bansheerider313 Posted April 23, 2014 Report Share Posted April 23, 2014 So I have been investing in this banshee for a week or two now.I had 175psi when I originally bought it. I have done absolutely nothing to the engine yet.im about ready to order 4mm carnk and such.but I just comp checked it and its at 210psi now.wtf is going on? Brand new $150 comp guage. Even used my old one and it has same reading.what would cause this?? Quote Link to comment Share on other sites More sharing options...
blowit Posted April 23, 2014 Report Share Posted April 23, 2014 Your compression likely did not go up. Your previous reading was not accurate. When you take the head off, measure the exhaust port height and the dome size and I can tell you about where you might be. I would not be sweating 210 at all.... As long as you are on race fuel. Brandon Mull Engineering Quote Link to comment Share on other sites More sharing options...
bansheerider313 Posted April 23, 2014 Author Report Share Posted April 23, 2014 20cc domes.69.42mm pistons, ill have to check the port height. Ive been running 91.and it has hot rods ck 121 crank Quote Link to comment Share on other sites More sharing options...
bansheerider313 Posted April 23, 2014 Author Report Share Posted April 23, 2014 Yea.I gad no idea it was so high.im wanting to stroke it 4mm but idk if I can with these pistons and cylinder? . Quote Link to comment Share on other sites More sharing options...
blowit Posted April 24, 2014 Report Share Posted April 24, 2014 Yep, with about factory port height, the big bore is what is getting you. On a smaller bore, you would need about 17cc to see that. However, this is a great example of why NOT to put all your cards on pumping compression. The ratios indicate you are borderline race fuel. Quote Link to comment Share on other sites More sharing options...
n2otoofast4u Posted April 24, 2014 Report Share Posted April 24, 2014 Are these stock cylds? Sent from my SCH-I545 using Tapatalk Quote Link to comment Share on other sites More sharing options...
bansheerider313 Posted April 24, 2014 Author Report Share Posted April 24, 2014 Yes there stock. I also found that there has been milling done to the cases.for stroker crank it looks like but its a stock crank.idk whats up with that Quote Link to comment Share on other sites More sharing options...
blowit Posted April 24, 2014 Report Share Posted April 24, 2014 Obviously the cylinders have had big bore barrels put in though. Is it ported? Might be ported up for a stroker Quote Link to comment Share on other sites More sharing options...
bansheerider313 Posted April 24, 2014 Author Report Share Posted April 24, 2014 Question is can I put a 4mm crank in this with these pistons and cylinders.if so what would i need to do to lower compression and make it work. I ordered 21cc domes already to try and lower compression Quote Link to comment Share on other sites More sharing options...
bansheerider313 Posted April 24, 2014 Author Report Share Posted April 24, 2014 yes it looks like it has had a lot of porting done to it. Quote Link to comment Share on other sites More sharing options...
gonzodesign Posted April 24, 2014 Report Share Posted April 24, 2014 can I ask a question why would anyone run 210 PSI compression in a Banshee that is getting an off the shelf 4 mil crank Quote Link to comment Share on other sites More sharing options...
bansheerider313 Posted April 24, 2014 Author Report Share Posted April 24, 2014 I want to lower the compression as much as possible. Dont want this high of comp.... Quote Link to comment Share on other sites More sharing options...
LCW Posted April 24, 2014 Report Share Posted April 24, 2014 can I ask a question why would anyone run 210 PSI compression in a Banshee that is getting an off the shelf 4 mil crank Simple, torque monster dune bike with a short rpm range. I have thought about trying it, but pump gas is cheap and you can make plenty of power with it. Quote Link to comment Share on other sites More sharing options...
bansheerider313 Posted April 24, 2014 Author Report Share Posted April 24, 2014 So what do I gotta do to run a 4mm crank with this cylinder/piston combo. Quote Link to comment Share on other sites More sharing options...
gonzodesign Posted April 24, 2014 Report Share Posted April 24, 2014 I believe there is a 60% balance factor on all these Banshee cranks, when you start to get compression over 170 I think its time to change it, or do people just say screw it and run it until it blows up? Quote Link to comment Share on other sites More sharing options...
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