Hi. There are plenty of spares for that engine at JP, but also you can use the group (piston-sleeve and underhead) of R01 or R03 (7 or 8 ports version). The conrod is the same also, newer versions but same size.

If you use a r01 group you can save your underhead (although the piston-sleeve from jp here come also with conecting rod and underhead). In fact 2003 WC has the same internals as FX21R01, is almost the same engine with JPFX logo instead of NOVAJP logo.


If you use R03 internals (7 or 8 ports) YOU CANNOT USE your WC underhead, R03 under head enter deeper in the crank case and the piston is shorter. Also when you buy a R03 rebulding kit comes with piston-sleeve,conecting rod and underhead, so no problema at all.


Using the R03 kit in your 2003WC will increase performance close to a total R03 engine, the mileage will be reduced a bit , so think in using 8.5mm air reducer instead of the 9mm that came with old WC engines.

I've been using several R03 ceramic bearing engines (4 engines) these season and also i rebuild an old WC as 5h engine to use as training engine, and I ended using that rebuilt engine in one national A-Main, I ensure the JP WC rebuilt with R03 internals performs really nice. Of course before check the geometry of the crack shaft pin and bearings, i also changed both bearings in the rebuild but it was worthy.


PD: This kind of rebuild is not an experiment , JP itself says it fits perfectly.

PD2: JP RX21 WC's were probably one the best engines ever made, in fact japaneese top drivers still were using them not long ago (2005). I race JP engines since 2003, used a lot of R03 in 2005-2006 and WC is not much slower than actual R03 or jpnova plus35.

Best Regards