Titan up Posted March 16, 2009 Report Share Posted March 16, 2009 I want to know why there is missing material in the ring area on the both pistons. Just on the sides though. Could be excessive rod end play. What kind of condition is your crank in? could of twisted out of phase and that would cause detonation and cast pistons don't hold up very long to deto, if they are cast, which they look to be. Also might have a little air leak, because there's some erosion on the exhaust side of your "good" piston. Quote Link to comment Share on other sites More sharing options...
kodie Posted March 16, 2009 Author Report Share Posted March 16, 2009 i have no idea why shit is missing around the ring area thats what i was hoping to find out. as for the crank it was brand new when we dropped it in i didn't stay around long after we got the juggs off had to get home so i don't know what it is like now. Quote Link to comment Share on other sites More sharing options...
rubberneck Posted March 16, 2009 Report Share Posted March 16, 2009 I want to know why there is missing material in the ring area on the both pistons. Just on the sides though. Could be excessive rod end play. What kind of condition is your crank in? could of twisted out of phase and that would cause detonation and cast pistons don't hold up very long to deto, if they are cast, which they look to be. Also might have a little air leak, because there's some erosion on the exhaust side of your "good" piston. Broken ring lands = detonation. My guess is that its too much compression for 93 octane. You are running a 4mil, so a 22 cc head is probably pushing the envelope for pump. Did you do a leak down when built to rule out an air leak? Did you do a compression test? Cant help you on jetting, never ran a single carb. Quote Link to comment Share on other sites More sharing options...
dco3100 Posted March 16, 2009 Report Share Posted March 16, 2009 Broken ring lands = detonation. My guess is that its too much compression for 93 octane. You are running a 4mil, so a 22 cc head is probably pushing the envelope for pump. Did you do a leak down when built to rule out an air leak? Did you do a compression test? Cant help you on jetting, never ran a single carb. how would u go about doing a leak down? Quote Link to comment Share on other sites More sharing options...
shanYE west Posted March 16, 2009 Report Share Posted March 16, 2009 I was jus gonna say it look like deto. Probably caused from lean condition (air leak). If something is wrong with a motor and I'm about to tear it down.. I always do a leak down test to rule that out first. You gotta make or buy a leak down tester. Quote Link to comment Share on other sites More sharing options...
kodie Posted March 16, 2009 Author Report Share Posted March 16, 2009 so what should i be running in her? 100 or 110? and does anything else cause deto? Quote Link to comment Share on other sites More sharing options...
shanYE west Posted March 16, 2009 Report Share Posted March 16, 2009 detonation is caused by alot of things. usually jetting. Not saying that your jetting was off.. but a airleak changes your jetting wich makes the motor run lean.. Lean conditons run hot, and that inturn brings on detonation. Incorrect dome designs can be more prone to detonation then others also. as stated before.. A crank being out of phase can cause detonation also as it could increase your timing to some ungodly amount. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted March 16, 2009 Report Share Posted March 16, 2009 I'd try better fuel, check all your clearances...but seeing the burn marks on the bottom side of the piston means it got REAL hot at the crown then grenaded on you. You need to check compression ratio, not just cranking compression to figure out what fuel you need. As said, lack of octane, air leak, lack of fuel (I think you're jetting sounds about right...or close enough) all can cause this. Quote Link to comment Share on other sites More sharing options...
T_Shee Posted March 16, 2009 Report Share Posted March 16, 2009 (edited) how was the bike running before it did this?. oops just re read your first post. so nothing was outta the ordinary when your were riding? Edited March 16, 2009 by T_Shee Quote Link to comment Share on other sites More sharing options...
kodie Posted March 16, 2009 Author Report Share Posted March 16, 2009 (edited) no bike was running fine how do i check to see if the crank is out of phase? Edited March 16, 2009 by kodie Quote Link to comment Share on other sites More sharing options...
