jasonsb Posted January 27, 2005 Report Share Posted January 27, 2005 I was doing some drag racing this past weekend in the sand when my bike suddenly took a shit. It was hard to start, mis firing, and sounded strange. I stopped riding it right away and loaded it up. Got home and found that one of my plugs has silver flakes on it. What do you think I'm looking at? Top end, boring, honing, rods, crank, etc... I know I won't be able to tell without taking it apart, but has anyone had any experience with this. I plan on doing the work myself. Quote Link to comment Share on other sites More sharing options...
ledofthezep Posted January 27, 2005 Report Share Posted January 27, 2005 Couldn't tell ya for sure...could be a ring that snapped, could be junks of grunt off your piston, no telling from here. Check your compression 1st & see what numbers you come up with, then post. If you're compression is shit, pull off the head off & see what's up. let us know what ya find. Quote Link to comment Share on other sites More sharing options...
jasonsb Posted January 28, 2005 Author Report Share Posted January 28, 2005 I will borrow a friends compression tester and go from there. I just remembered something else...while trying to start it, a rattling noise could be heard. The first thing I thought was "piston rings". Quote Link to comment Share on other sites More sharing options...
RNBRAD Posted January 28, 2005 Report Share Posted January 28, 2005 I will borrow a friends compression tester and go from there. I just remembered something else...while trying to start it, a rattling noise could be heard. The first thing I thought was "piston rings". 313404[/snapback] No question about it, take that head off and see what's up. Don't crank on it anymore or you may ruin your head/domes. Quote Link to comment Share on other sites More sharing options...
joshv5.0 Posted January 28, 2005 Report Share Posted January 28, 2005 No question about it, take that head off and see what's up. Don't crank on it anymore or you may ruin your head/domes. 313434[/snapback] don't do like i did and keep riding it to get it back to the truck. that decisoin cost me about a grand Quote Link to comment Share on other sites More sharing options...
banshee tuner Posted January 28, 2005 Report Share Posted January 28, 2005 Does not sound good, probably going to need a top end rebuild kit. Quote Link to comment Share on other sites More sharing options...
Fireman-hott Posted January 28, 2005 Report Share Posted January 28, 2005 This piston crown has an ash colour, which shows that the engine has run hot. The ash colour is actually piston material that has started to flash (melt) and turned to tiny flakes. If this engine was run any longer, it probably would've developed a hot spot and hole near the exhaust side and failed. The main causes of this problem are too lean carb jetting, too hot spark plug range, too far advanced ignition timing, too much compression for the fuel's octane, or a general overheating problem. Probably what your looking at on the piston so expect a minimum new pistons and hone/bore job depending on how the wall looks. Change out the oil in your crankcase too in case any of the flakes got down in there. http://www.mztech.fsnet.co.uk/workshop/wrk_piston.html Good site to look at when you get the top end off, you can match the damage to the pictures and get an idea of what went wrong. Quote Link to comment Share on other sites More sharing options...
dlnoss Posted January 28, 2005 Report Share Posted January 28, 2005 You were running race gas weren't you? 19cc domes, advanced timing, sea level..... Quote Link to comment Share on other sites More sharing options...
jasonsb Posted January 29, 2005 Author Report Share Posted January 29, 2005 You were running race gas weren't you? 19cc domes, advanced timing, sea level..... 313810[/snapback] Yeah I was running race gas...3 gallons of 110 and 2 gallons of 91. The bike was running perfect. The only thing I changed were the plugs. I put br8es plugs in. I used to run br9es. I thought I try the standard plugs and see if my plugs would stop fouling. I am running advaced timing +5 with mild porting, 350 jetting. I know it's going to need new pistons...Has anyone tried the pistons that have boost ports in them. I think vito's has them. Quote Link to comment Share on other sites More sharing options...
jasonsb Posted January 31, 2005 Author Report Share Posted January 31, 2005 ITS NOT GOOD! I pulled the coolhead off, pipes, and intakes off. I pile of shaved metal was in the pipes. A piece of a copper washer was inside the cylinders. That was what was eating up the rightside piston. This is exactly what happened to my dirtbike last year. I think I'm looking at damage to a crank/rod thrust washer. I'm going to have to split the case. Can the cranks be rebuilt? By the way, what causes this to go bad? I bought the bike used 3 years ago. I replaced the top end but never messed with the bottom. Quote Link to comment Share on other sites More sharing options...
ssanddemon Posted January 31, 2005 Report Share Posted January 31, 2005 You need to retard your timing (to standard). Running the tight compression domes and advanced timing makes me think you are most likely the victim of detonation. If you want to make big power, now is the time to look at a stroker crank, clearance the case to fit, and to bore out those cylinders. You are gonna be spending some money just to bring it back to where it is, and to run safe, you wiil be down on power unless you upsize your beast. Quote Link to comment Share on other sites More sharing options...
jasonsb Posted January 31, 2005 Author Report Share Posted January 31, 2005 Just thought I'd share a few pics from the pistons and the domes. One piston is chewed to hell. Both domes look like they were being worked for a while. Quote Link to comment Share on other sites More sharing options...
jasonsb Posted January 31, 2005 Author Report Share Posted January 31, 2005 Look in the picture above...you can see the small thrust washer sitting under the domes. Quote Link to comment Share on other sites More sharing options...
jasonsb Posted January 31, 2005 Author Report Share Posted January 31, 2005 This piston is not too bad but it has a few dings in it. Quote Link to comment Share on other sites More sharing options...
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