canyncarvr Posted May 31, 2006 Report Share Posted May 31, 2006 It's not just a matter of head volume!! Having 150psi (pick some number) doesn't tell you a whole lot! Increasing combustion pressures by 'cutting' the head is often referred to as a 'good thing' when it comes to Banshee performance. Certainly there is more to it than whacking some metal off the Banshee head. I've had port work and machine work done on heads that ended up in far less than satisfactory performance gains. Some work has even resulted in performance losses! My Banshee would not hold 6th gear WOT in the sand unless I wound it pretty tight in 5th. Certainly if there was a headwind..forget 6th altogether. Another Banshee (same mods, not as new) was the same. I bolted a modified Banshee head from RB Designs onto the second Banshee a few weeks back. 'All of a sudden', I couldn't keep up! We were riding completely different territory so I thought my machine's performance was a matter of MY sense of the different terrain. Next trip out, MY Banshee had an RB head on it, too. Well well.... The two machines ran fairly equally...'all of a sudden'. I had far better throttle response and pull in lower throttle ranges..AND 6th gear pulled great not only with a short shift from 5th but from about 25mph! Headwind? No matter. Combustion pressure (kick speed) only changed about 12psi. Obviously the changes made in squish angle and piston clearance mattered a whole lot, too. What a treat to ride!! Beautiful work...done quickly, too!! Real quick. Impressive stuff. Quote Link to comment Share on other sites More sharing options...
Screamin_Banshee Posted June 1, 2006 Report Share Posted June 1, 2006 Share with us who did the head work, professor. Could help some of the guys out who are still running a stock and looking for a bump in power. Quote Link to comment Share on other sites More sharing options...
canyncarvr Posted June 1, 2006 Author Report Share Posted June 1, 2006 Share with us...professor... No 'professing' intended..and I don't play one on TV, neither! RB Designs (the one I referred to..Google comes up with numerous others of the same name) is in Portland, OR. He can be reached through RB-Designs.com. Disclaimer: I am not affiliated with RB-Designs in any way. I have used his services to improve the performance of my dirtbike, friends dirtbikes and the two banshees currently in the garage. I have his modified carbs on both Banshees too..that's another work of art that works! Saying I've had machine work (port jobs, head modification) done that was far less than acceptable, let alone 'good' is NOT any reference to any other's work I've seen referenced on this site, BTW. Not at all..in no way. Mr. Black (the 'B' in 'RB') is a super nice guy for starters..and his work is excellent because it works..and it's pretty, to boot!! This likely fits better in the product reviews forum.... Quote Link to comment Share on other sites More sharing options...
csrmel Posted June 2, 2006 Report Share Posted June 2, 2006 this is true. you can think of a banshee, or any 2stroke for that matter, as literally a supercharged engine. the exhaust pipes literally act as a supercharger to force more air into the engine than it could normally get on its own. why would anyone want to run high compression heads on a supercharged engine? doesnt make much sence to me. (unless you run alchy) thats counterproductive to gaining power. its the reason why the stock banshee has only a 6.5:1 compression ratio. if you go to some aftermarket websites who make banshee heads, none of them talk about proper squish design, theory and practice. i havent found one yet that says anything about their squish. just more billet bling to slow ya down and burn a hole in ur wallet. but this is sadly, the normal thing to do because more people dont even know what squish is. they just think (higher compression-more power) when it simply isnt true. Quote Link to comment Share on other sites More sharing options...
canyncarvr Posted June 3, 2006 Author Report Share Posted June 3, 2006 (edited) I'll take it in little steps for you. Peddle fast, now!! this is true. you can think of a banshee, or any 2stroke for that matter, as literally a supercharged engine. the exhaust pipes literally act as a supercharger to force more air into the engine than it could normally get on its own. Pretty much. That's the point of having diverging/converging bells on a 2-stroke pipe (expansion chamber). There is a return pressure wave that results from those bells that, depending on size, shape, and length pushes air/fuel mixture back into the chamber...that mixture that is 'new' and IN the pipe due to the scavenging effect of that same pressure wave moving in the opposite direction a bit earlier in time. That's where the wet-line jetting method comes from. But, you have probably read all about that in some aftermarket websites who make banshee heads. why would anyone want to run high compression heads on a supercharged engine? Pretty much. 'High compression' on a supercharged engine is not a good thing. Which, of course, is why SC engines rarely run over 3:1 static compression. Now...that would be 'low compression'! Maybe there's a place somewhere inbetween that works better? Is such a possibility even remotely possible? doesnt make much sence to me. (unless you run alchy) thats counterproductive to gaining power. its the reason why the stock banshee has only a 6.5:1 compression ratio. Hhhmmm....so an alcohol fueled engine does run 'hi compression'? Whether injected, carbureted or stuffed (roots, centrifigal or turbo'd) probably doesn't matter? if you go to some aftermarket websites who make banshee heads, none of them talk about proper squish design, theory and practice. i havent found one yet that says anything about their squish. If they bothered to explain it to..well, some (if the shoe fits and all that...) those 'some' probably wouldn't understand it. Besides that, why would any 'aftermarket website who makes banshee heads' even consider explaining what they do to make their 'stuff' work? just more billet bling to slow ya down and burn a hole in ur wallet. but this is sadly, the