on to the Dyno

I rode Blackbob out to the Dyno centre, not running great, felt a bit strangled, so after the Dyno guy's initial shock at the bike (kinda getting used to that ) we got it up on the dyno and gave it a first run, up into 3rd gear (weird feeling doing 60 mph in a 10ft x 10ft room on a bench ) the lamda sensor was showing that at half throttle the carb was too rich and at full throttle way too lean so I pulled the carb and lifted the needle by a couple of notches. fired up again and up into 3rd again, half throttle and suddenly the engine note changed, down oin one cylinder - cut the mag and checked the pugs, lh cylinder sooted up. We checked the spark - fine on both cylinders, fired up again still only the RH cylinder, pulled off the LH rocker inspection covers inlet pushrod has snapped - BASTARD

Got the bob back to the shed with the trailer - pulled the rockerbox off and ive got one snapped and one bent inlet pushrods no stuck valves and nothing to hint at what might have caused it - so it looks lke i'll have to strip the whole motor down again

Black Bob update

Spring 2008

The story so far ........ Black Bob is a Triumph bitsa built up using a 1968 T120 front frame, a 1969 TRP Trophy motor, T140 rolling stock laced to 16" Harley rims

The motor has been tuned to give a bit more go, polished and ported head is fed by a Cobb Racing sidedraft Mikuni kit and exhaust exits through twin hi level straight through trophy pipes. Ignition is by Joe Hunt Magneto, there is no other wiring on the bikeso no need to keep the alternator. A Tony Hayward belt drive A PSP hydraulic clutch kit operates a lightweight alloy race spec clutch with an SRM pressure plate feeding the power to the 4 speed gearbox.

August 2008

The Tr6 motor had lost compression on its last run out. A top end strip down revealed badly worn bores and a broken valve spring. A Morgo 750cc big bore kit was ordered and fitted, and the valve springs replaced with some spares from the shed.