st4s cases

[fastcan]

Hi there.
I have an st4s engine that I aquired. My thoughts were to use it as a spare for my sbk, but I have since heard that the cases are infamous for breakage.
My question is ... would I be nuts to hack up a good set of cases? To put in the sbk, I would have to machine the cases at the swingarm pivot.
Thanks for any insight.

[mw0dbb]

Depends what year it is? I have the 2002 st4s and the main bearings have been the big issue! I did notice during the rebuild though that there is some differences with the st4s maintenance manual? The is no mention of the special bolt in the engine, only place I could find it was on the 996SPS manual?

Anyway hope this helps!

John

[Puffin64]

That depends on what your SBK is, is it the 996 your referring too?
Is your question about the SSSA fitting to the cases, as opposed to the ST4S double sided swingarm?

[SS904]

If your talking about the engine case breaking at the rear mount, that has been more to do with the ST3 and possibly the 1000DS engines which apparently use the same lower end. Not much of an issue with the 4V bikes as far as I know, excluding the occasional damage due to overloading and / or not keeping the rear mount tight...

There are more differences than the swing arm pivot spacing between the ST4s and a 996 SBK engines. Heads and intake cams to mention the two other obvious differences. Not sure it's worth the effort to make that swap. You'd be better off selling the unmolested ST4s engine and picking up and actual SBK engine, which surly must be in greater supply than a rather unique (comparatively) ST4s mill. You'd probably come out ahead money wise.

[MarkST]

Originally Posted by fastcan

Hi there.
I have an st4s engine that I aquired. My thoughts were to use it as a spare for my sbk, but I have since heard that the cases are infamous for breakage.

Lots of 851/888 specials are built using ST cases, because quite the opposite is true.

[Sportyeric]

At risk of hijacking the thread, do I understand that overloading the bike, weight-wise,can cause the cases to crack? Or is that over-tightening the rear mount?
And then on-thread: if you decide that using an ST4s engine in your frame is not the best idea, I would consider the merits of keeping it in Canada, depending on its value. All this talk of weak main-bearings is making me nervous about my new-to-me ride.

[MarkST]

Originally Posted by fastcan

My question is ... would I be nuts to hack up a good set of cases?

I'd have to agree that yes this would be rather nuts.

Originally Posted by fastcan

To put in the sbk, I would have to machine the cases at the swingarm pivot.

To me, logic dictates that this operation within itself will weaken the cases.

SBK cases for SBK's.
ST cases for ST's, Monsters, and 851/888's.

[mbevans]

In seeing more than a few SBK 748/916/996 motors apart in my time and speaking with a couple of respected Ducati engine builders here in the USA, there has been many 996 SBK engines found at the wreckers destined to be used for race/track motors that had suspect main bearings, heck I had one, a 2001 996 SBK motor, yes new bearings @ 15k miles for that girl...

There have been documented many ST4s motors that have reached in excess of 50k miles with NO bearing issues.

And of course there have been a few ST owners that have had faulty bearings, or faulty set-up bottom ends from the factory.

While yes I will be pissed if my 2002 ST4s motor plays the main bearing issue, but we roll the dice sometimes owning our Ducs.

IMHO I’d say if you can machine the engine bosses and make it fit, then rebuild and enjoy it any Ducati…

But then again I’m a recycler..

[MarkST]

Originally Posted by mbevans

IMHO I’d say if you can machine the engine bosses and make it fit, then rebuild and enjoy it any Ducati…

Upon giving the matter more thought, and looking at many pictures of both the ST4 and standard 916 cases, I have to retract part of my previous post and agree with this - it seems that the extra width of the ST cases is in fact simply a larger boss that just isn't there on the 748/916/996 cases.
Go for it, but make sure to post pics of the machining process if you can please.

Originally Posted by mbevans

But then again I’m a recycler..

Top man, so am I

As a side note re the main bearing issue, I posted a pic on another thread of a 916 that was at a meet I organised in the summer that had 140,000 miles on it. The bearings had gone on it, but at 120,000 miles. Post #60 here - 2002 ST4S Whining noise??

[fastcan]

thanks for all of the input.
I think I will shove it in the corner for now.
Decisions...