2001 GTX Millennium Edition 951 engine low compression

[colrhino]

Greetings All,
FNG from Atlanta here. I have had this ski for four years. Bought it used of course. I replaced the fuel lines, rebuilt the carbs, when I first got it. It has run great since, just a new battery twice. I do have some gauge issues, fixed the gas gauge from the info on this forum- thanks! Put it in the water this year after de-winterizing it, difficult to start. I pulled the plugs to look at them, decided on a whim to do a compression test. 120 for the front, 40 psi for the rear. Damn! It never has run low on oil, oil consumption was about 3/4 of a tank of oil to a tank or so of gas normally. WTH happened? A boat mechanic buddy says he hears a knock- the non-driven piston, or the crankshaft? So how do I know if I just need to rebuild the top end, or do a complete overhaul? He says buy a four stroke; junk this one. I used to race motocross in the 70's, we only had two strokes back then, I used to do all my top end work etc myself. I want to fix this one! But I do admit that I have limited experience with PWC's. So how do I proceed? I know about the SBT and Full Bore options, what way would you proceed? Thanks !


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[jhjesse]

JMHO
I personally would not do just a top end rebuild on a 14year old crank. Added pressure to old crank bearings could cause a failure.

 

[SabrToothSqrl]

Yea, with a 14 year old engine it's going to be an all or nothing. Even if you could do just the top end (assuming the crank is fine), you'll be back to broken in a week...

SES, SBT, etc, find one you like and just swap it w/a warranty. The tools and experience needed to rebuild it your self minus the warranty make the engine swap the way to go for most people...

 

[Coastiejoe]

I tend to agree with the above...

If you fix the top I would suspect the bottom will follow behind. The concern is, even if you were ok with that, by the time you doa top end and then a bottom end, you could likely buy a rebuilt unit that all kinds of new parts instead of just the pistons, crank, and bearing..

 

[colrhino]

Looks like it's beginning to become a majority here... And I understand the logic. So now let's get really controversial here, and let me ask for more specific advice- which motor mfg'r is the way to go? What is generally considered the "best" bang for the buck? I've heard of SES, SBT, Full Bore....... Who else is a player in the "send in your core for a replacement engine" field? Thanks again for all your comments and suggestions!


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[Dr Honda]

the 951 engine has a short life as it is. If you do a top... the old crank will give out soon. So... it's a waste to just do the top.



FYI... in the 70's... we didn't just have 2 stroke MX bikes. But they did generaly race their own class in MX, but in SCORE/Desert, we would get mixed together.

Yamaha: YZ/MX/IT = 2 stroke, TT/XT 4 stroke
Honda: CR = 2 stroke, XL/XR 4 stroke
Suzuki: PE/RM 2 stroke, DR 4 stroke
Kawasaki: KX/KDX 2 stroke, KL/KLR 4 stroke.



And that's just the one's I remember off the top of my head. (lol)

 

[colrhino]

Haha, Dr Honda, touché my friend, you are correct, I even had an XR at one time.... I really meant back then the only real players in the MX world were the high revving "on the pipe" two strokes! So what about the replacement engine- any recommendations as to which one to purchase??


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[SabrToothSqrl]

I moved past the whole 2 v 4 stroke thing when I bought my Tesla

Regardless of shop, you're looking around $1500-2k to get back on the water.

If 2k would go further to buying a working 4 stroke, that's also your choice. If you were in PA, I'd offer $750 cash for the ski + trailer today, as is, especially considering I have a working 951 ready to drop into a ski...

 

[mikidymac]

If you want to be back on the water this summer your only option is factory Seadoo rebuild or SBT.
SES and FullBore will not have your engine back before summer is gone because this is their busy season.

 

[colrhino]

Same price between those two, or is the SeaDoo factory rebuild more expensive (I'd guess?) ??


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[stout890]

i have a 2000 y2k edition RX-di also with low compression. i don't know the compression numbers are though, but last time it ran in 2007 it was still doing 50+. but you guys say to do a full overhaul since its an old engine? even if it was still running when it was stored? why is that? if the crank bearings are not rusted and roll smooooooth how will higher crank pressures destroy the bearings? if i split the crank case and had the crank work done at a shop it shouldn't be too hard to get running again right? sorry not trying to hijak the thread but we are in the same boat....or pwc lol

 

[colrhino]

Hey stout890, mine was also running when I put it up for the winter. I stored mine in a heated garage all winter also. Fogged it, treated the fuel, the whole nine yards.... Now this year it has low compression when I checked it? I'm befuddled......


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