RSVR ’07 Playing With Air box Stuff - Written 06/08

Summary: RSVR’07 model demo run all std, with Remus slip on mufflers and then with flapper disabled, air box lid removed and inlet trumpets extended.

I got to have a quick play with our second demo RSVR.  I was intending to go further, but as often happens with demo bikes, it got sold.  So no cam timing changes or other tuning.

First up is a graph of this bike all std and with Remus slip on mufflers and ECU mapping set to engine variant 2, shown against the previous demo RSVR with the same set up.  Green is this bike before, red after.  Previous demo before is blue, after yellow.  You can see this bike was better all std and not as good with mufflers as the previous one.  You get that.  The after results are pretty consistant though, especially the air/fuel curves shown in the second graph.

After the red run shown above I crimped and unhooked the flapper valve vacuum line to keep the flapper valve in the inlet tract behind the headlights open.  I wasn’t sure if it had any influence at WOT, so this was just a simple test to see.  As shown below, it didn’t.  After a couple of runs like that I lifted the tank, removed the previously unscrewed air box lid and dropped the tank again.  The graphs below show the result.

Green is Remus slip on mufflers (the red curve from the above graphs), red is the flapper valve in the open position and blue is with the air box lid removed.  I’m a little surprised that removing the air box lid hurt the peak power and richened the mixture in a couple of places, but it was a consistant result over a couple of runs.  Although I doubt you’d notice it on the road, and you might just notice the improved mid range.

Power first, then torque and air/fuel.

After these runs I shut it off, removed the air box and fitted some extensions I’d made for the inlet trumpets.  These were just 30mm long alloy tubes machined to 57mm ID and some spacers with longer screws to hold them in.  This effectively mimics the Tuono trumpets which are 30mm longer than the RSVR trumpets.  The result was a little better than I expected, as I had expected a top end loss of some sort.  Other dyno results I have seen elsewhere for this mod have shown a small top end loss.  Given this result I’d be tempted to go maybe 15 or 20mm longer again – it certainly couldn’t hurt, as the power is the same, just peaking 400 RPM lower.  Green is std 20mm long trumpets, red is with 30mm extensions.  Power first, then torque and air/fuel.

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