Author Topic: Sport vs Race and Hyper Race Exhausts  (Read 3857 times)


  • Guest
Sport vs Race and Hyper Race Exhausts
« on: December 29, 2016, 09:04:37 AM »
Sport Pipe Benefits: 6,000 - 11,500 rpm power band operating range:

Useful low rpm torque = less annoying constant downshifts + clutch slipping while setting off in 1st.
More torque allows for pulling higher gearing ratios.
Less explosive, non light switch power band = easier ride.
Low vibration due to lower crank bearing rotational speed.
Limited maximum crankcase vacuum pressure, less fuel pulled through carb jets = good fuel economy.
Require small, more fuel efficient carburetors = good low rpm torque and fuel economy
Low wear n tear on engine parts and cooling system.
Low risk of overheating and seizures, crank rod breakage, crank bearing or gudgeon pin failures.
Don't require lightweight internal flywheel rotors in order to prevent snapped crank rods destroying engine cases @high rpm.
Usually cheaper to purchase.

Race and Hyper Race Benefits: 8,500 - 16,000 rpm power band operating range:

Shifts a power band higher up the rpm range, offering more peak horsepower in situations where possible to use.

Not many benefits in the 8,500 - 16,000 rpm range is there? ROLF! ;D try entering the power band with a race or hyper race pipe on a windy day' and your hopes for dislocated shoulder sockets and squashed flies on your helmet will be immensely short-lived. No matter what you do with smaller front / larger rear sprockets' forwards momentum just won't happen. As you begin climbing those steep inclines to higher altitudes... air becomes less dense (thinner) and the carb A/F ratio becomes richer.

At this point' the combustion chamber is being provided with more fuel/oil than it can burn and is now slowing down piston and crank rod movement. Some high rpm pipes require at least a 24mm carb to counteract the fuel/air limiting barrier for higher rpm's, larger carbs like Keihin PWK copies means the OEM Airbox boot will not fit the carb intake diameter and the OEM filter sponge is simply too restrictive for the increased airflow - especially with flat slide and D slide designs.

So owners resort to an open type filter or go kart Airbox as a substitute' open or "pod" type filters are more sensitive to varying weather and altitude changes... making first world problems even worse. Open filters also don't cope so well with low vacuum pull signals = reduced pickup and throttle response @low rpm, and i have the "been there, done that" experience to post such claim from a few years back when the brand new 35mm OEM Airbox boot hadn't been sitting on the cold garage shelf for long enough for the rubber to cold shrink to 34mm after removal from the packaging. This also meant fitting a shorter intake manifold so the semi-open type Polini 48mm filter had enough shock absorber clearance...

Few months later' when id finally had enough of the deafening filter noise i retried the 34mm adapter with the OEM rubber boot and "ba da bing ba da boom" fitted perfectly :) so reinstalled the OEM intake manifold with a new gasket and the engine ticked over at idle and responded much better to throttle openings with a nice low rpm boost, end of script.

Moving on...


  • Guest
Re: Sport vs Race and Hyper Race Exhausts
« Reply #1 on: December 29, 2016, 09:10:58 AM »
Protecting the pipes:

Without some kind of stone chip shield' VHT paint gets scratched off and rust begins forming, which means repainting the pipe area behind the front wheel. Install a universal 2 stroke motocross pipe shield to deter this common issue with non-japan black finished steel pipes. These universal 2 stroke aluminium pipe shields / guards can be found in most ebay stores' look for the cheapest price though, because some stores are put their own labeling on the sale listing and charging twice the price for a not so expensive item.

These shields do tend to rattle a bit at low rpm' but you can always saw it shorter since only the widest parts of the expansion on a side mount pipe would scrape off the ground in falls. The idea for best paint protection results is to bend the shield round the downpipe and situate as close as possible to the exhaust port area. For those of us who ride RS GPR sport bike models with lower fairing panels removed' install the shield like so...

Should you heat wrap an exhaust?

Using heat wrapping on exhaust pipes quietens down the tin can noise which seems a nice benefit, until a dozen cracks in the metal begin to appear. Arrow exhausts are made from very thin sheet metal... making them louder than others and are a prime example for developing cracks. Therefore' heat wrapping an exhaust pipe only makes first world problems much worse and costly in the long run.
« Last Edit: January 16, 2017, 01:03:22 PM by Jerry-Built Hustler »