1015 block to 900 cases

the older cases need to be clearanced a little also.if you are going to do it you might as well split the cases and weld the crank pins and through in a new cam chain if it hasnt already been done. goodluck,happy wrenching!

Teddy, I apologize... I meant to talk about the cylinders being slight different but both the early and late cylinders will require clearancing for EITHER a Z1 case or KZ900 case MOST of the times. If you are contemplating this upgrade, it isn't difficult but the cases DO need split to clean up the mess. I would use this as an opportunitity to check bearing clearances, check the transmission and replace the cam chain. The only "tip" for splitting the cases is to chase the thread of the 8mm threads used for inserting a bolt. Once your case bolts are removed (top and bottom), the 8mm insert bolts are turned to lever the case halves apart as the case sits upsidedown. Most of the time, those threads are so grunged up, that trying to get a bolt going in them is the hardest part of the process bwhahaha If you want to do this 900 to 1015 cylinder upgrade, and don't want to split the cases unless absolutely necessary, test fit the new block on your z1 cases first. I have been told that SOME will just drop on. I am not sure why some folks have had luck. I have done this a number of times this year already and in each case, was forced to do some grinding. Since I generally split the cases, it isn't a big deal for me to just do the clean up. I can't think of a good way to do clean up with the cases not split or some method devised so that the bits removed by a die grinder don't get into the engine/transmission otherwise... but perhaps some else can.