The bike is a MC28 with a recent TYGA 300 top end kit plus TYGA expansion pipes, jetted to TYGA's base line spec. Starts and runs immediately, fresh premium fuel at 30:1. Has some issues with a dead tacho that now is alive so I can track the revs where the power comes on / off.

A test ride round the block with the dead tacho felt good, but I'm not the owner and my seat of the pants feel may well be different to his (and its been a few years since I flogged RDs and LCs for fun).

I may have a potential problem with the exhaust power valves - I see no movement at all when revving on the stand (and of course not visible running down the road). The motor gets very sluggish at 5000RPM revving in neutral. I would have expected a characteristic boost at the point. The wiring is ex OE, assuming it has the PGM4 unit signalling the RC servo motor to wind in the cables.

Does anyone have info on what to check in terms of wiring inputs and when on the stand how the RC valves should respond and at what RPM should they activate?

Next - with the carbs running open, (no OE airbox) I'm wary of track dust and debris getting in, so I was thinking of a K&N filter. Billions of types on their website, what looks practical is the oval unit with 2 flanges. Anyone got a recommendation for the make / model of what they know works.