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View Full Version : Stock back pressure on Gixxer 750?



mmbabar
08-01-2009, 02:53 AM
I have a GSX-R 750 -92 (water cooled) with a 4"ID SS UNIV:2.00"INLET,16"LONG. Got the bike with the exhaust mounted. How many discs do I have to use to get the same back pressure as the stock exhaust?

hugger
08-03-2009, 11:04 PM
I have a GSX-R 750 -92 (water cooled) with a 4"ID SS UNIV:2.00"INLET,16"LONG. Got the bike with the exhaust mounted. How many discs do I have to use to get the same back pressure as the stock exhaust?

Unfortunatly we do not have that information available. What you need to do is start with a specific # of discs nd then go up or down depending where you want the power to be. If you email me I can send you some information that may help you in tuning the SuperTrapp to your bike.
hugger@supertrapp.com

kz550
08-04-2009, 11:39 AM
I think specific data on flow rates for each motorcycle would be difficult to accumulate.

Based on my universal 4" x 13" closed end-cap, I'd say start with 7 diffuser discs then follow Hugger's/Supertrapp's FAQs on disc tuning (http://www.supertrapp.com/resource/faqs.asp#9). It boils down to preference.

Originally I wanted a stock like quiet, but then got bit by the intoxicating power from running more discs and the exposure from having an exhaust note that was just loud enough for mountain critters (deer mostly) and motorists to hear. I'll also say that there's a nice bit of power to be had in combination with more discs, if you're willing to rejet. Raise the jetting 2% - 4%, i.e. stock main jets 150 * 2-4% multiple (1.02 to 1.04) = 153 to 156. Use 153 for up to 9 discs and 156 for 10 or more. Shimming the jet needle up 0.8mm+ (http://www.zxforums.com/gallery/showphoto.php?photo=810&size=big) is also great for boosting torque, with or without changing the mains, depending on what you're looking for. Always take into consideration altitude, because if you live in Denver, you may only need a freer flowing pipe without any jetting mods.