That funny looking thing in the exhaust pipes right under the engine - i suspected it was some sort of catalytic convertor, but i just read about HTEV, Honda Titanium Exhaust Valve - which regulates backpressure for optimal midrange torque, and goes wide open at 7000rpm on the RR

 

pic is from http://www.rrzone.com which looks like a good 900/929/954 site.

 

wow honda's always thinking

 

yep, that what it is. Some dont like it though. There are all sorts of wierd flappers that open at speed on that bike

 

i suspect the spincter closes tight at WOT.

 

Yamaha has been using a system like that since the 80's (EXUP) so it's really nothing new - I don't know why Honda just doesn't start using VTEC (as well as the exhaust valve..) It would kick ***! Come on honda!!

 

you are correct, the exhaust valve is not a new concept.

Honda used VTEC in the 80s on small racebikes, and a variation of it can be found on this year's VFR Intercepter V4 engine.

 

Yeah, I know, but I wanna see a CBR600F4I-VTEC dagnabbit!!!!!

 

I'm not so sure the VFR VTEC is true VTEC or not...it has nothing at all to do with changing to a different cam profile a la the automotive VTEC. It runs on 2 valves/cylinder until 7000 RPM, at which point it opens the other 2. Theoretically this gives the low-end torque benefits of a 2-valve per cylinder motor, with the high-end breathing of a 4-valve. In real life it gives a nice little kick and feels good, but on the dyno it's not significantly different from the non-VTEC V4 motor. A nice idea though.

Oh well, I guess it's VTEC if Honda says so, right?

 

yeah i agree, thats why i said a 'variation' of it.

 

I think the regular VTEC might be kinda heavy.

 

I've also read in a bunch of magazines that they really aren't seeing that great of power gains with the VFR -vtec.

 

thats correct. if you read the rest of the article, you'll see that the vtec is only enhancing midrange torque by increasing intake port velocity, which translates to better filling of the cylinders at a given rpm.

 

Yup...Vtec isnt the answer with bikes as the increased mas offsets the gain. But as a road implement its fun. Dont forget that Yamaha were the first ones out with any kind of Variable timing in production, and still the kings of the 2 stroke hill, ladies and Gentlemen i present .........

Y P V S