Having bought a BEET system of a ZX-4 which was originally for a ZXR and zimm confirming they are much the same engines I delved a little deeper
1st of for mid-range benefits nearly all performance pipes use a 4-2-1 configuration, this can be very apparent or like the BEET, Akro' , Yoshimura, Kerker and a few other a short plate in the collector.
My personal preference is a system that makes a definitive 4-2 switch, K-Factory make some of the best of this type and it is allowing the exhaust gases to combust before being thrust into the 2-1 chamber.
The "S" link pipe along with can entry/exit and header pipe diameters determine how well the engine will pick up from pre-determined rev's. a nice big bore will allow the carb's to draw in a larger volume of air/fuel. Again specialised pipes can be seen with headers that expand after exit or "S" pipes that increase in size - all these contribute to the resonance of the system and how it performs.
My Yoshimura system is fairly standard headers going into a 54mm "S" pipe with a 54mm exit on the can - I swapped the "S" pipe for a 60.5mm link pipe going into a 60.5mm can and the low end grunt was awesome - this allowed my carb's to draw in a greater air/fuel mix.
Well, i just noticed this system for the ZX-4 , it has all the traits of a very good power pipe. A true 4-2-1 set-up for your mid-range going into a big bore "S" link pipe and a big exit on the can. Perfect for FCR users
I assume the SP models run 32mm as standard ? You can also get 33mm too , now 1mm doesn't sound much (phnarr phnarr) but you'll gain another 3-4 hp over and above and a constant rise on your actual power curve.
RPM also do 4-2-1 systems but I am not sure that the bore of the pipes after the collector is as big as this :
Any thought on this?
BTW, there are two of these systems available.
Drew San.
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