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is 120 compression bad on a 2000 seadoo GTX 1000?

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arctyler

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im looking at a 2000 seadoo GTX 1000, and the guy said he tested it and it has 120 compression so i told him that was low and then he started getting all mad about somthing? saying he has never seen a small engine go more than 120, and then he said he wasnt interested in selling it anymore, like he knows that it has problems, it sounds kind of fishy to me, what do you guys think? he said it was rebuilt by harts motorsports in mayfield, ny last season and 120 compression is fine, i think i might give harts a call later and ask them about it, but what do you guys think?
 
Without even seeing the ski that is not a guy you want to buy anything from. Not the way to sell a ski or treat a potential buyer. The compression on a fresh 951 should be about 135 but compression gauges can have questionable accuracy.
 
thats what i was saying to myself, like dont act like a Dbag to a buyer, all i wanted to know if that was normal and he starts flipping?
 
Comp

My gauge only shows 120 on my 2002 GTX with only 30 hrs on it... runs solid. same gauge shows 110 on a fresh rebuilt engine... engine also runs solid. I think some of these gauges are not very accurate...
 
soooooooooooo...anytime SABRE tells you that his compression is at 110 then you just add 40 and your where you should be!!!!
 
Well it kinda depends on what your looking for, if you're looking for a cruiser, a larger ski a GTX, if you're looking for a really fun ski for jumping wake a mid to late 90's X4 hull, ie 96XP, a 96-97GSX in a compromise between the two.

Personally the 96GSX is my favorite ski, but that's just me.

Lou

Added: Actually the 97XP has a 787 (110HP) and for it's body size has plenty of power, not my favorite ski, but still a good choice.
 
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another factor is if you be riding single or with a passenger. Like Lou said the GSX is loads of fun but not real stable at slow speed with a passenger. very stable if riding single though.
 
I thought the Gsx was supposed to be a "real" 2 passenger ski between the x4 size "2 seaters" and the 3 seater cruisers like the gtx and gti?
 
Actually I find the GSX real stable with two people, I haven't flipped it yet, however this is the first full season I've owned it. It's very stable compared to my 95XP 800.

Lou
 
i've never flipped it but have been dumped off 3 times at idle speed. if you turn too hard or someone leans the wrong way
 
I agree. an 800 XP or SPX is a fun ski. BUT.. realistically... it's for a single rider. Once you get a second person on it... it's not stable.

On top of the seller sounding like a Dbag... as Lou said... the 951 isn't the best engine that seadoo used. AND... that would also make it a Di ski. The Di system is great, when it's working. But, when you have an issue... it's hard to diagnose, and expensive to fix.


I would pass on it... and not even think about looking again.

As far as the 120 psi thing......

Yes, a fresh 951 should be 135 psi. BUT, I've seen a bunch of "Fresh" rebuilds that only show 120/125. I think the rebuild shops are running the base gasket thick, and in turn, it drops the compression, and makes the engine a little more reliable. But... it's also loosing 10 hp because if it.

As far as the guy selling it... these Rotax engines aren't "Small Engines". They put out as much HP as a compact car... and they make as much HP/Ltr as any Super Car made. (Ferrari, Bugatti, Zonda, etc) and on the 800 and smaller engines... 150 psi is spec. So, he doesn't know Rotax.
 
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I think the rebuild shops are running the base gasket thick, and in turn, it drops the compression, and makes the engine a little more reliable

Tony, can you explain the above for us novices? I understand the thicker gasket drops the compression. Does it make the engine more reliable because it is running a little cooler (just guessing) ? Thanks!
 
Tony, can you explain the above for us novices? I understand the thicker gasket drops the compression. Does it make the engine more reliable because it is running a little cooler (just guessing) ? Thanks!

basically that's it. lower compression means a bit less power, so a bit less stress on the lower end, and a bit less risk of a slightly lean condition burning a hole in a piston or detonation cracking a ring land.
 
Yep... what he said.

The very first 951 engines ate them selves in only a few hours run time. Basically... they were running the same 150 PSI static compression that all the other Rotax engines did. Because it was such a failure... they dropped the compression, changed the port timing, and re-designed the squash band area. (and changed the color of the engine to silver)

Oh... after a few re-designs... they did bring back the 165 hp version again for 2 years in the RXX. But... since they released them for the racing community... they didn't have to warranty them.
 
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