Quote:
Originally Posted by jkv357
Interesting. Was this done on a Ninja 250 engine? Are you sure the "very small pod filter" wasn't just restricting air flow? What was the main jet with the stock air box, and how did you determine you had the correct jet size for the modded filters [COLOR="Red"[/COLOR] - especially if it lost 7 HP?
How is backpressure a myth? Have you ever altered a muffler and noticed a negative change in throttle response? Gaining top-end power but losing mid-range? As you increase the header dia you will lose velocity but gain max flow. That's fine if you want peak power, but it's not going to help cruising MPG. Why do most engines run better with a muffler than just a straight pipe?
Your turn...
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All jetting was on Dynojet dyno with exhaust sniffer.
Stock airbox main was 155.
Small filters DO restrict flow due to pressure change.
Going larger on exhaust only affects response badly if you are already on the large side, and going larger. If you are on the small side to start, you will not loose throttle response even at low revs.
Most people don't want to spend the money on dyno tuning, which is why alot of bikes DO run better with a muffler. It IS all in the jetting to get the best performance out of the mods you make.
Lots of motorcycle intake ports are very large, too large and you can gain big response in reducing the size of the ports, but big carbs, cams and open exhaust make this MORE of a problem, ESP on the bottom end performance.
Combine this with the fact that most motorcycles have poor ignition setups, that are computer controlled, and need to be advanced a good deal to bring bottom end performance to where it should be.
Example, my bike from idle to 3k rpm's fires at 5 degrees before TDC.
Above 3k , it is 31 degrees before TDC.
Now, with E-ZERO and proper jetting, the bottom end response is much better, AND it makes more power up top.
With E10 and proper jetting, below 3k is only usable in the first 3 gears, but only at light throttle in 3rd. Makes less power up top as well.
Now, if I could advance the timing the E10 should work as well as the E0 in power and response.