The 748 had/has a few problem areas that if sorted out will provide a bike that will give you years of grins.
Some of these problems are exacerbated on the 748 as it revs higher than the 996 of the same era. When looking at a 748 try to ascertain that these issues have been sorted by previous owners.
Flywheel nuts were a problem. Poor vendor quality and arguably Ducati quality control had nuts that would loosen. If not caught, the flywheel and perhaps the crank could be trashed. A cheap preventative fix for about $30.
A large batch of poor quality rocker arms were purchased from a vendor and installed in thousands of 748 and 996 bikes. These had chrome plating that will flake. Big $$$ to fix. For a while Ducati had a "gee we're sorry here are your new parts for cheap" program but that ended a few years ago.
All the older sbk's, 916, 748, 996 had single phase charging systems until (don't quote me) 2001?
This charging system was marginal at best. The typical failure was a lot of smoked regulators. You'll see a lot of threads about always keeping my 748-996 on a battery tender when not being ridden. Relocating the regulator to a cooler location and wiring in good condition solves this issue.
The 998 is essentially the same vehicle as the 748. Upgraded bits here and there but it has two notable areas that were good improvements.
The engine has the newer Testastretta top end which is bulletproof. Easier to service and no rocker arm issues.
The 3 phase charging system is first rate. A 'Stretta bike can sit for months and the battery will still be 100%.
I have a 998 with 20,000 miles. The only true failures have been the high beam relay $4 and the coolant expansion tank $45. (same part as the 916, 748, 996) The 998 is generally a push the button and ride it kind of bike.
As a note when looking at a Duc or about 50% of the brands for that matter is a simple check on the electrics. I noticed the problem on mine a couple years ago as it was sluggish to start.
Many manufacturers use a Shindengen or Hitachi regulator/rectifier. These use a crappy connector on the stator wires. (the three yellow wires) This connector has been used for almost 30 years and problematic on Hondas, Yams etc. It will gain resistance with time, heat up and melt. No charging will likely leave you stranded as the battery goes flat. Cut this connector off and join the yellow wires. Problem averted. My buddy's Aprilia smoked it a few months ago and he juuust made it home and the engine quit.
Don't sit there, buy one! You'll quickly find out that a Duc is all about the chassis. You'll understand after 500 miles what stability is all about.
