[Ducati] 999 compression figures?

[DesmoBob in Paradise]

Thanks Rich. I'll use that 14.7 factor until someone can give me a shop spec. This yields a theoretical ceiling of mid-high 160 psi range.
I'm not so much doing a leak down per se, but just seeing if I'm in spec.

ULTIMATELY I'm trying to diagnose a chronic starting problem. First thing I ruled out was electrics & charging.
Got spark, got fuel.
Beginning to think it's something more serious. Like a bad valve seal. Or aftermath of an improper break-in. Or wrong ECU (long story).
I had prepared a long post with all the symptoms & notes, but it's on another hard drive at the moment.
I've pretty much exhausted my troubleshooting agenda, now I'm just taking shots in the dark.
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DesmoBob in Paradise


> Date: Tue, 25 Sep 2007 16:30:28 -0700
> From: bigredxrunner at yahoo.com
> Subject: Re: [Ducati] 999 compression figures?
> To: ducati at ducati.net
> 
> I guess the range is to take into account leaks??? I used to think a good rule of thumb was CR times 14.7 psi, since the CR is a ratio of  bdc to tdc volumes and you should be filling with 14.7. But this was always a theoretical maximum I think and does not take into account the practical difficulty of getting an exact number without actually measuring volumes and then taking into account leaks at valves, seals and rings...or the difficulty of filling and holding at TDC. I take it you are doing a leak down test?  The other isue i ahve found is the typically poor leakdowns that do not seem to effect hp much. You know a Ducati really does depend on compression for valve sealing I think whereas a lot of motors have those pesky springs. When ding a leak down you do not have benefit of the substantial pressure of combustion, air just aint the same for sealing and the rings really do nto work so well with those measly pressures used for leakdown testing with
>  air.  Truth be told the differences are not so great, should be able to look in shop manual for numbers, I guess that is what you are hoping someone will provide. Rich
> 
> ----- Original Message ----
> From: DesmoBob in Paradise <d3smob0b at hotmail.com>
> Subject: [Ducati] 999 compression figures?
> 
> Does anyone know the recommended cylinder compression for a 2003 999?
> 
> I have the factory manual for a 2006 749, but I imagine the figures for a 
> 999 would be different. For the 749, it says 9-11 bar (131-160 psi).

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