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ST4S: New owner with various frustrations

6K views 35 replies 14 participants last post by  tonered 
From my recollection the discs should be 5mm with a min of 4.5 mm so they probably need replacing anyway , pulsing , or not.

Does the engine run rough when revved high in a low gear ?
It could be wheel imbalance occuring at higher speeds.
Otherwise it probably just needs a good service TPS/Throttle balance to sort , it should be smooth...
 
The discs are pretty new but are 4.0 mm discs rather than the correct 5.0 mm items. I'm assuming this is not ideal but I guess OK as that is what the earlier bikes ran.

Its not wheel balance as its smooth on part throttle but gets rough as I wind the throttle on. Thanks for confirming that it should run smooth. Hopefully a throttle balance etc will sort it. The plan is to strip out the suspension etc over the winter so I'll do the valves etc then.

Keith
My workshop manual for my 2002 gives 5 mm disc thickness , cant say I know about the previous thin ones but 4mm seesm very thin as a starting point ?

My 2005 bike runs happilly ndown to 2500 provided only part throttle , its so good I have not kept the PC3 installed on it that I had from my 2002 bike even though I had it custom mapped (The PC3 did not make a significant difference to this bike whereas the improvement on the 200e engine was plainly noticeable)
 
Yeah, I meant earlier Ducatis in general. My 888 had 4.0 mm discs as well on what seems to be the same calipers and that braked pretty good.

Keith
Something new learned every day :)
 
"So, do I go with the Chinese discs or try and track down a good second hand pair? I dont see why I should pay a vast premium for Brembo discs when they seem to warp so readily on this bike!"

Quality may be suspect on the Chinese but seriously , I doubt your discs are warped , try as Mark suggests , cleaning the bobbins. I put a long bolt through each one and secured with a nut then attached a cordless drill and sprayed with brake cleaner whilst spinning an the muck that came out was amazing...

If you look for SH discs in spec , what guarantee will you have that you dont just inherit the same problem ?

If you decide to replace any way try Galfer they are a bit cheaper once you include the pads (often sold as a discounted package). I have them and although I dont particularly like the 'feel/action' of the pads the disc quality is good.
 
Keith , seems you have checked all the normal likely culprits , and as Sherlock says "Once you have exluded every alternative possibility , what is left must be the answer"
So warped discs it is then :)
 
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