camatv Posted September 11, 2011 Report Share Posted September 11, 2011 ok i thought i'd throw this thread up and maybe we could have a lil discussion about detonation. its effects, its results, and what it looks like, soundls like, feels like. if you have pics of deto'd pistons and other carnage PLEASE post pictures and if the crank let go or the piston broke or any other issues you found. what the fix may have been and if possible engine set up.. i have a bunch of pics i'll get ready and throw them up.. Quote Link to comment Share on other sites More sharing options...
kodie Posted September 11, 2011 Report Share Posted September 11, 2011 (edited) The piston on the right is the right cylinder. About a week before this happened I had no idea what symptoms of detonation where. I had my right plug back out on me. Didn't really think too much about it. A week later was riding some trails and all of a sudden lost an incredible amount of power. Got it home and this is what I found. The crank didn't get effected at all just the piston and cylinder. +4 mil crank, ported by a local, +4 timing, chariot head with 22 cc stroker domes, boyesen reeds, 2 into 1 35mm pwk carb, k&n pro flow, pro circuits, lightened flywheel, We never figured out what the problem was. It happened twice, after the second time I got rid of my shee and bought my street bike. I think the local guy might have done a shitty port job. I built a very similar shee just recently and had HJR do my porting and assymbly and the motor flat out rips harder then my old motor which was virtually identical. I think he just did a shitty port on it. I don't have pics of the domes but the right dome was all pitted and chewed up just like the piston. Edited September 11, 2011 by kodie Quote Link to comment Share on other sites More sharing options...
camatv Posted September 11, 2011 Author Report Share Posted September 11, 2011 here is a nice lil write up with a lof of pics.. http://www.theultralightplace.com/pistons.htm Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted September 11, 2011 Report Share Posted September 11, 2011 To me it sounds like marbles rattling around on top of the pistons. Never herd it on my banshee. If i lug my mustang around a corner (down to or slightly below Idle speed), when I get back on the throttle it does it momentarly until the knock sensor steps in. It only does it when it is hot. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted September 11, 2011 Report Share Posted September 11, 2011 You can slightly hear it in these two videos http://www.youtube.com/watch?v=Due7mkTHMlw&feature=related Quote Link to comment Share on other sites More sharing options...
bigborebanshee Posted September 12, 2011 Report Share Posted September 12, 2011 (edited) Perfect example of detonation possibly caused by a lean condition.Look how black the crown is on the good piston.its not only black but glazed. it means it was running hot and lean before the detonation started.The piston should have some clean spots around the transfers windows and center of crown.If you are running compression that is borderline,a lean condition will accelerate the deto factor. Edited September 12, 2011 by bigborebanshee Quote Link to comment Share on other sites More sharing options...
252wheelieking Posted September 13, 2011 Report Share Posted September 13, 2011 (edited) First let me start with the set-up that I was running when this happen. Chariot coolhead, 18cc domes, BR8ES spark plugs gap (.027), wiseco pro lite 64.50 (.020), HJR dune/play port, Cometic top end gasket kit, SB IF Shearers, VF2's, Boss Racing intake w/ built in crossover tube, 34PJ's 52 pilots/CEG mid clip/160 mains, 80*+, sea level, +6 timing, 100LL av gas, stock stroke crank, new seals for complete bottomend. Below are some pics of the damage from detonation. My first sign of detonation was my right spark plug backed out on me while I was riding it. I installed a new spark plug and snugged it a little tighter than the previous spark plug. I started to notice that it was a black ring forming around the right spark plug again. I avoided it & below are the results. I didnt do a leak down test before I tore it down, but I'm leaning more to a leak from the right spark plug is what cause all this. What you are seeing below is the lower connecting rod thrust washer shattered & came threw the transfers & damaged my domes, cylinder & piston. The crank still turns smooth but has alot of play from the thrust washer being removed. Right cylinder The right dome after I wiped the oil & grit off This is the left cylinder. It would still fire on the left cylinder but run sluggish. Edited September 13, 2011 by 252wheelieking Quote Link to comment Share on other sites More sharing options...
camatv Posted September 13, 2011 Author Report Share Posted September 13, 2011 i like those pics. those are some perfect example's of deto. and also the debris wasnt so bad that it destroyed the piston, dome.. i would look at that intake. and do you rember what it sounded like when you rode it rember that sound adn try and aleviate th situation. also i know those are shelf domes but they may of had somethign to do with the deto issue,s as well as the +6 timing.. just a thought.. there is a shit ton of blow by on the pistons as well. i have noticed over the years the easier i break the motors in the more blowby i end up having .. the harder the break in the better the ring seal. rember if you cannot jet the deto away you have problems elsewere. Quote Link to comment Share on other sites More sharing options...
252wheelieking Posted September 13, 2011 Report Share Posted September 13, 2011 i like those pics. those are some perfect example's of deto. and also the debris wasnt so bad that it destroyed the piston, dome.. i would look at that intake. and do you rember what it sounded like when you rode it rember that sound adn try and aleviate th situation. also i know those are shelf domes but they may of had somethign to do with the deto issue,s as well as the +6 timing.. just a thought.. there is a shit ton of blow by on the pistons as well. i have noticed over the years the easier i break the motors in the more blowby i end up having .. the harder the break in the better the ring seal. rember if you cannot jet the deto away you have problems elsewere. Good info here. I was assuming that +6 timing was too much. Now that you put it this way, yes I do remember that pinging sound in my pipes. It sounds like a little rock or something bouncing around in the pipe. The domes could have had some part in the deto because everytime I install them my engine breaks down. Far as the blowby my compression was low as hell to be using 18cc domes. It's been time to bore & hone them, but this is what happens when your being cheap or taking the easy route. I have all new parts for the rebuild & im getting Kevin to bore & hone them this time around. I've been told the same thing as to breaking your engine in. That if you break it in hard the rings will seat better. I feel better now that I have had a 2nd opinion as to what could have been my problem with why my engine failed. Can you give me your example of a properly hard break in procedure? Thanks for the info. Quote Link to comment Share on other sites More sharing options...
252wheelieking Posted September 13, 2011 Report Share Posted September 13, 2011 (edited) here is a nice lil write up with a lof of pics.. http://www.theultralightplace.com/pistons.htm Good info here. My conditions were from the 9th pic. Edited September 13, 2011 by 252wheelieking Quote Link to comment Share on other sites More sharing options...
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