ninjette.org - View Single Post - 2007 250ZZR Carb cleaning - any mods should I do while the carb is apart?

greg737 · October 23rd, 2019, 04:23 PM

Does your ZZR have an aftermarket exhaust on it? I ask because the OEM Keihin carbs are very well matched to the volumetric efficiency of EX250's 125cc pistons (when the bike's original equipment airbox and exhaust is in place).

My advice, don't rich-it-up unless you've done mods that have increased the pumping efficiency of the engine (aftermarket exhaust and airbox modification for better flow).

The smaller the piston the more delicate the balance is between rich and lean (or too rich and too lean), just a little extra gas in a small displacement cylinder can take things too far. I've seen the bad results with guys working on Suzuki GSF400s, which have 100cc cylinders. They rich-up the mixture to the absolute limit in search of extra horsepower and end up in a constant struggle for usability everywhere in the rev-range except for high-rpm wide-open-throttle.

October 23rd, 2019, 04:23 PM	#7
greg737 - Name: - Location: - Join Date: May 2009 Motorcycle(s): - Posts: A lot.	Does your ZZR have an aftermarket exhaust on it? I ask because the OEM Keihin carbs are very well matched to the volumetric efficiency of EX250's 125cc pistons (when the bike's original equipment airbox and exhaust is in place). My advice, don't rich-it-up unless you've done mods that have increased the pumping efficiency of the engine (aftermarket exhaust and airbox modification for better flow). The smaller the piston the more delicate the balance is between rich and lean (or too rich and too lean), just a little extra gas in a small displacement cylinder can take things too far. I've seen the bad results with guys working on Suzuki GSF400s, which have 100cc cylinders. They rich-up the mixture to the absolute limit in search of extra horsepower and end up in a constant struggle for usability everywhere in the rev-range except for high-rpm wide-open-throttle.