Quote:
Originally Posted by NinjaRacer
Didn't check AFR after but it should be pretty close 13's like yours  Don't want to go much leaner. I heard timing is really high on these and compression is 13:1 like. . |
Tuning is best done with accurate data. New-gen has 11.6:1 compression. Pre-gen has 12.4:1 compression.
I'm trying for 13.0:1 AFR, but jetting is still way too rich in high-end where mains contribute most. With full-exhaust, free-flow air-filter and +20% more flow and +20% more power, I'm still in the mid-11:1 range with 97.5 mains (DynoJet 96), smaller than stock 98.
Here's various areas that's tuned by different parts of carbs. Horizontal scale is actually not accurate, should be a function of Throttle*RPM. At idle and low-RPMs, carbs don't generate enough flow & vacuum to open slides much anyway, so mains don't make much difference. I need to go down to smaller mains and add 1 more washer to flatten my AFR and get even more power, aiming for +25%.
No one I know in 250 Production class runs anything other than stock 98 or smaller with full-exhaust+K&N after dyno-tuning. That's 20% more flow minimum and +20% more power than stock. Removing filter completely made no difference. I did over 48 track-days on my race-bike last year on 97.5 mains and that's including some insanely hot days.
Here's plugs comparison of my 2008 250R race-bike with 97.5-mains and +20% more flow & power VS. my bone-stock 2008 250R street-bike with refurbed bone-stock carbs 98-mains (thanks Ducatiman) after 20-minute back-to-back sessions at Thunderhill on same day.
I don't have the before dyno-chart, but stock was off-the-scale richer at 9.6:1 AFR above 9000rpms. Here's comments by Ducatiman, the Lord of Carbs:
https://www.ninjette.org/forums/show...77#post1204277
"Just a heads up...there is a great habit of folks to overfuel (much more is better) when jet kits are installed."
"^ or the misguided belief that .....bigger = better ........more fuel= more power
Within my service, time to time I've seen some obscene jetting configs."