Custom Exhaust

[PowerDubs_imp]

I never said you were damaging it.

Engines can run a wide range of less than ideal fuel ratios- it takes a pretty extreme in either rich or lean to cause a noticeable problem.

Honda themselves had heat issues when designing this engine- that is part of the reason why even our spark plugs have their own cooling fins. Personally I prefer to cool with fuel as opposed to lean out and create more heat.

Modern fuel injection spray & head design burn so efficiently that plug read is useless.

Your exhaust doesn't put the bike out of the range of where it will run. But the bike doesn't know your exhaust is even there- it does NOT adjust.

Trust me- put a stock bike on a dyno and look at the A/F curve- then take out the cat- redyno and look at the A/F curve. It will lean out. Would be interesting if the cyl head temps were read- as they should increase as the air ratio climbs.

The O2 sensor is narrow band- it only knows 14.6 14.7 and 14.8 - that's it.

Anything else and it is out of range and does not do anything whatsoever. It is for emissions purpose only.

There is no running target AFR- there is only static map injection pulse. Nothing changes other than airbox atmo pressure shifting the whole map up or down completely and simplistically for altitude and air temp- it doesn't change fueling at individual rpm or look at any result and compare to any target- how could it- there is no feedback loop. It's a pre-set dumb system- as are pretty much any other bike, car, etc. That's the entire reason tunes exist- the map actually gets modified- the fueling actually changed.

That's why even a tune- like Guhl or any other tuner- is still only ideal on that bike, with whatever mods on that day. Once he tunes it- adjusts the map to what a/f he wants- it stays there, locked again as a static map. That's what makes the power commander with auto-tune box appealing- it actually has live real time feedback and adjustment with a wide band O2 sensor that looks at ALL the range of A/F ratio in the exhaust in real time for all throttle position and rpm and adjusts based on what target you design the map for. You can even have it tune for each individual gear you are in- as the engine load does change the #'s a bit.

I'm about to take it a step further than anyone else has done on this bike-and run a dual channel autotune box with 2 WBO2 sensors so I can tune the left 2 cylinders separately from the right 2. I don't expect it to make any difference- but I like to play- and look at generated data. I have the parts, and new 4-4 exhaust- just need to get around to installing.