I've never really posted anything here, just added to conversations from time to time, but here it goes.
So here we are with busted pistons, but first a back story.
The past three riding seasons have been going good. The sound that I was hearing up to the point of things going kaboom I chalked it up to the floats on the carbs (36mm CRII's) jittering when the engine was under load at speed (about 60-75 mph). I would experience a rattling sound and loss of power while keeping the same throttle position. Thinking the carbs were getting starved of fuel from lack of venting, I would open the fuel filler to equalize the pressure. After a little while, the engine would pick back up and we (my '04 Speedy and I) would continue the ride. This seemed to work for quite a while.
I had the 904 big bore kit installed at my dealership when I was stationed in Florida. Six years ago, I got orders and move up to Minot, North Dakota. Which brings me to problem #1: I put in the higher compression pistons in FL (12.1:1). Instead of the stock 10.5:1. This leads to problem #2: higher octane fuel is readily available in FL...not so much in ND. The highest I have seen up here is 93, but that is only in the bigger towns. You would be hard pressed to find that in some of the tiny towns around here. 91 or even 89 would be the highest they would carry.
This all culminates to the events on 20 May. I was hosting the annual beginning of season safety ride for my squadron. I was riding tail gunner (very back) to observe and give any corrections to those that I may see having trouble riding in a group situation. We were about 20 miles from town and the engine started doing what I explained above. I took the fuel cap off and waited a bit...nothing...still losing power and speed. Downshifted to try to keep up, the rattle got real bad. As soon as I heard how loud it was, I shut the throttle and pulled over immediately. I came to a stop and the engine quit and I was greeted with the big red glow of the engine oil pressure light. I attempted once to restart the engine and when I heard the starter spinning at a much faster rate (like the engine didn't have any compression), I stopped and called for a ride (which promptly ended mine).
So below are the pictures of what I found after pulling the head. This of course is due to pinging. I have never heard an engine do this before even I know what it is. So now both myself and my wallet are getting an education.
Left piston in cylinder
Right piston in cylinder
http://s164.photobucket.com/user/joejoetoy/media/Right%20Piston%20in%20cylinder.jpgLeft piston out of cylinder
Right piston out of cylinder
Left piston measurement
Right piston inside measurement
Right piston outside measurement
Luckily I'm very certain that the pieces have exited through the exhaust. The rings were burnt, but no pieces were missing.
At least I get to address some (much) smaller issues that I've been meaning to get done on the bike as well. Change the gearing, center mount the battery, rewire a few things, repaint the header wrap and put the Scypters back on.
