plan to built a zrt800 stroker... anybody know what I need to do in the cylinder put 70mm stroker crank for replace the 65mm stock crank, do I need to raise the exhaust of 2.5mm and lower the port transfert of 2.5mm anybody can help me!!!

does the new crank use the same rod length? if it is, do you have enough deck height for the longer stoke, the usually don't which has you making cyl spacers to raise the jugs. Then spacers change the way you would address the port layout. If the stroke pushes the piston fps tooo high for your liking then you'll want to adjust the porting for a lower rpm. which can often be a challenge with the raised jugs. Then you start doing airflow calculations and often realize that the bigger motor spinning less rpms makes simular power as the stocker! Build it on paper first, every detail.

yes ,use the same rod, don,t want put shim on cylinder...

before i would build,i would get inportant data from stock engine. i would degree the engine out and get total exhaust port and transfer port duration. next i would check deck heighth at tdc. this is how far top of piston is in cylinder. check squish band clearance and cc combustion chamber to calculate compression ratio. after you get this data install the stroker crankshaft and check your data. if you are lucky you might have .080 deck height to play with, if not you either have to contact cometic gasket and have a base gasket made or machine the heads out so that the pistonn does not hit the head. i do not like machining heads out due to head gasket problems. next verify your port timing. you will see that stroker crankshaft will make the ports uncover more at the bottom of both the exhaust port and the transfer port. you will want to mark the piston skirt on the bottom
and see how much area is left at tdc. you do not want the exhaust port to open under the skirt of piston. you will have ventilated engine. you will have to decide on port timing and if you will want to raise ports. the stroker crank will change the duration automatically. next you will need to check and adjust your squish band leave about .040 clearance and set your compression. a good target compression ratio would be 13./1 - 14./1. thanks short block charlie