b-nasty Posted January 16, 2009 Report Posted January 16, 2009 Im building a 4 mill cub motor. Using a 4mill hotrods crank and cub cylinder with coolhead. With this setup do i need to run a spacer plate under the cubs or just have my domes cut for the 4mill. What works best. thanks Quote
lowbuckracing Posted January 16, 2009 Report Posted January 16, 2009 Im building a 4 mill cub motor. Using a 4mill hotrods crank and cub cylinder with coolhead. With this setup do i need to run a spacer plate under the cubs or just have my domes cut for the 4mill. What works best. thanks Did you buy a cub built for stock crank or for 4 mill crank?If its a 4 mill cub cylinder you wont need a spacer...If you find out that you do need a spacer just hit up HJR herrjugsracing,he has a guy that does a special cut for domes... Quote
b-nasty Posted January 16, 2009 Author Report Posted January 16, 2009 Its a 4mill big bore cylinder. Quote
sheefreak Posted January 16, 2009 Report Posted January 16, 2009 It is casted as a 4 mill so there is no need for cut domes or spacer plate. Just have to have big bore domes for the 68 bore. Quote
BellicoseBanshee Posted January 16, 2009 Report Posted January 16, 2009 Do not forget to check the squish clearance when you install the top-end. :thumbsup: Quote
kawiking Posted January 16, 2009 Report Posted January 16, 2009 squish = IMPORTANT should just need 4 mil cut domes. are u running alky or gas ? Quote
b-nasty Posted January 16, 2009 Author Report Posted January 16, 2009 I think im going to start off with gas then move to alky later on when i get the bugs worked out. Quote
sheefreak Posted January 16, 2009 Report Posted January 16, 2009 squish = IMPORTANT should just need 4 mil cut domes. are u running alky or gas ? Am I missing something? Why would he need 4 mill cut domes? Quote
rubberneck Posted January 16, 2009 Report Posted January 16, 2009 Yup, no 4 mil domes needed, they just need to be for the 68 mm bore. The 68 mm pistons are blaster pistons and have a different dome shape than the banshee pistons. Just order a set of domes for a 68 mm cub from one of the sponsored vendors on here and you will be fine. Because you have the 58x68 cylinder, you will not need a spacer and the pistons will not protrude from the top of the cylinder either. Check you squish clearance, and you want a MINIMUM of .040" My bike has .053 right now and seems to be fine although some have told me thats on the loose side of things. Quote
kawiking Posted January 17, 2009 Report Posted January 17, 2009 Am I missing something? Why would he need 4 mill cut domes? lol.. i was thinking stock cyl.. Quote
shanYE west Posted January 17, 2009 Report Posted January 17, 2009 lol.. i was thinking stock cyl.. Way to be ontop of things Rico!! lol Quote
dajogejr Posted January 18, 2009 Report Posted January 18, 2009 My advice is get a set of domes for gas, and get a different set for alky once you switch over. They are two different fuels with different explosion characteristics. Nothing wrong with .053 squish. Mine was at .055. I could tighten mine up...but then I couldn't run as much timing as I want, and I can't hot lap it. I will take the 5% performance decrease (if that) in order to be able to ride my bike...ALOT. Quote
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