NO!!!


but what about aftermarket cams? surely the company would have given thought to those?

 

I'm sorry guys... It was late and my brain isn't so young anymore.. The crap about the MCM altering the suitability of my engine to gains from the megabomb was my mind letting me down. I'll delete that junk from my post as I can't stand to see it. The valve will unseat every 720 degrees regardless of its timing in relation to TDC.

 

Durielk, you seem to grasp some of the art n science of expansion chamber design but still have doubts... As I used to tell my students, the sum total of human knowledge on most any subject is at your fingertips. When I studied expansion chambers, it was with libraries.

 

Expansion chambers were originally designed as a fuel saving effort. It forced any fresh charge trying to follow the exhaust out the port back into the cylinder before the port window closed.



FMF describes it in part: The Megabomb technology is revolved to produce more low end to mid range gains as well as broadening out the mid to top end power gains over stock.

Meaning I think that their bomb section gives low-mid range gases a place ahead of the end of the exhaust system to expand, aiding performance; and broadening (but evidently not raising) mid to top end. The chamber on the FMF pipe isn't large enough nor probably in the correct location to be used as a reflective wave type chamber. It's more like a mini chamber similar to what's on street bikes now

Modern day performance road bikes have an exhaust (expansion?) chamber under the engine with shorty mufflers attached instead of four long heavy mufflers of years past. One well respected auto journalist suggested a chamber 8x cylinder volume a decade or so ago as a way to have your hp and keep the noise levels down at the same time.

 

That is what I was thinking, the 'mega' is a chamber that allows the pressure from the cylinder to expand into, without having to push on through the muffler. Once the valve closes, the gas will then reduce in pressure and proceed through the muffler. For a reflected wave, it is way too close to the valve.
Most megaphone pipes on a 4 cycle were installed way under the swingarm, not at the cylinder.
Now days, most high performance 2 cycles use reed valves, on the intake for sure, i don't know about the exhaust. Actually you can see the valve on the diagram since the carb it directly connected to the crankcase.

 

Okay Klxster, take the megabomb and hack it up and reweld the expansion chamber farther down the pipe

 

Just install it on the end of the muffler!

 

By any chance, did you try the stock header with the FMF PC4?

 

I have not dyno'd the stock header with the PC4 - yet.. I would expect that combo to offer a better over-rev than the DG-R as well as a slight powerband (HP and TRQ) shift toward the right. It could be the best combo if it preserves the TRQ, below 6500rpm, of the DG-R and also increases peak HP a little, like the full FMF does...
I hope to provide new data soon - my work has gotten crazy and I have very little time back home..

 

Does anyone know if slip-ons for the 2009+ KLXs are compatible with first-gen 2006-07 KLXs?

For the life of me I can't find DG slip-ons ever mentioning 2006-07 KLXs. Actually, I can't find 2006-07 KLX250s even listed or mentioned on pretty much any aftermarket slip-on manufacturer website.

Thanks!