Tuono ’06 model with Mufflers, etc - Written 10/07

Summary – Tuono all std and fitted with Akrapovic slip on mufflers, airbox inlet restrictor removed, K&N air filter and ECU map variant 2.

This Tuono, a customer’s bike, came in for a first service and some other stuff so we took the chance to do before and after runs.  One thing I was interested in was the airbox inlet restrictor, which I noticed on another Tuono we’d had in bits a few weeks before.  The RSV-R, with the flapper valve in the front fairing air duct, doesn’t have this restrictor, although both bikes share the same airbox otherwise.

The restrictor itself screws into the front of the airbox at the mouth of the box where it sits up against the back of the front fairing air duct opening in the main frame.  The opening of the airbox is probably (he guesses, wishing he’d taken measurements) 100mm square, whereas the hole in the restrictor is probably 60mm round and bell mouthed.  I had asked the question on the AF1 forum if anyone had some before and after experience with this mod.  Those who replied in general said maybe a bit more noise and more surging at low speed with no real performance increase.  I’d say it’s one of those things that looks bad, but in reality isn’t.  It may realistically simply be a noise lowering (and hence test passing) device – I don’t know.

The before run shown in green is all std Tuono, running the std ECU map variant 1 (meaning closed loop) and fitted with the supplied 15 tooth front sprocket.  The after run in red is with Akrapovic slip on mufflers, K&N air filter, airbox inlet restrictor removed (airbox otherwise original), ECU map variant 2 (open loop) and the idle mixture reset to 4.5 – 5% CO.  A very good improvement over std for a modern bike with simple mods, but I thought it’d make more peak power.  Power first, then torque and air/fuel.

Next I’ll compare this Tuono to our old demo RSV-R.  First up all std for both, Tuono in green, RSV-R red.  I’m not sure why the top end of the RSV-R is better – maybe the Tuono restrictor does hurt the very top end.

To the above graph we’ll add the Tuono as modded in blue and the RSV-R with Remus slip ons and ECU map variant 2 in yellow.  Again the curves are fairly similar, with the RSV-R having a top end advantage.  As above - no idea why.  Maybe the RSV-R front fairing air duct is bigger or better flowing.  Otherwise, they’re identical motors from airbox entry to exhaust tip.  I’m told the cam timing on the V990 motors can vary quite a bit, so maybe the inconsistency there is also having an influence in this comparison.

The owner had been riding this bike before the first service with the Akrapovic slip ons fitted, but otherwise std – airbox inlet restrictor fitted, std air filter and ECU map variant 1.  He felt there was quite a noticeable increase in performance and rideability with the above mods, always a good thing.

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