Hi All - I apologise for being an infrequent contributor to the forum of late, but I am geographically "out of the loop" with Davies Motorsport since returning to the Homeland of the Isle of Man.
However.....John & the team have finally cracked the 70bhp ceiling with this year's 500/4. Now figures higher than that have been seen previously, but not at the baseline, local dyno where 99% of the runs are conducted. 70.4bhp was seen at the last dyno session, using open meggas & the most recent engine.
In less than a month, that bike will be at the Pre-TT races on the IoM, at full power, so we will see how it fairs.
Alan Oversby raced the bike this weekend at Snetterton in the CRMC meeting and won the ACU500 race, with 2bhp less (silenced) and a drum brake. Plus he put in the fastest lap.
There should be more to come too, with a new revised cylinder head going on this week, with new pistons to match.
When I first came on here asking for advice, the consensus was that the 500/4 was easy to get 65bhp out of, but a bugger to get more. You weren't wrong. It has taken 6 years of fettling, a dry clutch, a deep sump, extended engine fins, multiple exhaust systems, a cylinder head developed in Australia, all manner of crankcase breathers and a whole load more to get to this point.
In 2013 William Dunlop delivered a fantastic lap at the Classic TT in excess of 109mph. Last year, all three riders were above 106 and the two finishers both regularly delivered laps in excess of 108mph & William clocked 138.9mph through the speed trap. The target has always been 110mph average on a lap and 140mph through the speed trap. There is even a new (more classic) fairing for 2018, so here's hoping.
I will endeavour to update this after the Pre-TT.
Cheers,
Peter
