Classic Motorcycle Mechanics


If you really want a Ducati 748, what should you be looking out for and how much will you pay? Rich has the answers…


What to check for if you’re wanting a Ducati 748.

With this month’s Retro-spective star being the baby brother of the 916, we asked Louigi Moto’s Rich Llewellin, who’s been a Ducati expert for more than 20 years, for the lowdown on this mini L-twin from Bologna.

“Buying, using and maintainin­g the 748 Ducati should be fun, but they do have their quirks,” he says. “Early ‘two yellow wire’ alternator models 748 Biposto, SP and SPS have trouble with the plug at the end of the alternator wires. It tends to melt. Early reg/recs went up in smoke due to overheatin­g and the bodies need to be earthed (they are often left off and put on the battery.) Bigger connectors and a later reg/rectifier should cure this issue.

“The front timing belt tensioner pulley is only just large enough to get the tension correct with a new belt; a worn belt makes adjustment Impossible, but a larger pulley can sort this. Adjuster pulleys can only be adjusted anti-clockwise or the belts will foul and have a very short service life! All early belt failures were caused by the mechanic adjusting the belt the wrong way; there was never a problem with the belt itself and people were reassured when the new Kevlar belt was introduced, but it was just lack of training.

“The rear sprocket carrier has a large circlip on the hub bearing side that holds the sprocket together. The groove wears and recedes over time and this in turn makes the sprocket rub against the chain adjuster hub. Another issue in this area is the cush-drive rubbers, which delaminate and the outer ring backs out and mills away at the chain adjuster hub. Early models had a recall for cracks in the rear axle, but I’ve never seen one do this.

“The rear brake lever on the early model didn’t have a return spring and they were susceptibl­e to binding and locking the rear wheel up while riding. Side-stands used to fall off due to not being thread-locked and Ducati were a bit sparse on the same product regarding the alternator locknut, so it’s quite common for these to come adrift.

“Early fuel tanks had no internal coating and when the breather blocked or water got into the tank, it would rust from the inside out. The SPS model is possibly the rarest model and the least reliable in the family as the quarter crank and titanium con-rods were way out of balance when they left the factory. Some only lasted a few thousand miles before one of the big-end shells destroyed the crankshaft. The high-revving nature of this little pocket rocket often led to its early demise, especially on the removal of the camshafts and finding the chrome flaking off the opening rocker arms. Early diagnosis of this is small fragments of chrome in the oil.

“The 748 came from the factory with a

60 profile front tyre to make it feel different to the 916. This I think did it no favours in the handling stakes. When changed for the 70 profile (à la 916) the machine handled better.

“In my opinion, the later ‘three yellow wire’ alternator machines were more reliable; this included the 748 Biposto and S, 748E and 748R. That back brake now had a return spring, the rear hub issue was solved with a new flange and large washer instead of the circlip: but the cush-drive rubbers still came out!

“The alternator had been upgraded to the three wire job and was less prone to melting (but sometimes still did!). Larger pulleys on the belt tensioner took care of the belt problem. Crank balance was still an issue and a number of crank failures alongside corrosion problems/issues saw a rapid devaluatio­n of the model, along with the sheer cost of rebuilding the motors.

“Getting the motors out of corroded machines saw the swingarm pin seize In the left-hand bearing bush and many have had to have been cut apart. The opening rocker arm wear was still a problem (if not worse), but fuel tanks now had a coating on the inside, but the factory missed out the welded flange, so the problem still existed!

“Even on later bikes with the modified crankshaft, the alternator nuts were still coming adrift and the oil sludge bung was winding itself out, so it would fall out, resulting in loss of oil pressure and the crank would seize. Early warnings of this were fingernail-size cuttings of aluminium in the oil.

“The 748E was just a cheapening exercise and had the non-adjustable headstock, but actually was the best handling of all 748s in my opinion, even if the non-quick release fuel tank made servicing a pain. The daddy of the roadgoing 748s was the R: early ones had Showa forks and the later Ohlins forks.

“Service life on the engines for the R are short due to the ‘even lighter than the SPS’ quarter crank with titanium con-rods. Crank balance was also an issue on some bikes, causing premature failure. Timing belts are unique for this model and are wider than all the others in the range. Also unique is the fuel-injection system, and set up is critical for this. Studying the fuel and ignition map binary shows a very low fuel delivery and small Ignition advance at idle. With a modified EPROM Chip this can be eliminated and the machine able to tick-over under its own accord, most having a poor or non-existent Idle. Despite the issues, find a loved 748 and It will reward you with many miles of smiles.”

With a production life that spanned almost a decade, there are plenty out there. The first Bip model’s rrp was £10,000 and the later base model ‘E’ was around £8300 at the end of the 1990s. Top-spec SP and R models came in at around £11,000£12,000 – and that was 916 territory. In the used market, £3000 gets you a used and abused model, while early SPS start at around £7000 and can rise to £15,000 for low-mile late model Rs.

 ??  ??
 ??  ??
 ??  ??
 ??  ??
 ??  ??
 ??  ??
 ??  ??

Newspapers in English

Newspapers from United Kingdom