2009 Honda's

[rgaede]

Think about it (directed to people who think the pipe is more exposed to damage), for how long had the two stroke pipes wrapped around the front of the engine? I know my 125s pipe coms a lot closer to the front wheel than that four stroke header.

[rgaede]

Screw the 450, check this out!
http://motocross.transworld.net/2008/09 ... dge-match/

[DJ99X]

Hahaha, thats sick. That was a nice whip he pulled with it

[frederick]

I guess that xr is Tedescos 09 sx bike

[lluks252]

That video was sick, XR's are a huge couch, when he was honking the horn that was hilarious, along with throwing the tweaked one hander.

I got my DIRTBIKE magazine w/ the 2009 honda CRF article...Honda added the all new 5th generation 450 chassis, completely different, the all-new 48mm Kayaba forks are said to be exclusive to Honda(for the 450, 250's already have KYB). It says the killswitch glows via LED readout. If there are problems with the EFI it blinks. The swingarm is 18mm longer, & wall thickness reduced from 3.75 to 3.0mm. Personally, I don't like the head pipe but the way they have it come out, looks like it can't get smashed by laying it down on either side, but who knows. The price of the HRC PGM-FI Setting Tool is $349. It has a shorter connecting rod, and new valve train. The cam is directly over the intake valves, but now the exhaust valves are operated by two more compact rocker arms rather than the old forked one. Looks sick, I can't wait to ride one.

I have the scoop on the 2009 YZ450F too I'll start a new thread for it.

[ShackAttack12]

You guys have two things wrong with the mechanics of the new technology.

First off, EFI does not consume more fuel.... it certainly can, but thats the beauty of it. The ability to tune an EFI system MUCH MORE EASILY than tuning a carb is one of the best aspects. Hook it up to a laptop, and mess with a 2d or 3d fuel map. The beauty of fuel injection vs carberation is that there really arent going to be any famous dead spots that you would see with carbs. You can set the right amount of fuel for each rpm and load and really extract the most amount of power out of the setup on any given day. Also, the bike can be tuned to the track much more easily.

Second.... on a 4 stroke single cylinder engine the length of the header really doesnt make much of a difference. Honda's reasoning for designing the header like that is to help move some of the weight more foward and down on the bike.

In a 4 cyl engine, long tube headers that go from 4 primaries into 1 collector do create a bit of a gain in high rpm horsepower, but at the expense of low end torque. This has to do with backpressure, and resonating exhaust pulses (more specifically, controlling the "suction" wave)

A 2 stroke bike is a difference story.... That huge buldge in the header is not there just for looks.... without being very technical, the buldge helps extract exhaust out of the cylinder due to resonating exhaust pulses.