Half of engine is running rich

[eurico]

Hello and Happy New Year to you all

After carefully shimming valves, setting cams and TPS, balancing etc, I find out that the horizontal cylinder is running rich and the vertical is lean by plug inspection and sooty (er) right can. What gives? Everything is bog stock ('02 998)
Help is much appreciated

Thanks for reading
Eurico

[TomTom]

Throttle bodies out of sync comes to mind.
Check everything is fix and fine, if so you need to balance (sync) them.

I just experienced an 1198 with TB nut for rear cyl loose just a bit, it ran awful on low openings.
And a huge AFR difference between cylinders, so I stopped there and found the linkage was loose, fixed that and tadaa!

On 998 also check that TB opens fully, Ive done a few and on those they didnt, not even close, if so grind the stop to fit.
Cam timing and that gave 5-7 hp all the way from 6k up, silly

[eurico]

Thanks TomTom
I will check out what you mentioned.
Eurico