yamaha man Posted July 9, 2008 Report Share Posted July 9, 2008 Ok so my stock crank recently went bad. I was going to upgrade to a 4mill but I was wondering do u have to do any case work or cylinder work??? Oh and Im running stock cylinders. Quote Link to comment Share on other sites More sharing options...
Washburn Posted July 9, 2008 Report Share Posted July 9, 2008 se work but if your running a 4mil with longrods which is a good idea you should atleast have it ported to match the longer stroke get new weisco 795 series pistons and get your domes cut for a stroker engine. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 9, 2008 Report Share Posted July 9, 2008 Yep. Long Rod Crank 795 Pistons Cut Cool Head Stroker Domes Port work is preferd but not required to make it run. Quote Link to comment Share on other sites More sharing options...
yamaha man Posted July 9, 2008 Author Report Share Posted July 9, 2008 I forgot to mention my stock crank has a long rod in it.... Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 9, 2008 Report Share Posted July 9, 2008 I forgot to mention my stock crank has a long rod in it.... If you have the stock stroke long rod crank then you just run the same pistons you ran with it. You ethire need to run Cut Stroker domes or the Cylinder Spacer Plate. Cut domes is the way to go. There is no other work that is nessessary for the crank. Port work would be a great bonus but not requrired. josh Quote Link to comment Share on other sites More sharing options...
yamaha man Posted July 9, 2008 Author Report Share Posted July 9, 2008 will i loose alot of hp if I dont port it? Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 9, 2008 Report Share Posted July 9, 2008 will i loose alot of hp if I dont port it? You wont loose a lot you just wont gain near as much. When you port a 2 stroke it is like putting in an aftermarket cam shaft in a 4 stroke. The porting controls when air and fuel go in and when exhaust goes out. Quote Link to comment Share on other sites More sharing options...
Washburn Posted July 9, 2008 Report Share Posted July 9, 2008 You wont loose a lot you just wont gain near as much. When you port a 2 stroke it is like putting in an aftermarket cam shaft in a 4 stroke. The porting controls when air and fuel go in and when exhaust goes out. Yep, more flow more go, The bigger your ports are the more gas and air goes through them and boom you just got all of that power from simply expanding your ports. Is it so easy you can do it yourself yes and no. I wouldent recomend it without a port map and a steady hand. The guys that port all of the time are used to it and they can grind them rite out. I do however recomend the rite port job from the rite guy. A builder who does drag ports all day wont give you as good of an engine as a guy who does woods ports all day if thats what you want. Quote Link to comment Share on other sites More sharing options...
yamaha man Posted July 9, 2008 Author Report Share Posted July 9, 2008 I dont know how im gonna report it.. it already has a huge drag port done to it... btw do they sell cut domes?? Quote Link to comment Share on other sites More sharing options...
Washburn Posted July 9, 2008 Report Share Posted July 9, 2008 I dont know how im gonna report it.. it already has a huge drag port done to it... btw do they sell cut domes?? Well if it already has a drag port then it probably doesnt need touched. Only thing I can think of is having your intake raised a little but you probably dont need it. Nossmachine.com has domes cut for any aplication you need just state what your looking for and David Noss will get them rite out to you. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 9, 2008 Report Share Posted July 9, 2008 I dont know how im gonna report it.. it already has a huge drag port done to it... btw do they sell cut domes?? You cant report them for the 4 mill. 4 mill crank allows the piston to fall 2mm farther down in to the cylinder, it also pops up 2mm out of the cylinder. First thing a 4 mill port job does is lower the intake and transer ports down 2mm. So when the piston is at bdc the ports are even with the top of the piston head. Your stock stroke cylinders have alreay huge ports. You cannot take 2mm of the bottom of the ports because it will make it run like crap. they will be to big. just call up www.nossmachine.com they will have the domes you need for your cool head. BHQ members get 10% off too. josh Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted July 10, 2008 Report Share Posted July 10, 2008 You're outa luck trying to run the drag ported cylinders you have now with a 4mil. You will end up with way too much transfer duration. If your cylinders were cut by a big name builder or have some impressive time slips to go with them you may get some good $$ out of them, then start with some virgin cylinders for the 4mil. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.