I can be a sarcastic guy too, so understood, but that wasn't my intention on this case at all. And re: other forums, some dudes just like to be internet tough guys, don't they! And once the dog piling starts, things can get out of hand quickly.

If you ever stumble across the curves or BB's explanation, please pass it along here somewhere, either in a post or a PM. I'm curious.

 

This is one claim made by Bake, who was helping Bill when he first installed his 351 kits, I know there is a specific chart in the klx250s monster thread, I'll do a better search when I have more time tomorrow. FMF PowerBomb header - ADVrider

 

FWIW, my bike revs just fine to factory redline with the KLX300 exhaust, which has the larger diameter head pipe. Before the 351 kit I had wondered about people saying it really didn't rev past 9k. Mine does just fine. You can feel power drop off a little, but not enough to think about.

I don't like the idea of having to repack a muffler either; but clearly this thing needs to breathe a little better, and I don't really see much other choice. And I just can't see spending $300+ on a "name brand" system. Though maybe at some point I will; I have too much other stuff to buy in the short term, so this purchase will be put off til probably Summer.

Rob

 

Oh i didnt mean to suggest mine won't rev, ive been up to 10k rpm, but it doesnt have as much power so i choose to shift at 8krpm

 

KLX300 header is only bigger at the muffler flange. Otherwise it is the same diameter.

 

When I was selling the KLX300s, the hop up tips for quick power increase was a bigger carb and a larger ID more open exhaust. I forget what carb, it was 2004 or so when I last sold them.

If I had the ability to TIG weld or had someone who could do a good job I would make my own pipe. I did that with my SR500. Do the appropriate research to learn how big and how long to make it (yes, it is science) and build the pipe. My SR was pretty well proven to work with a 1-5/8 ID pipe 33" long (if head port to the valve was included it would add 3-4"), lots of work done on them back in the 80s that I knew of proved the point. Here's a discussion on the topic and a program that can be had to build exhausts.

Once you know how long to make the pipe then buy some appropriate sized mandrel bent pipe and do it. Stainless is expensive and good. Common steel is easily gotten, but after building it should be ceramic coated to avoid rust.

 

The Mikuni 33 and 36 pumper had been the standby for the KLX300. Even though the 33 pumper is a mm smaller than the OEM CV34mm, it had superior flow because of the smoothbore design, not to mention the pumper benefit. BBlue's bored out 33 Mikuni just added another option, but honestly if you have a 300 or bigger, the 36 pumper is really the best option. Here was some good info on KLX aftermarket carbs which also included a Keihin FCR.

KLX Hop-Ups -- PUMPER CARBS