Hi Guys, Just registered, and first off can i just say i am stoked that OS is back!! I have missed this site and the guys and girls here :-) Ok - I have a 1993 GSXR 750 WP, which came to me in a right state and i have been building a 'fighter out of her for the last 2.5 years. She is now on the road, and running almost beautifully again. I say almost, because since I got it its been running rich. Black smoke from the exhaust, thick black soot on the plugs, and smells go-awful if you run it in the garage and not outside! On initial investigation, it had a Scorpion race can so i checked it had been jetted for this. Looking inside the carbs it seems that it has been Dynojetted and I believe they only ever did a stage 3 for this model of GSXR (?). All looked good in the carbs, but i cleaned them out while i was there and gave them a balance - still running rich. Checking the fuel/air screws, and reset to factory - still running rich. So i checked the airbox. Standard box and standard aftermarket filter! So i bought a K&N filter for the airbox - still running rich. Fitted one grade hotter plugs - still running rich.... Grrrr...... So, then i bought some cheapie secondhand K&N pod filters from (that popular online auction site), and fitted them. Whilst they didnt fit quite right and leaked a fair bit, this seemed to improve the richness a fair amount. Happy that i think im now on top of the richness, i invested in a new set of RAMAIR pod filters.... fitted and finally, the richness is abating!!!! At least it isn't blowing black smoke unless i give it a fistfull, and the plug ends are starting to go tan - wayhey!! Or so I though..... Now i seem to have developed a flat spot, and quite a big one. I cant tell you the exact rev range of this as i have an aftermarket KOSO clock fitted, but it is the low rev range, i would say around 4K, and it seemed quite a big flat spot. It feels like its getting too much air now, if i open the throttle quick it hits the flat spot and struggles, if i gentle roll the power on it does better, and applying the choke a little seems to help. So is this fuel/air mix do you think? If i adjust this, wont the bike go back to running too rich again? Am I missing something obvious? I dont really want to take this to a garage, as I am currently priding myself on doing this by myself - but without a rolling road, this is starting to get tough to diagnose! Any suggestions, or anyone that has experienced similar? Ta,