Trading the ZX-7R for a CBR929RR

[mechman600]

Yeah, not exactly eco compared to most other bikes here....

But unlike the 7, the 929 has some technology like EFI and HTEV. HTEV is an exhaust valve built into the headers that varies the effective length to the collector and increases backpressure at lower revs. It is broken on this bike, but parts are ordered, so we will see how it works compared to the "old fashioned" ZX-7R. It sure is a lot quicker - 150 HP and 380 lbs dry.

[renault_megane_dci]

So that is like Yamaha EXXUP system ?

It is just a matter of linking the exhaust flow with the inlet flow (AKA throttle) to get rid of a part of the camminess of those very high specific power engines.
I believe they can do the same with cam phasers these days but the trend might not have reached the bike world so far.

[mechman600]

Originally Posted by renault_megane_dci

So that is like Yamaha EXXUP system ?

It is just a matter of linking the exhaust flow with the inlet flow (AKA throttle) to get rid of a part of the camminess of those very high specific power engines.
I believe they can do the same with cam phasers these days but the trend might not have reached the bike world so far.

I believe the EXUP was simply a butterfly valve that created restriction at lower revs. This HTEV is more complex and, well, seems like it should work well.

IDLE to 3000 RPM:
Cylinders 1 & 2 are combined, cylinders 3 & 4 are combined in HTEV with only two outlets for back pressure:

3000 to 8000 RPM:
Flow straight through the HTEV. Cylinders 1 & 4 are combined, cylinders 2 & 3 are combined in the exhaust collector after HTEV (not pictured):

8000 RPM + (11500 RPM Redline):
Hard to tell by picture but it looks like all cylinders are combined in HTEV:


Honda has used actual for real VTEC in two bikes - the Japanese only CB400SF and VFR800F. Critics say the only thing it accomplished was added complexity. I rode a VFR800 version and it was kind of neat, but whether it was only the sound change at 6800 RPM that tricked my head or not I will never know. Not sure why it hasn't caught on - more expensive? Heavier? Higher chance of catastrophic failure if something goes off? Who knows.

[mechman600]

I finally got the HTEV system working. Turns out there was more than one problem with it. First off, the ECU had a bad driver, so there was no power to the HTEV servo motor. Secondly, there was a spread terminal at the ECU plug making poor contact on the +5 VDC HTEV position sensor wire.

It would have been mostly simple to fix, but my first used eBay ECU caused my bike to have no spark. I had to go through the resolution center to get a refund. The second used ECU caused my bike to run on three cylinders. I had to go through the resolution center again to get a refund on that one. Today I installed used ECU #3 and it works like a charm.

The engine definitely runs smoother under 3000 rpm. The EFI is calibrated to have some exhaust back pressure at low revs, so with my HTEV previously stuck in the 3000-8000 rpm position, the idle was much higher and hunted up and down, and the throttle was jerky under light loads.

It will be interesting to see how the FE is with this bike. I'm not expecting much with 929cc, but hey, you never know - it might be decent.

Here is a video of me testing the HTEV out:

http://www.youtube.com/watch?v=35hPF_-WQlo