Thursday, February 21, 2013

888SP4 vs 748/853 Dyno chart

Today I ran an 888SP4 on the dyno, the first of the old school hotties I've run on the new Dynobike dyno.  The runs I had on the old dyno, compared to my 888, showed that the SP motors (pre SP5 anyway) really weren't anything flash power wise.  So I compared today's bike with the 853 kitted 748's I've done recently.  They've been 748 with 853 kits, modified combustion chambers and std ports.  Pretty basic.  Blue is 888SP4 with 98/102 cam timing and an eprom sort of to suit ("in progress" runs) and red is 748/853 with 111/108 cam timing and eprom to suit. 

There is the possibility that the 748's more powerful 1.6M ecu (with offset mapping for cylinder 2) allows it a little more power compared to the P7 running the 888 which only has one map for both cylinders.  Plus the 748/853 will have more compression.  And slightly smaller ports, which seem to work nicely at this capacity.

The 748/853 is certainly a nicer engine to ride, but 36 degrees less cam duration will do that.

Saturday, February 16, 2013

750 Dry clutch photo

A photo for a Monster forum question.  750 dry clutch, used on the 750 motor from 1985 750F1 to 1992 750SS and the 1988 851 Tricolore, early 906 Paso and 1990 900SS.


Friday, February 8, 2013

More on inlet trumpets

A bit heavier going (haven't read it myself yet), but some more serious theory on inlet trumpet design

Ok, so now I've read it.  It's very interesting, for both its content and, in a somewhat typical way, as to how much change there sometimes isn't when you move from a functional, but simple solution to a more complicated solution.  ie, plain pipe to simple radius and then elliptical form.  Certainly, the reality of manufacturing an accurate elliptical form as opposed to a rolled edge contrasts strongly against the minimal improvement it offers.  And, of course, when you're playing for sheep stations, not having that 1.5% is getting your arse kicked.

Space is also a consideration when you have trumpets close together.  ie, Aprilia 990 motors, where oversized inlet trumpets need to be squared where they meet.  Although I have been told that fiting large entry, "elliptical style" profile trumpets makes a noticeable difference to engine output.

Looking at the profiles again in figure 5 and remembering what I was pulling apart yesterday, simple radius is 851/888 and aerofoil/elliptical is 916, etc.  So I guess Ducati figured there was something in it.

And if you bought trumpets from someone like TPO or WASP or Ducshop you'd find they're large entry, probably elliptical and definitely short and fat.

As a side note, Professor Gordon Blair is a real two stroke expert, and has spent many years at Queens' University in Belfast.  He has done lots and lots of very cool stuff over the years. 

Thursday, February 7, 2013

Varying intake trumpet length and effects thereof.

The following page was linked into a thread on the Supersport page of Ducati MS and it's just too good to not try to bring more attention to.  Some may see that it's car based and turn off, but that's irrelevant.  It's great general info, and the kind that hopefully will convince some reading it to apply and expand on.  Or just to think outside the box that most others live in.  Hopefully you'll find it as interesting as I did.  The part throttle info is particularly useful too.

Many thanks to Dave @ EmeraldM3D for the effort and posting the results.

Tuesday, February 5, 2013

Phil Aynsley's photos from the Island Classic


The Island Classic and Ago

I went down to the Island Classic for the Saturday to fiddle as required with the MV Agusta Julian McLean had built by Albert Bold, which was doing demo laps ridden by Ago.

Julian is the man from Tahbilk Winery who has been a driving force behind the MV Agusta presence at any motorcycle related function in Victoria for the last 12 or so years.  An passionate enthusiast of the type small volume importer's dream about, he also puts his money where his mouth is.  Hence the bike built by Albert.  It's a Magni frame with a 600 engine taken out to 887cc, dry clutch and chain drive conversions and original MV race team plasma sprayed aluminium front discs.  Albert is a very high end machinist, and the titanium throttle linkages, for example, are just a work of art.  The bike was featured in the December issue of Motorcycle Trader (Au).  100hp with the megaphones and 155kg.  It's a pretty impressive piece of old kit just in itself.  Here's a link to Albert's previous MV race bike

Ago turned up in a Fiat 500 with a local lady named Rosa and from the moment he arrived was swamped.  He did a couple of sessions both days and the bike went well enough that only a gear lever adjustment was required.

So, to some photos and video.

Julian firing it for the first time on Saturday morning I believe.  Rosa in the background and me being the only one smart enough to put their fingers in their ears.  Of course, Julian has earplugs.  It is godawfully loud.  Albert made a 4-1 exhaust for it as well, which made an extra 15hp.  Just not old school cool.

I like this photo.  Ago in ungracious pose fiddling with boot, me watching on for no apparant reason, photographer extraordinaire Phil Aynsley with the big camera and high vis, Tony Hannagan from Beveltech (Phil's pack horse for the weekend) with little camera and high vis, unknown paramedic.  Note to self, pack high vis for next time.

Julian warming it up for Ago, smile hiding the paranoia of hoping like hell nothing goes wrong. 
A very short video of Ago down the front straight.  First movie with my iPhone, didn't work out quite as planned (kept pressing in the wrong spot).  You get the sound though.  Strangely, not as loud as it goes past as I expected.
There's a much better (longer) video on the AMCN facebook page, I just can't get it to link.