Project Yamaha YZF-R1 5VY part 5: Where fuels rush in…

Final preparations for PB’s Spanish track test go awry with a mystery rich-running problem…

- PAUL BERRYMAN

Last time out you’ll have seen me buy the engine from a fairly humdrum middleweight bike (FZ8) to repair my stricken 5VY R1.

This was only after ascertaining that inside it were all the R1-based goodies I needed to rebuild mine – namely crankshaft and rods, plus also some other ‘nice-to-have’ parts like a clutch basket that didn’t rattle and crankcases that didn’t have oil ways filled with clutch plate and flywheel magnet grinding paste…

Engaging the significant help of R1 guru Pete Beale, the largely scrap 5VY motor and low-mileage breakers yard FZ8 motor were fused together to create a totally refreshed engine. When complete it had the later model R1 crank and rods found in the parts bin FZ8, as well as all-new crank shells and main bearings. A light head skim and blueprinted cam-timing completed the rejuvenation and offered the prospect of a few more bhp too – lovely!