Just finished playing around with with an 89 851, a bit of fun, another journey in its own right. Not quite to the level of one of Tolkien's characters dragging another from the mir into the light. But along the way the presence of a darker side seem to manifest it self in external equipment failures. Like the needle on the dial gauge after 10 years finally deciding that its relation ship with its drive shaft was over and it's time to move on. Literally. And being sneaky about it.
The extension on the compression gauge had similar ideas, except its feeble attempt at subterfuge were thwarted when it went for the good old go hide in a dark spot at the bottom of the spark plug well and hope nobody noticed. Magic red potion sorted its cunning plan. Woodruff keys from a far off land laying down webs of deception and lies in yet just another assault on the cleansing of the soul. Their true identities finally exposed and documented under the interrogation of the circle of life... and a new dial gauge.
And the soul did indeed need cleansing, an ethereal Matmos like entity had infiltrated the very essence of the bike. A freak, in a long forgotten quest in understanding and search for purity had escaped and found its way into the poor unsuspecting heart of the motor. A set of Brook Henry's experimental cams from a bygone era, that had been forsaken to forever more reside in a box under a bench with 'words do not use for the curious to muse, had escaped.............. When I rang Brook asking him what the hell they were, he only said where the hell did you find them, and that they were no good he had a much better set for the purpose.

The opening lobes are just something else. 12.5mm lift. As to when it opened and closed I haven't bothered checking, but where ever it is the power commander was set up bloody lean compared to what the ST4S cams needed. When I did the test start with a CO meter, I gave it a rev and it dropped from 5.4 to 1.5 bloody quick. The dyno guy said it was set way lean as well. Below are Brooks and 996sps

It seems our little mate from 89 had its inevitable exoticism destined from some time back thanks to Brad's Performance diaries, a tome of enlightenment. It was in for a service, tune, and a fit up of a set of ST4s headers and Termie's. It now has the added bonus of ST4S cams as well.
One of the interesting things are the before and after dyno charts. HP and Torque max figures have remained pretty much the same, 97hp and 62 ftlb. Brooks had the torque coming on pretty unevenly then a surge just before 6k to max then decomposition by 7k. Unfortunately I didn't get to ride it with them in. I have now, and it feels strong and well rounded with that raw edge. No coming on in a surprise rush at 6 ½-7 k. A definite step up from standard, which I've found to generally be a bit doey and wanting. The essence of squark power restored. I won't really know until the owner test rides it shortly and lets me know how different it feels.

Next bevel heads and high velocity porting. Chris Steadman has some interesting stuff to say, it appears he likes and uses the concept of decreasing the the choke to gain more torque. He was however along with others interrupted by what seems to be a mechanical engineer who probably just finished Uni, who basically came in touting the ridiculous nature of just quoting choke to valve ratios and stuff when there was a hell of a lot more going on. Things have come such a long way since the days of the old port and polish thats for sure.