Antifreeze in the oil, and combustion chamber is a symptom of a shot head gasket. Piston rings cause loss of compression, power, blowby, etc. If all oyur having trouble with is the antifreeze issue, then I wouldn't suspect rings being that they are not in the visinity of the waterjacket.

 

this may sound dumb, but what is pre-detonation, and what does it sound like?

 

pre-detonation is when the fuel/air mixture in the cylinder ignights BEFORE the spark plug fires. (The spark plug is supposed to be the only thing to ignight the air / fuel mixture.) This is bad because the piston is now being forced down on its way up, which robs power among many other problems that other people can elaborate on. What does it sound like - something like a small popcorn machine in your engine compartment on a full sized vehicle. You'll notice the poping mostly on steep hill climbs or other times when you are really pushing the engine. (Towing a trailer uphill with the pedal to the floor would be a good example.) On a DS I'm not sure exactly what it would sound like, but certainly a poping type of sound.

 

Read this

 

Well I took apart my #7995 and my rings were just fine. I couldnt find any reason I had startup smoke. I replaced my valve seals also, the old ones looked fine....as far as I can tell. It gave me a piece of mind to tear into it not to mention get to know the rotax.

So no broken rings here.

 

Add another victim 2004x Model 7995 DOM 8/2003. Top ring let go, piston shattered, head pitted like an acne ridden teenager, cylinder salvagable. How do I get Bomb to step up on this?

 

If you have a good dealer i would talk to them about it very seriously....a dealer always has more power than a single person complaining does. Tell him about all these similar cases.....its kinda late for warrenty on your ds....they might just ignore the problem and say it was your fault.

 

I am not sure it is worth the aggrevation. I am pretty disappointed with the DS 650 reliability overall. This is the second one I have owned that has had some kind of major engine failure. I owned several Polaris and Suzuki quads with zero problems so I am thinking it might be time for a change even though I love the quad when it is not in the shop [img]i/expressions/face-icon-small-sad.gif[/img]

 

I say...get a good engine builder to put a good piston in it a JE or something..go up to like 11.5-1 compression so you get a bit more power but can run 91 octane. If you get a good engine builder to do it you will never have to worry about it again...EVER. But it depends how much damage was caused...you could almost buy a used ds650 for the factory cost on the jug and head and piston.

 

Well, you guys can add another model 7995 to the list! My buddy brought us his DS because of excessive blowby and some loss of power. Well, we did some cleanup and dumped about a gallon of water out of the exhaust (which led us to find out that it had ben submerged, of course). That got it running again and we honestly thought it was going to be alright. As we let it cycle the new oil, there was some noise (which I now know was detonation) and it kept getting worse - then it bent a valve. We're in Springfield, Missouri so Bombs aren't common around here so I had to do some research, leading me to find this forum which I'm finding to be the best website I've ever found! lol! Anyway... I was fortunate enough to go ahead and check out this thread because as soon as we saw that the blowby was still there, I KNEW what was going on. We tore the engine down today and sure enough, the ring was almost completely shattered, part of it was stuck in the top of the piston, there were 3 holes in the piston, the cylinder head was gouged severely (some gouges were as much as 1/16" deep) and all 4 valves were at least slightly bent. I don't know what Bomb parts are in Canada, but down here, we're looking at about $1300 usd for replacement parts! I'm going to call Can-Am to see if there's anything they can do. I doubt it, but I've got nothing to lose! Oh yeah... and the owner's brother bought a DS about 2 weeks before this one. We've got our fingers crossed that it's okay!