Hawk is here, yay!

[pete]

is it possable for you to fit up a wide band AF gauge to set the carb up...
i thought I had the Koso/OKO right... lot stronger power though the whole rev range
motor ran great everywhere...
but once the AF gauge was fitted... god dam it was rich... these carbs seem to run very well on the rich side...

my AF ratios are after setting with the gauge...
idle... 14.3 - 14.8
light cruse 13.7 - 14.2
light acceleration higher gears 13.2 - 13.6
acceleration from 1/3 to 2/3 throttle 12.9 - 13.4
WOT 12.4 - 12.9... see the power jet really richen up the mixture at
full throttle..

edit....
these numbers are still a tad on the rich side... but thats what i want
my bike is never at a cruse... on & off the gas hard all the time accelerating
or brakeing.. A/F ratio is set to suit what the bike is used for...
thats the great thing useing a A/F gauge to set the jetting..

i had to change the needle to a leaner one "slower tapper" to
get the mid range ok...
went from a 1mm point to a 1.4mm point...
mikuni needles seem to be the best match.
57mm long with a 2.5mm top DIA...

A A/F gauge is worth useing.
What you think you have & what you really have can be 2 diffrent things...

.

[Megadan]

Originally Posted by pete

is it possable for you to fit up a wide band AF gauge to set the carb up...
i thought I had the Koso/OKO right... lot stronger power though the whole rev range
motor ran great everywhere...
but once the AF gauge was fitted... god dam it was rich... these carbs seem to run very well on the rich side...

my AF ratios are after setting with the gauge...
idle... 14.3 - 14.8
light cruse 13.7 - 14.2
light acceleration higher gears 13.2 - 13.6
acceleration from 1/3 to 2/3 throttle 12.9 - 13.4
WOT 12.4 - 12.9... see the power jet really richen up the mixture at
full throttle..

i had to change the needle to a leaner one "slower tapper" to
get the mid range ok...
went from a 1mm point to a 1.4mm point...
mikuni needles seem to be the best match.
57mm long with a 2.5mm top DIA...

A A/F gauge is worth useing.
What you think you have & what you really have can be 2 diffrent things...

.

I have a home made tailpipe sniffer wideband that I can use, but it's not very convenient to actually ride around with. I know my bike is a bit on the rich side, but not by much. Plug checks (i have a whole mess of coppers I use to help tune lol), engine behavior, and other factors have me to a point that I am pretty sure of where my bike is fueling wise. Would I like a wideband installed on the bike? Absolutely.

My methodology involved a lot of carb removal to do some experimentation. Aside from plug chops, there is also behavior.

Example. A 110 main with the intake and exhaust showed clear signs of being lean at WOT, even with the too big 30 pilot jet taking up some slack. On the opposite end of the spectrum, the 125 pilot was too rich - especially with the 30 pilot and would instantly bog when full throttle was attempted.

I left the 125 main in place and put in a 25 pilot. The 25 pilot, even with the tiny bit of extra fuel from the too big main, was a touch on the lean side at light throttle slow speed cruising - showing the classic signs of backfires, pops, hesitation and herky jerky throttle. The 125 main was still too big and would bog down at wide open.

I left the 25 pilot in place and dropped to a 120 main. slightly too lean pilot jet combined with a slightly too rich main. No bog at wide open anymore, but would have a slight surge once in a while when rolling off wide open. I left in the 120 main and installed the 27.5 pilot. All light throttle slow speed hesitation was gone, throttle is smooth and idle mixture takes 1 turn or more out. However, the occasional stumble rolling off of wide open ever so slightly cam back.

Leaving the 27.5 pilot in place, because it's perfect, I dropped down to the 115 main. Excellent behavior all around, top end of the throttle spectrum was responsive, no roll off surge. I then did a plug chop on a fresh plug and the plug was slightly off-white. This is when I put in the 117.5, and after a plug chop on that jet - a dark tan/brown. Also, the tried and true "top speed" method gave the nod to the 117.5 main, able to achieve an average of 1-2mph on the same road, on the same day, in more or less the same temp and humidity. I can swap main jets in about 10 minutes even on a hot bike lol.

It may be a bit on the rich side, but not by much. With aircooled motors I always favor the richer side of things, at least in the hot months here. That is also why I moved the needle up one notch. I am going to go ride it again tonight and see how it behaves in cooler weather.

If I were to put the 115 main back in and set the needle in the center, I am certain this bike would be more or less dead perfect for what I call "OEM" carb tuning. Aka ever so slightly lean, but not too lean, and get the ultimate fuel economy. I am fairly certain I can move the needle back to center with the 117.5 and be fine, and I may still do so, if for any other reason than fuel economy. I will wait and see how it behaves in cooler weather.

As far as the OKO/PWK carb that I have. It already has a Mikuni needle jet in it. I will have to measure it to get an idea of the taper.