normal thing to do because more people dont even know what squish is. Billet bling? I'm sorry...you are of the understanding a squish is something shiny you bolt onto your muffler for jazz effect? ...summore. I would be interested in a lesson on squish from you if you have the time: What it doesn't do, why it's not important, and why everyone shouldn't care about it. they just think (higher compression-more power) when it simply isnt true. As a blanket statement, that is true. Higher compression is not always a good thing. OK...enough fun with all that....... The math (I won't bother you with the details) tells me the banshees with a RB Designs modified head change to approximately 6.9:1 over the 6.5:1 advertised in a stock banshee engine. I wouldn't call that 'high compression'. You would be hard-pressed to find anyone that would call that minimal change much if any significance, let alone 'high compression'. A basic understanding of internal combustion engines (2 or 4-stroke), the actual 'combusting' part of them, will include if not an understanding of all the whys and wherefores of the importance of squish (angles, depth, shape etc) at least the glimmer of a thought that it means something. A lot, actually. The magic is in the squish!' Wow! Now wouldn't that be an ignorant thing to say!! I've never heard that myself..I would certainly benefit from perusing more 'aftermarket websites'. Hey!! I found one!!! There are many reasons why a particular head design works for certain types of racing. For example; a head with a wide squish band and a high compression ratio will generate high turbulence in the combustion chamber. This turbulence is termed Maximum Squish Velocity, MSV is rated in meters per second (m/s). A cylinder head designed for supercross should have an MSV rating of 28m/s. Computer design software is used to calculate the MSV for head designs. In the model tuning tips chapters of this book, all the head specs quoted have MSV ratings designed for the intended power band changes. That, btw from: HERE! Imagine that! Doesn't everyone know what their meter-per-second squish velocity is? Of course they do!! That's why you don't read much about it on all the aftermarket websites! Why belabor the obvious!!?? ..for the very last time..honest! Well, of course there is always the possibility that Eric Gorr is a baboon and a maroon, too!! Obviously he's the master of billet bling AND the King of Slowdown! OK. Enough fun...really! I do NOT know all about squish, MSV and how to change the former to increase OR decrease the latter. I know what works, though. But, heck....I've only ridden, rebuilt and modified 2-strokes for hundreds of thousands of miles and for over 35 years. Please do note the signature? 'Consider the source!' Well..and that latin stuff the meaning of which likely escaped...some. Cheers! Edited June 3, 2006 by canyncarvr Quote Link to comment Share on other sites More sharing options...
ironhead Posted June 4, 2006 Report Share Posted June 4, 2006 wow! im lost now! maybe its from the keystone ice ! Quote Link to comment Share on other sites More sharing options...
csrmel Posted June 5, 2006 Report Share Posted June 5, 2006 canyncarvr, read this. http://www.nizkor.org/features/fallacies/straw-man.html thats all i have to say on this discussion. Quote Link to comment Share on other sites More sharing options...
canyncarvr Posted June 5, 2006 Author Report Share Posted June 5, 2006 canyncarvr, read this. http://www.nizkor.org/features/fallacies/straw-man.html thats all i have to say on this discussion. OK. I did. The funny part of that is I understand: 1. The meaning of the phrase, AND 2. How it does not apply in this case. You presented an argument (more complaint, really) that was wrong, unfounded, incorrect, in error, and misguided. I corrected the error with fact. That you do not understand is a perfect example of something not understood to be therefore considered by the one lacking understanding to be bogus. You are welcome to take issue with the facts of the matter. ....makes your point of view no less wrong. You're welcome to it, though! Quote Link to comment Share on other sites More sharing options...
brodysblanshee Posted June 7, 2006 Report Share Posted June 7, 2006 The funny part of that is I understand: 1. The meaning of the phrase, AND 2. How it does not apply in this case. Um, I believe he was AGREEING with you man... Quote Link to comment Share on other sites More sharing options...
RILS Posted June 7, 2006 Report Share Posted June 7, 2006 this is true. you can think of a banshee, or any 2stroke for that matter, as literally a supercharged engine. the exhaust pipes literally act as a supercharger to force more air into the engine than it could normally get on its own. why would anyone want to run high compression heads on a supercharged engine? doesnt make much sence to me. (unless you run alchy) thats counterproductive to gaining power. its the reason why the stock banshee has only a 6.5:1 compression ratio. if you go to some aftermarket websites who make banshee heads, none of them talk about proper squish design, theory and practice. i havent found one yet that says anything about their squish. just more billet bling to slow ya down and burn a hole in ur wallet. but this is sadly, the normal thing to do because more people dont even know what squish is. they just think (higher compression-more power) when it simply isnt true. Ok smply said go get you a noss head throw on some 18 or 19cc domes and some race gas,come back and say you lost power.If you do this I doubt we will here you arguing that low compression is better.There is a middle factor but its not at 125psi.If you go real high say 185psi you will see some good gains low but it will not rev on top like it will with say 160psi but either of these will perform better than stock compression. Quote Link to comment Share on other sites More sharing options...
Shee-Male Posted June 7, 2006 Report Share Posted June 7, 2006 This whole ting sounds lika a late night infomertial. Quote Link to comment Share on other sites More sharing options...
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