 Air/Fuel Ratio
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The recent threads about pilot jets and dyno charts got me digging out my dyno from last April when I had Fast Fred's carbs and head put on my bike at the dealership. It was super lean at the low rpm's but the smallest pilot jets they had on hand were 45's. So off they sent me with the following set-up: 155 mains, 45 pilots, TBS needle (I think that's what Fred said it had?) with one shim, Screws 4 turns out. I've since put 48's in and I'm still about 3 turns out with them(?). My bike still doesn't "feel" like it's dialed-in. I've also added the procom ignitor with the rev limit set at 8000. So, I'm asking for inputs from my friend's here. Below is the Dyno showing how my bike is going from lean to rich to lean (sorry it's a big file and the air/fuel line is very faint). So what say ye experts? 
'05 America, 904, K&N pods, British Customs Bomber Exhaust
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Re: Air/Fuel Ratio
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Joined: Feb 2008
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Really need to know what FF did to the slide and spring, if any. Also need to know exactly what needle is in it. Prolly is a TBS, however what's the 4 digit code on it?
Don't be too concerned about the low RPM lean spike if the dyno operator whacked the throttle during the runs. Who specifically at Eurosports operated the dyno?
What pipes are you running?
Which pods?
Any idea what the float height is?
Which cams?
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Re: Air/Fuel Ratio
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Joined: Mar 2008
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I think he said he drilled the slides and changed the springs. To what I don't remember. Has anyone been in contact with him (Fast Fred Hether) in the last year? He's not answering emails or returning phone calls. I gave up a long time ago trying to get a response from him.
'05 America, 904, K&N pods, British Customs Bomber Exhaust
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Re: Air/Fuel Ratio
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Joined: Feb 2008
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Loquacious
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Loquacious
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If he drilled the slide transfer ports and went to lighter springs and you are running pods then what you are seeing on the dyno sweep test at low RPM is the lean spike when the slide is opening too fast from a setup that isn't in proper balance.
Don't assume that the pilot is too small or the screw isn't properly set because the slide is raising too fast on a sweep test.
I've done a lot of spring testing & can prolly help you. In order to do that we'll need to know EXACTLY what the current situation is with the air port dimension, current vaccum spring, & needle.
See if you can get answers to the other questions & we'll go from there.
One thing is certain - your bike isn't optimally tuned, and it CAN be improved!
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Re: Air/Fuel Ratio
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Joined: Feb 2008
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Ahh, some of the answers are in your sig. Was that stuff also true for the dyno run?
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Re: Air/Fuel Ratio
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Quote:
some of the answers are in your sig. Was that stuff also true for the dyno run?
Yes. except the pipes were Stock with 2 baffles removed (Chevy 605's). I think the BC Bombers are about the same as far as back pressure.
'05 America, 904, K&N pods, British Customs Bomber Exhaust
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Re: Air/Fuel Ratio
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Joined: Feb 2008
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Quote:
...pipes were Stock with 2 baffles removed (Chevy 605's). I think the BC Bombers are about the same as far as back pressure.
Well, I'm not so sure that is true, although it is certainly possible.
I also have no idea what size FF drilled out the slide air ports to, or what springs he used, but let's presume for discussion that the ports are now approx. 3mm +/-, & presume that whatever he did to the springs are now sub-optimal.
All other things equal (& in practice they never are) the 904 kit would tend to increase vacuum all by itself, as compared to a stock bore motor. Drilling the air ports (too much) & going too short/light on the springs would only make a transitory lean issue worse.
One low cost thing you could try that ought to improve off-idle driveability RIGHT NOW is to replace whatever slide springs FF installed with a set of OEM slide springs, for starters. The OEM springs can be tweaked, but you gotta know what you're doing, have a reliable means to measure it, and have a reference point before you make more changes.
You also really need to confirm which needles are in there now - although you could speculate & act on the speculation, you really need to actually check the 4 digit code to know what you are dealing with. Once we know that then I'll have a recommendation that will likely get you closer before your next dyno run. That's an easy top-side check.
If you can get any of the other data that I asked about that would help too.
IMO the pipe change alone is a potential game-changer for the mains, but you'll either need to install an A/F meter or go back for another dyno run with the current pipes to verify. BTW, the last time I was on that dyno (2010) the dyno's A/F meter crapped out, however that should have been fixed already.
If Bill H does the test ask him to also check the AFR at idle, light-load cruise (whatever speed that is for you), & simulated hillclimb.
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Re: Air/Fuel Ratio
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Ken, thanks for your inputs. I'll have to check what needle I have in there now. The good news is I still have my stock carb. I can use the springs from that one. Can I also use the slides from it? BTW, Glen is the one who's done all the work on my bike including the dynos.
'05 America, 904, K&N pods, British Customs Bomber Exhaust
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Re: Air/Fuel Ratio
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Joined: Feb 2008
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Your bike started out as a 790, so the cams are good.
The slides from your stock carbs should work. That may not be necessary if the OEM springs calm down the slide opening, however. That said it would be helpful to know what the air transfer port diameter is. In my experience small holes like that can be difficult to measure with great accuracy.
Try the springs first & see what happens.
The bike should not need 48 pilots; like I said, I think yours has a slide-rise issue as a consequence of FF's tuning, & you need to rule that out first.
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Re: Air/Fuel Ratio
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Joined: Jun 2009
Posts: 84
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I found this on another thread from someone who had Fast Fred carbs. Hopefully it will help some.
I think I finally have these set up where I like them, and it's definitely an improvement. The only thing I have to figure out is if I am keeping the Kawasaki springs in them or if I will go back to the stock springs. The stock ones may be good for the bored out carbs, as they pull more air to operate the slides anyway. More test riding to do. Still need to get to the dyno and make sure everything is jetted right, as soon as I can after the new manifolds get here.
08 America, A/I &, Calif emissions "stuff" gone, air box removed & battery relocated, billet intakes, UNI Pods, 145 mains, 42 pilots, Stage 2 igniter, intminators, 813 cams, Progressive 412's, modified seat.
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Re: Air/Fuel Ratio
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Joined: Feb 2008
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Re: Air/Fuel Ratio
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Quote:
Well Pete, any progress?
No, I haven't had a chance to change the springs or check which needle I have. Soon I hope. I'm waiting for my painter (Jay, the new service manager at Eurosports)to finish my tins. I'll definitely let you know as I'm sure I'll be needing some help! 
'05 America, 904, K&N pods, British Customs Bomber Exhaust
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