Hi everyone! I need some help so what better place to go than this. Hers the scoop


I have a 97 bird. I had to replace all the panels but had to do it over time. Meanwhile I got a pair of migs, a factory pro jet kit, a K&N filter and had my pipes (FI pipes by the way) Jet hot coated. Well after working with factory pro to try to get it running right I decides to go back to stock. I got a stock filter from Mike (Bartonmd)...started a new job so gonna get that to ya on friday Mike...

Anyway before I went back to stock I had 148 mains accross the four carbs and the needle clip was on the second from the bottom, pilot screw was 4 turns out from bottom. I had major cruise problems, good idle and good top end. When I closed the choke the stumble would lesson but didnt go away. I have since replace the stock filter and put the pilot screw to 3 turns out and 142 on outside carbs and 145 on inside like the european bikes are. Also put a small washer without the stock washer on the needles. It helped but the stumble is still there. I am at a loss...I feel like its running lean but I am not a carb guy...I have been working from the factory pro tuning instructions and havent solved the issue. Can anyone help me with something else to adjust or check? 29 mpg is not what I want.

Thanks

J

Needle jets are set rich, put the clip on the second ring from the top & you may have to play with the pilot screws alittle after that. my .02c

Second from the top is where factory pro suggested I start..that was the same time as using the 148 jets at 4 turns from bottom. If I were running too rich wouldnt the choke make it worse?

I had similar problems and ended up taking the bike into a shop, who later crashed the bike but in the mean time, my Af screws were 3.75, e-clip was 2nd from the top, 155 mains, not sure if they changed pilot jets or not. I have a delkivic SS 4-1-2 header with two brothers M5 VALE carbon canisters. BMC race air filter, factory pro ignition advancer, and TI jet kit.

The choke should not be used to diagnose an issue, while it may be true it could also be wrong, due to several other variables.

You can also use the pilot screws as a bandade for improper jetting, If you are jetted too rich then turn clockwise, jetted lean counter-clockwise. This will not cure the issue but may help smooth it out some. I would recomend staying under <4 & no less than 3 on the pilot screws.

I have a 98XX. Arka pipe, Ti jet-kit. 145 mains, 2nd from top on the needles, 2 1/2 turns out.
Dyno w/O2 sensor reads 14-1 AF mixture. I am @ 410ft elevation and I always head for the mountains.
That's why I want to run @ 14-1 AF ratio. Goes like a MoFo.

imho, I think 4 turns out is way too much.

Cal

I'm running the stock header with Yoshi slip-ons, with a Factory Pro jet kit with 144's all the way across, and exactly how they recomend the needles be set up (2 from the top, maybe??) for stock pipes/street baffle slip-ons, running 3.75 out on the idle screws...

The thing that jumps out at me about your setup is the FI header...The FI header is paired differently than the carb'd header, during the first "2" part of the 4-2-1-2. The FI header is built for midrange torque (i.e. more flow in the midrange), while the carb'd header is built for top end power. This will substantially effect your jetting settings in the midrange, and I don't know that anybody's got a "canned" jetting setup for that exhaust setup.

Mike

Ironicly the mid range is where my problem arises. The improved midrange was what I wanted when I went with the FI exhaust. I am gonna increase the main to 145 and the pilot jet to 45 or should I go 48? then I will play with the needle then the pilot mixture. What do you all think?

J

It's not ironic at all... It's completely expected...

I'd keep the ~144 mains (FI header doesn't flow as well at the top end as the carb header). The main jet is really only for WOT/redline... The needle taper and position does most of the work in the midrange. The pilot jet does most of what you're seeing at steady state cruise at 50-65mph on this bike.

Mike