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Hi:

I bought a 1993 EXT 550 EFI a few weeks ago. I have been reading a lot of reviews on the EXt's on this site and seems the motors do not rate that high for durability. What I am curious about is does the 550 have the same known problems as the 580's? I keep hereing about dropping pistons rings and Intake boots on the 580. So does the 550 have the same problems? My buddie has an older 91 EXt 530 with 9000 miles and hasn't had a problem. Can anybody tell me anything about my sled for reliability and known problems?

Thanks a lot.
 

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I don't know of any repetitive problems w/any of those motors. I did own an '89 EXT ElTigre for about 10 years, and the sled was completely trouble-free...didn't have to spend a dime on it except maintenance. This was the first sled that I really started riding hard on the trails. Wish the ZRT was half as reliable as the old EXT.
 

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The 580 has been known to go through rings faster then most cat engines... i think the general consensus on this topic was about 3000-4000 miles before a piston/ring job was evident.... all engines ca have their problems... there are 50's and 530's out there that also could have needed rings after 3000 miles.... some of it depends on the rider... give me a 550 and i could make it need a ring job real fast... althought the feeling is that the 550 is an almost indestructible engine hence why cat still offers the 550 and as of 2002 the 580 was to become history
 

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We still have one 94 580 EXT and a 93 550 EXT. Neither of the 2 sleds have ever had motor problems. Both have well over 8,000 miles on them as well.
 

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Hi,

I haven't had any problems with my EXT. It is a '91 El Tigre EXT Special 550. I bought it with 7600 miles on it. The previous owner had rebuilt it at 7400 miles (Pretty good for a two-stroke):). He sold it because he had a new ZR 600 sitting next to it. I've put about another 400 or 500 miles on it since I bought it, and It runs great. I really like the sled. Even with so many miles on it the sled is holding up great.

Think Snow!!
 

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Cat has had problems with the 550 pistons. The pin that holds the rings from spinning works it's way in so that the ring can spin until it opens and catches on the exhaust port. Cat has updated the piston 8 times and they finally got it right around 1999. If you have the original pistons in the engine, I would suggest replacing them. Not all the engines will develop this problem but a friend who works for a Cat dealer said that about 1/3 of the 550 engines built before 1999 will spin a ring and take out the cylinder. :thumbsup:
 

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I ran a 90 530 ext for 9000 miles and in stock form it would beat a 91 ext 550. I ended up porting it and putting psi piped on it and got 95-100hp faster than 94 583 formula Z. My brother sold his 90 with 9000 miles on it 4 years ago and I think it's still running.
 
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