Read be­fore go­ing 851 crazy

Practical Sportsbikes (UK) - - Ducati 851 888 -

En­gine

With reg­u­lar ser­vic­ing the en­gine is re­li­able, al­though it doesn’t take much to make it a po­ten­tial mine­field. Lis­ten for a squeak when start­ing which might in­di­cate the sprag clutch is slip­ping.also check the al­ter­na­tor nut has been tight­ened and that valve clear­ances have been in­spected ev­ery 6000 miles.

Cam belts

The weak­est point on the en­gine. Check the ten­sion and con­di­tion reg­u­larly. Re­place ev­ery 5-7000 miles or at the first sign of wear.

Head gas­kets

All eight-valve head gas­kets sup­plied now are a metal type and ap­prox­i­mately 0.5mm thick, while the early 851s used a com­pos­ite type that was 1.1mm thick.there­fore, if you’re re­plac­ing an old-type gas­ket you must also re­place the base shim with a thicker one to com­pen­sate.

Cor­ro­sion/wear

By def­i­ni­tion any 851 is now over 25 years old and, be­ing Ital­ian of that era, cor­ro­sion and/or wear can be an is­sue. En­gine paint is prone to flak­ing off, thet­ri­col­ore’s orig­i­nal iron discs rust, plas­tics crack and paint wears. In­spect very care­fully.

Reg­u­la­tor/rec­ti­fier

A weak spot as with many bikes, and has a bit of a habit of burn­ing out. Needs to be swapped for a mod­ern unit if it’s not been done al­ready.

Weak han­dle­bar clamps

Doesn’t af­fect all bikes but worth check­ing – more than a few have one in­ef­fec­tive clamp bolt due to a failed weld. Check that both bolts are tight.

Wheel align­ment

Of­ten in­ac­cu­rate due to poor de­sign of the spin­dle plates which can bend or twist when tight­en­ing the axle, thereby giv­ing pos­si­bly in­ac­cu­rate wheel align­ment. If in doubt, use a tape mea­sure to check the swingarm-spindleto-wheel-spin­dle dis­tance on both sides.

Wheel spacer

A spacer on the chain side is of­ten fit­ted in­cor­rectly, if at all.ta­pered in sec­tion, the ta­pered bit goes to­wards the wheel with the flat face against the swingarm. Fit­ted wrong, the spacer in­ter­feres with the cir­clip in the sprocket hub which makes the wheel very hard to turn. Leave it out and the sprocket car­rier face in­ter­feres with the swingarm, dam­ag­ing both. Def­i­nitely worth check­ing.

Bat­tery

An up­rated bat­tery is rec­om­mended to pro­tect the sprag clutch and is a com­mon mod, but re­quires a dif­fer­ent mount­ing plate.

Wiring

The 851’s wiring har­ness is pretty tough but the con­nec­tors are sus­cep­ti­ble to wa­ter and, thus, cor­ro­sion. Check for loose or frayed wiring and cor­roded con­nec­tors. Cor­roded con­nec­tors be­tween the gen­er­a­tor and reg/rec can cause blown reg­u­la­tors.

Wheels

The three-spoke alu­minium Brembo wheels fit­ted from 1989 are slightly soft and prone to dis­tor­tion if rid­den over pot­holes. Check that they run straight and true with both wheels on a stand.

Clutch

The dry clutch of the 851 was de­signed pri­mar­ily for rac­ing and is a lit­tle del­i­cate for pro­longed use around town, for ex­am­ple. A noisy rat­tle from a dry clutch is nor­mal, es­pe­cially when sta­tion­ary, but if it’s ex­ces­sive and con­tin­ues when on the move then the plates will need to be re­placed.

Con­tacts

ducati851and888.com

du­cati.ms

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