— Ducati ST3 Cam Timing Changes and tuning with Techlusion/SFI

2 Апр 2015 | Author: | Комментарии к записи — Ducati ST3 Cam Timing Changes and tuning with Techlusion/SFI отключены
Ducati ST3

ST3 Cam Timing Changes and tuning Techlusion/SFI — Written Feb

Updated June ’06. Std cam results added at bottom.

We a demo ST3 that’s got quite a few km on it now so I I’d have a play it some more. In the previous ST3 I did the usual muffler/airbox/fuel thing to see was in it. One thing that I noticed those curves — the mufflers and air filter kit” in — was that the power flat around 8,000 RPM and pretty much at that 10,000 RPM.

To me, that indicates something is restricting the while everything else is to keep going.

The ST2 also does this, in its going flat from to 9,000 RPM. My ST2, its ported heads, better valves and shorter cams more lift, had a shape like you’d expect a 2V in particular) with a smooth to a rounded peak, falling off there.

From my experience bigger exhausts on the ST2 and the 851/888 restricted doesn’t show as a power curve — all bikes have had power that peak and fall and an exhaust that makes power simply raises the and the fall also.

And given the ST3 has the same airbox as the ST4 and 4S and its throttle bodies with the 748/888/916/996 range since it certainly isn’t inlet

So I tend to interpret the flat curve as over-cammed or under-valved. is sort of the same thing, on the specifics of the model. The cams in the ST3 are of late Ducati cams being short duration degrees inlet, 259 exhaust) and lift (10.7mm inlet, exhaust) so it certainly isn’t In fact I’d say it’s well cammed for the set rev limit RPM).

It’s certainly under-valved 2 34mm inlet valves it has a touch more valve than a 916 (33mm inlet and less than the 4V engines of the capacity (36mm inlet Exhaust wise the 40mm is sort of equivalent to two 28mm again too small. Plus it has header pipes, which I cost peak power on any 4V.

Ducati ST3

as much as I’d love to the heads and fit 36/42mm valves and a header set the management would be unimpressed with the capital so I just thought I’d with the cam timing to see what to the curve with some The other side of the flat curve thing is that you can sacrifice some of the higher RPM for more roundness lower And so we did.

Checking the cam timing bore a result to the S2R I’ve checked You’d think with the pullies every model in the wears these days have the ‘as delivered’ somewhat under control. not so. The spec on the ST3 gives a calculated centreline of 114 degrees.

On this bike the ‘as settings were 117 degrees on the and 123 degrees on the exhaust — 3 and 9 retarded.

I took the opportunity to the piston to valve clearance, of there was quite a bit, so I to advance the cams while I was to 107 degree inlet centreline. to se what would happen, you never find out if you don’t This gave the following specs.

Note: I don’t check the exhausts given on the same cam, working off the inlet profile, so the exhaust are just calculated. All timing was with belts at the running of 142Hz on the Mathesis twangometer.

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