FORMULASPEED Posted January 28, 2004 Report Share Posted January 28, 2004 Ive got a big problem. My left piston looks like silly puddy on the exhaust side of the crown. Its also missing a slight moon crest size piece where the ring sits exhaust side making the ring visible. the ring is all wavy warped. And a scuff by the left intake. My other piston looks to be ok i think. Or does it have trained eye signs of it? My crank is not welded and it backed off the pin where the lower end of the rod is butting it up to the case. On the same side as all this. Whole set up less than 1 year old I run a trinity 2-1 intake 35 pwk, 52 pilot, 225 main, needle in middle, K$N, ported, Dmc 916s, boyseen reeds, cool head 19cc domes, 110 turbo blue straight. Elevation around sea level. Oh yeah these are Namura power pistons cast and magnum crank. Today was 30 degrees and I had it jetted for 0-10 degrees. Rode it 15 minutes after a 10 minute warm up. Is this from being lean? I wasnt over heated nothing spewing out of the radiator. I realy wasnt beating on it either. So basicaly whAT IS THIS FROM. Here is the bad 1 Good piston Quote Link to comment Share on other sites More sharing options...
frocashmoney24 Posted January 28, 2004 Report Share Posted January 28, 2004 damn, how do the insides of your jugs look Quote Link to comment Share on other sites More sharing options...
FORMULASPEED Posted January 28, 2004 Author Report Share Posted January 28, 2004 They dont look to bad. There is some vertical marks by the intakes and exhaust. I can still see the cross hatchings visibly even through the marks. I hope Ill be able to get away with a hone. It was my first engine build, Thats how you learn. I posted this lookin for a direction of where I went wrong with the melted pistons. I know the crank should of been welded. I guess not many people read this section or they just ignore my posts. Quote Link to comment Share on other sites More sharing options...
. Posted January 28, 2004 Report Share Posted January 28, 2004 or we dont know what went wrong with it. It looks like it got hot. I dunno though. With the 2 into 1 setup, does it have a metal intake? With the one like that and the other one looking that much better, i'd say if it went lean it was somewhere after the intake split that it went lean, if in fact thats what happened. Quote Link to comment Share on other sites More sharing options...
PassionRE Posted January 28, 2004 Report Share Posted January 28, 2004 Which side of the motor did that piston come from?...Jim Quote Link to comment Share on other sites More sharing options...
FORMULASPEED Posted January 28, 2004 Author Report Share Posted January 28, 2004 The bad1 from the left. Quote Link to comment Share on other sites More sharing options...
PassionRE Posted January 29, 2004 Report Share Posted January 29, 2004 The reason I asked which side it was is because if your crank gets out of phase it will fire the right hand cylinder out of time and cause this. BUT since it is the left side, that rules that out. Its a little hard to tell with the pics, but it appears you have a classic case of detonation meltdown. Since your running good gas and the other side looks ok, that rules out fuel and compression ratio issues. The lack of four corner seizure, or from what I can see anyhow, rules out cooling system issues most likely. I would look closely for airleaks around the intakes, base gaskets, reed gaskets,L.H. crankseal,and also inspect the L.H. carb jets closely. Its almost a certainty that cylinder leaned out for one reason or another....Jim Quote Link to comment Share on other sites More sharing options...
FORMULASPEED Posted January 29, 2004 Author Report Share Posted January 29, 2004 I thought I was on top of the air leak. When I put all on I tightend it to specs and Tightened to specs again after a nice warm up. Using the base gaskits that came with pistons thin blue and cometic on the intakes. I even checked for an airleak 2 days befor with a colman propane torch. what would cause a crank seal to go bad? well Im going to be lookin for a new set up soon. Quote Link to comment Share on other sites More sharing options...
raggedraider Posted January 30, 2004 Report Share Posted January 30, 2004 was the gas older than a week ( wile being mixed with oil )? you loose oct rating points when you mix 2 stroke oil with gas it goes down by the day id still check for an air leak Quote Link to comment Share on other sites More sharing options...
InFlames Posted January 30, 2004 Report Share Posted January 30, 2004 only a 225 main?...hmmm Quote Link to comment Share on other sites More sharing options...
Nighty Posted January 31, 2004 Report Share Posted January 31, 2004 225 pwk rating Quote Link to comment Share on other sites More sharing options...
jbirdman Posted February 2, 2004 Report Share Posted February 2, 2004 I forgot a reed cage gasket on an engine rebuild once and the piston on that side ended up looking worse than yours. It's amazing how fast the extreme lean condition caused by an air leak can damage your top end. My coolant didn't even boil - it happened so fast that the coolant didn't have time to heat up enough. Anyway, considering that only one side was damaged, I'd say that an air leak is a very likely culprit. Quote Link to comment Share on other sites More sharing options...
boonman Posted February 2, 2004 Report Share Posted February 2, 2004 You definitely leaned out the cylinder on that side. Being that you have a 2 into 1 intake, That pretty much rules out a clogged jet. You say that the crank seperated a little. This does not mean that it went out of phase. Just as Jim (PassionRE) explained about the right side piston, I actually had this happen. I have also had the same thing you had happen to me. I have had engine failures in a few different circumstances. When you melt a piston on the exhaust side, normally it is attributed to a lean condition, making the EGT (Exhaust Gas Temperature) off the friggin charts. It gets hot enought to actually melt the piston. And it is where the exhaust exits, and wher it can be the hottest in this condition. Detonation, will usually show up as pitting on the center of the crown. And eventualy blow a hole in or near the center of the piston. This is from the detonation constantly putting undue force on the piston in this area, by virtue of the way detonation occurs. There are many other variables in it, but this is the simplest explanation. I am guessing that you have an air leak somewhere in that motor. Being that you already ripped it apart, you will never know. Now, what you do in the event of a catastrophic engine failure. LEAKDOWN test it BEFORE you even crack a bolt on that thing. THis will give you an indication of what may have happened to it. It doesn't take long to do, and can be a good indication of what you need to do to alleviate the problem.... I say take the cylinders to a shop, and see what they think. If they can be saved or not. Get a new top end kit. Have the crank checked, and welded and trued if it can be. New gaskets and seals in the lower end, and put it together. Test it for leaks, and go from there...... Quote Link to comment Share on other sites More sharing options...
FORMULASPEED Posted February 3, 2004 Author Report Share Posted February 3, 2004 For the leakdown test thats 6LBs of pressure for 6min? What do you and the rest of the big dogs recommend for gaskets? I think it was the base gasket because it was a lil gooey and tore with no force when I took it off. The other one wasnt . If my cylinder is un even at the base How can I check? what do I do Deck it? and then my port timing is lower on the top and bottom of the ports How do I correct this? On the crank seals would there be moist gritty shit around them if one was bad? Quote Link to comment Share on other sites More sharing options...
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