The RC390’s day on the dyno was an interesting one, with both good, and not so good outcomes .
The numbers we’re talking about are tiny here really, some may say comical/pathetic, particualy if you present them as £ per bhp, but what was interesting for me was comparing this one with my last slightly later (2017 Duke v 2016 RC ) 390 which I kept completely standard in terms of intake and exhaust.
As well as the comparisons with my old one, the boys here had also done another RC390 a month or two after my Duke and that one had a full de-cat system and they installed and custom mapped a PowerCommander on it, so I got that trace added to my before and afters for comparison .
Bottom line is that this bike (my RC390) is very slightly (~1 hp) down on peak power over my 2017 Duke and the other RC390 they mapped , but massively (relative term) stronger in the mid-range than either of them.
By massively, I mean approx. 5hp and 5ft/lbs – those numbers sound small, but believe me it’s significant when peaks you have are approx. 40hp and 25ft/lb.
The Powertronics and custom map made my old 390 feel more like my 525 in the middle, and this one now has some 20-25% more between 4k-6.5k than that one so it will be lively mid-range and will be a massively better road bike.
The road isn't really where this one is going to spend much of it's time though, and it's a shame the open airbox and Tyga exhaust doesn’t add any peak ( in fact this one was approx. 1hp down on my last one , but being realistic, that sort of difference can be down to so many things its not significant) , but that was probably an unrealistic wish on my part, and although on track I don’t anticipate spending much time in the mid rev-range, I’m sure there will be times when it’s of benefit.
Anyway, that’s the good stuff.
The not so good stuff is that this one likes a bit of a drink- of oil that is
It was on the dyno for about 5hrs in total and did a lot of runs, probably 50 or so, and drank 250-300ml of oil in the process- that's from top of sight glass to the bottom, and a lot on a relatively small single that only holds about 1.5l.
It’s got good compression ring sealin, as witnessed by the decent power we got, and no visible smoke under load , but coming back onto the throttle after shutting off would give us a stinky blue haze in the air.
Keith, my dyno man’s theory is that he doesn't think it's got any piston or valve damage (it’s done 900 miles in total) and the issue most likely stems from having “ too good” put oil in it when new, and been nursed too much in the running in period, with the result tht the oil control ring isn’t sealing as well as it should.
According to him Yams are prone to it, and R6s are particularly so if treated too gentle when new. My 390 Duke didn’t use a drop in my 2k-odd miles of ownership, and that was ridden flat out everywhere from day one so maybe there is some merit in that theory.
Anyway, we shall see. My plan is toplay it by ear for the first trackday or two, keeping an eye on the oil level, and if I think it’s a problem, the engine will come out and I’ll whip the top off for investigation, and assuming there is no damage in there, it’ll get a new set of rings ( and a bore hone if relevant, not sure if theses are chrome), follwed by my version of running an engine in
So the graphs:
This one is the hp before and after- less than 1hp increase at peak, but a healthy 10% or so increase all the way from approx. 5.5 to 8k, which is worth having and will definitely be felt.
These two show the final hp and torque graphs with baffles in and out (green & blue) compared against the Power commander equipped RC390 (red) they mapped, the curves of which just about identically match my post-tune 390 Duke.
What the AF traces on these two graphs also show is how much finer they can map with a PC5 than they can with the Powertronics unit, as you get 250 rpm increments on the PC5, compared to 1000 rpm on the PT, and that allows you to get a lovely, much smoother A/F trace than you can with the Powertronics unit.
But that doesn't really affect things too much in riding experience swings and roundabouts- the Powertronics scores in other areas- you can create custom ignition advance maps, vary rev limiter and alter quite a few other parameters that Dynojet don’t give you access to- not that important or relevant on a standard engine, but once you start playing around with compression ratios, cam timing etc
And this is the before and after roll-on, which going from what it was and those of my 390 Duke, look very healthy- should be a wheelie monster!
So, the upshot is we have a nicely mapped engine and a good base to work from- I’m going to change the oil (it came with what looked like pretty fresh 300V in it, so I haven’t changed it yet ) and whack some semi-synth in there, rag it around the roads a bit over the next few weeks assuming the weather stays reasonable, and I think I’ll book onto an April trackday at Bedford and see where we go from there before I make any decisions about pulling the engine to bits.
Will keep you posted...
I had a GPz305 which can't have put out any more than 30hp and I saw an (indicated) ton on that - not for vey long and a tailwind and loooooooong stretch of empty dual carriageway may have been required
) today around the roads of Buckinghamshire
in fairness to the poor little thing, that's probably more due to the other bikes I've been riding recently and my expectations- it was still easy enough to get 90+ up on the relatively short stretches I had it on, but a tarmac ripper it ain't and I'm gonna get absolutely mullered on that hill up to North Bend on Saturday, so some rude braking and stuffing up the inside might be on the cards 
)
