85 GPz550 resto [Archive] - Kawasaki Motorcycle Forums

85 GPz550 resto

12-29-2016, 05:05 AM
Hi, currently working on a resto of an 85 GPz550. Was stood outside for a gazillion years so needed more than jump leads. After a complete bike strip down and rebuild (but not the engine) all went swimmingly until getting it to run. Fired up almost instantly which was a result. However vacuum gauges showed that it had late valve timing or induction leak. After ensuring there are deffo no induction leaks I looked into why it had valve timing issues. I suspected at first the cam chain being a link out but on inspection all was ok. So after doing some research it was clear that the camshafts were 'first performance grind' so then the penny dropped. It turns out the head is off an earlier engine (H2?) while the bottom end is original A2 (engine number confirms). Pistons and barrels unsure as to if they are off the correct bike or not at this stage. Hey ho.
I have two spare engines so replaced the camshafts in the head with 'second performance grind' ones and put it all back together. Fired up straight away and ran better but still shows late valve timing. Grrrr!
It looks like I will now have to remove and replace the head shortly but am hoping that the pistons and barrels were not replaced with the earlier model ones! I know that the pistons are deffo different in the A2 to give a higher compression ratio.
Question - does anyone know if the earlier (Gpz550 H2 I am guessing c1980/82) head is identical or not to my bike which is a GPz550 A2? I have a spare head that I can swap with correct cams but don't want to replace barrels and pistons if can help it.