deckheight Posted March 16, 2009 Report Share Posted March 16, 2009 With pistons and cylinders installed. Mount a degree wheel on the crank nose, bring one piston to TDC with a dial indicator and index the degree wheel w/a pointer. Bring the other piston to TDC with the dial indicator, degree wheel should read 180 deg. at the pointer. Like has already been said... Classic detonation. Deto finally ate off the piston crown on the exhaust side, ring poked into the exhaust port and got chewed up. Increase your fuel octane or increase your trapped volume with larger domes. Your right cylinder is running hotter than the left (as usual on a Banshee). Left slug doesn't look too far behind the right on the deto meter either Stagger your main jets two numbers and/or stagger your trapped volume .3 to.5cc to compensate. Just from the pics and description... Probably needing 100 octane or so on the fuel??? Hard to tell for sure without an accurate CR. no bike was running fine how do i check to see if the crank is out of phase? Quote Link to comment Share on other sites More sharing options...
03bansheeLE Posted March 16, 2009 Report Share Posted March 16, 2009 I have a very similar experience and have no idea yet what is going on. I bought my banshee last summer and it was all stock except for sniper pipes. The jetting was spot on when I got it and I rode it all summer. In september my buddy took it for a ride and brought it back 10 mins later running on just the left cylinder. I took it home and there was no compression on the right side so I tore it apart and the rings were melted into the piston and the cylinder was grooved, left side was still clean. I figured he just heated it up too much and bought some Vito's Super Stock pistons .060 over with the jet kit and got a local machine shop to bore and hone the cylinders. I broke the bike in and constantly checked the jetting with new sets of plugs, dark brown colour. I did a compression check on it a week ago and left was 120 and right was 90. Baffled, I figured ill do I full rebuild on it this time so I went out for one last ride yesterday and when I was just coasting down a hill, it locked up and died instantly. Tore it apart at home and the right piston rings were melted again and got stuck in one of the ports and the cylinder is grooved again, this time the left side piston skirt had started to wear in one spot against the cylinder wall. Rod and crank bearings are fine, carbs are in sync and jetted properly. Im thinking maybe a crank seal but I don't have any experience with banshees. I noticed the lower reeds on both cages arent quite closing all the way aswell, Im pretty sure this isn't normal. Don't mean to hijack your thread, just didnt want to start another one thats exactly the same. Quote Link to comment Share on other sites More sharing options...
kodie Posted March 16, 2009 Author Report Share Posted March 16, 2009 thanks guys ya the left one just started to fuck when the right one was totaly gone. when do you guys stop boring a jugg? 80 over to be safe? i know they go to 100 but i thought i saw where alota people stoped at 80 Quote Link to comment Share on other sites More sharing options...
03bansheeLE Posted March 16, 2009 Report Share Posted March 16, 2009 Im pretty sure .080 is the most for reliability and longevity. Quote Link to comment Share on other sites More sharing options...
deckheight Posted March 17, 2009 Report Share Posted March 17, 2009 Start a new thread w/pics... Your minus .030" OEM head is the first red flag! Somebody here will figure it out, just need more info and pics if possible... I have a very similar experience and have no idea yet what is going on. I bought my banshee last summer and it was all stock except for sniper pipes. The jetting was spot on when I got it and I rode it all summer. In september my buddy took it for a ride and brought it back 10 mins later running on just the left cylinder. I took it home and there was no compression on the right side so I tore it apart and the rings were melted into the piston and the cylinder was grooved, left side was still clean. I figured he just heated it up too much and bought some Vito's Super Stock pistons .060 over with the jet kit and got a local machine shop to bore and hone the cylinders. I broke the bike in and constantly checked the jetting with new sets of plugs, dark brown colour. I did a compression check on it a week ago and left was 120 and right was 90. Baffled, I figured ill do I full rebuild on it this time so I went out for one last ride yesterday and when I was just coasting down a hill, it locked up and died instantly. Tore it apart at home and the right piston rings were melted again and got stuck in one of the ports and the cylinder is grooved again, this time the left side piston skirt had started to wear in one spot against the cylinder wall. Rod and crank bearings are fine, carbs are in sync and jetted properly. Im thinking maybe a crank seal but I don't have any experience with banshees. I noticed the lower reeds on both cages arent quite closing all the way aswell, Im pretty sure this isn't normal. Don't mean to hijack your thread, just didnt want to start another one thats exactly the same. Quote Link to comment Share on other sites More sharing options...
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