checkster Posted January 8, 2004 Report Share Posted January 8, 2004 got the head milled on my banhsee .030". figured it would give me more compression than it actually did. before was 110, now it up to 120. does this sound right? i thought it would be higher. checkster Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted January 8, 2004 Report Share Posted January 8, 2004 Don't know a whole lot about milling heads but you are right, the compression should be much higher than that...sounds like your engine isn't completely sealed tight...There are others on here that could help you to better identify the problem...something definitely doesn't sound right though Quote Link to comment Share on other sites More sharing options...
ledofthezep Posted January 8, 2004 Report Share Posted January 8, 2004 I jumped up to 150 from 120 before milling it .030 Have you ever changed out the top-end or rings? What's your mods? Quote Link to comment Share on other sites More sharing options...
checkster Posted January 8, 2004 Author Report Share Posted January 8, 2004 i have only had it about a year, its a 1997. the guy said he never rebuilt it, but when i bought it it also looked like he barely ever rode it either. dont get me wrong it ran great before the milling. maybe i should stick a set of rings in it. dont really have the funds right now for a new piston and bore. i was hoping i could bump up the compression a little and put off the top end til next winter. Quote Link to comment Share on other sites More sharing options...
cheezehead Posted January 8, 2004 Report Share Posted January 8, 2004 I jumped up to 150 from 120 before milling it .030 Have you ever changed out the top-end or rings? What's your mods? Mine was similar when I did mine as well something like 145 I think but my bike needed a rering at the time also. Quote Link to comment Share on other sites More sharing options...
mrmatt Posted January 9, 2004 Report Share Posted January 9, 2004 I went from 120 psi to 154 psi when I had 0.030" milled off. Quote Link to comment Share on other sites More sharing options...
blue95shee Posted January 9, 2004 Report Share Posted January 9, 2004 I have one for you guys. I plan on milling my head .030". I haven't checked the "before" compression yet but I am going to before I do anything so I can check the results. My question is how do I know that my head hasn't already been milled?? I have heard on here that you shouldn't remove more that .030" otherwise you will mess up the squish. So lets say that .010" has already been removed in the past. I take the head off and have .030" milled off. That is a total of .040" which is too much. Is there any way to tell if it has ever been milled or resurfaced??? I know the "before" compression check can give me an idea but how can you be sure??? Quote Link to comment Share on other sites More sharing options...
Checkmate Posted January 9, 2004 Report Share Posted January 9, 2004 I have one for you guys. I plan on milling my head .030". I haven't checked the "before" compression yet but I am going to before I do anything so I can check the results. My question is how do I know that my head hasn't already been milled?? I have heard on here that you shouldn't remove more that .030" otherwise you will mess up the squish. So lets say that .010" has already been removed in the past. I take the head off and have .030" milled off. That is a total of .040" which is too much. Is there any way to tell if it has ever been milled or resurfaced??? I know the "before" compression check can give me an idea but how can you be sure??? You should be able to look at the surface of the head and see some 'tool marks'. End mills will usually leave a directional 'patteren' in the surface that it's milling. And with the large surface area of the head, it will take a few passes (in each direction) with the end mill to skim the entire surface. So you should see the pattern that the tool followed when you look at the face of the head. Quote Link to comment Share on other sites More sharing options...
boonman Posted January 9, 2004 Report Share Posted January 9, 2004 Or, look for fly cutter marks. I myself use a surface grinder that leaves no marks. COmes out A+++++++++ And for every .010" you mill off, you should get about 10 PSI out of it. Untill you pass .030", then you are in the danger zone of squish. Your compression will raise considerably, but your squish will be fubared... Quote Link to comment Share on other sites More sharing options...
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