Why work in progress you ask. Because it’s my new baby.

My toy of the moment is an ’89 model 851. The first of the red ( real? ) 851’s, not that the tricolours aren’t real 851’s, they are just too wacky and rare to really count. Bet that upsets some people. Send your complaints to the company address and see if anyone else here cares.

Bought cheap with 57,000 km on the clock, the engine is surprising smooth and tight. I can’t really comment as the only time I have ridden it was on the dyno for the runs seen below ( broken arm and leg again ). The suspension is not surprisingly stuffed, although many would say that it left the Marzocchi factory that way. Very easily fixed, however, with some careful rebuilding and the fitment of Ohlins as appropriate. With a little general tidying up, it should be a very nice thing.

Below is a power curve in its ‘as purchased’ condition. At this point it has some standard mufflers that have been got at in a fairly wacky fashion, no airbox lid and a chip that Duane can’t even remember making. As a comparison, there is also a curve of a std 916 with termi mufflers. Although the curves are plotted against road speed, the gearing is almost identical. The 851 is red, the 916 blue.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

The main differences between the two are : engine size ( 92 x 64 vs 94 x 66 ), valve size ( 32/28 vs 33/29 ) and exhaust size and style. The first 75 mm of the 916 system is much better than the 851, and the system is a little larger. How much I don’t exactly know. Probably 45 mm vs the 851’s 42 mm. The cams are the same. The 916 airbox and air entry are also markedly better than the 851.

Future plans include a standard baseline setup and then some cam timing playing, better exhaust, better air feed, lightweight flywheel and maybe investigate some more comp for the std engine.

There may also be a 984 cc ( 68 mm ( 900 SS ) crank and 96 mm ( 955 ) cylinders ) engine in late model crankcases in the planning. With some extra big valves, cams, good comp and lots of light weight bits, I am hoping for some serious hp. I’ll see how much free or cheap stuff I can dig up, as I don’t really have the $10,000 it would probably end up costing to buy all the required bits.

Here’s hoping.

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