns out, the plugs were sooty, but it started and idled ok if a bit lumpy off a closed throttle. I had the screws in at 1 1/4 turns for a while but didn't think I should go in any further, I can't believe I allowed my common sense not to see that the pilot setting was too rich all along.

With the gas analyser to set the idle up, the setting now is 1/4 turn out!!! that's not a mistake, Willie had it running with the screws almost fully in and we had to drop the idle right back down. It was away above 2000rpm with the pilot screws where the analyser said they should be. I'm sure the 42 pilots are not THAT far wrong, they're standard on the other 270' motors. I can only surmise it must be those Bellacorse screws. I'm thinking about putting the original screws back in, except the bike starts, idles and pulls from nothing so smoothly now it's adjusted correctly. What dyno's are for I guess.
 
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