question on rz port timing for those who know....

[sumoshee]

im converting my shee into a reverse cyl rz ypvs,ive bought some ported rz cylinders off ebay,i took the time to measure the port heights just to compare against the standard rz,i dont know who has ported them. now i want to run a 4mm stroker/longrod crank with these cylinders,there only on the second rebore so i dont want to resleave them if poss,my concern is with the port timings that have been changed somewhat,can i expect these cylinders to kick ass or run like a bag of poo? port heights are as follows,all measurements from cyl deck,

exhaust port top=26.35mm
bottom= 54.85mm

front transfer ports top=43.00mm
bottom=54.4mm

rear transfer ports top=43.46mm
bottom=54.10mm

boost port top =42.06mm
bottom=59.20mm

intake ports top=72.42mm
bottom=104.96mm


i hope somebody can make some sense of this,i know i will need to play with the port timing for the 4mm crank,im just not sure these are useable? any advice will be greatly appreciated,happy easter guys..........

[flotek]

exhaust is 197 degrees
front transfers are 120 degrees
rear transfers at 118 degrees

these^ are the main numbers ot be concerned with

whoever ported these was a shade tree engine builder they hardly did anything to the transfers (which is very common cause its the hardest part to cut without the right tooling and knowhow)as they sit you have around 39 blowdown (relationship to the exhaust and transfers opening ) this is way off and will make a narrowpeaky powerband with low torque especially with the exhaust being at 197 degrees ,now with that being said its very possible to use a 4mill crank on these but you wont be able to use a spacer instead recess the domes in the stock RZ head 2mm or less for more compressionand proper squish and ru na thin cometic steel base gasket around .015 thick . now for the porting the ports will all need dropped 2mm.. the transfers need raised and now were shooting ofr a 34 blowdown for maximum potential on gas this will put yo uaround a 128-129 transfer duration , dro pthe opening of the upper boost port and intake windows as well to start the charge earlier /sooner and help scavenging ,of coarse this is approximate of what needs done but itll give yo uan idea ,really your better off sendin it out to someone who is a profesional builder that can map it out can calculate al lthis stuff ,search around the net and your area and ask other rz owners who they liked or disliked ,an rz is similar to a banshee so a good banshee guru could really help and happy Easter to you and your family

[sumoshee]

hey flotec your a diamond,i realy appreciate your input,thanks for takin time out to help,

[flotek]

no problem bro ,and maybe someone down the road can benefit for mthis thread during a search