my new to me toy

[jammin777]

finally got one! a 99 gsx rfi picked it up with trailer last week. the motor has 130 psi compression which to me is not so good (pulled the head off and mag cylinder has some scratches i've been thinking of having ses rebuild it for me with the 2 year warranty. every thing else works on it and the top of the hull is in pretty good shape, just need a little buffing but not bad. however it has been beached so i am going to repair the bottom and spray with gel coat. (found a web sight that sells seadoo colors) the bottom is really not that bad but has a little glass showing but shouldn't be too hard to repair. while the engine is out i'm going to pull and flush the gas and oil tanks and clean the bilge, send the injectors out to have them checked/reconditioned and test all sensors and such and replace as necessary. the impeller and wear ring look great. looking forward to a winter simi restore project and have it ready and hopefully reliable ski for next season.

 

[Coastiejoe]

Congrats on the purchase.

Any chance of doing what you NEED to do so you can use it this year still?

 

[Dr Honda]

130 is low on the 800 engine... but you are still in the range of "Error".


If you tested it before any riding was done... you may want to run the engine a little. (but do the test cool) Then... make sure you have the throttle open. And finally, make sure the gauge is OK.

If it is truly low... then, since yo caught it before a melt-down happened... you could just replace the pistons, and rings, and get a few more years out of it. (assuming the cyl's are still in spec) Normally, we tell people to not do a top end on an old crank, but that's after the top has scattered, and thrown metal chunks into the lower. it would cost you less than $200 to "Freshen up" the top, and get a few season out of it, before needing a rebuild.

 

[jammin777]

my old gauge it read 130 psi both cylinders wot cold, then i bought a new gauge from auto zone and read 100 psi, not sure which one to believe. i kinda thought of buying a piston kit and boring out the jugs but then i think just get a new engine and be done with it and do all i can to make sure i have no issues next season. the ski has 160 hours on it. what do you think. is it a crap shoot? i don't want issues next summer to ruin my riding season, its time to have fun! lol!

 

[Spimothy Leary]

its always a bit of a crapshoot, but $300 vs $1,000 + shipping, (+ delays) i'd take the chance myself. Its almost september so I'd personally say, do the minimum, run it thru the fall, then if it runs good, go into the spring with a positive attitude that it will hold up.

 

[jammin777]

if i do just the top end, is there any way to help me decide such as smooth movement of the rods and check for side ways movement without splitting the case? if i knew for sure i can get a few more seasons out of it, then i may consider just the top end, but if a crap shoot then i will just go for the whole rebuild. question though, are the crank and rod bearings roller/needle or babit like a car?
hmmm, i like the money savings but don't want to wreck my season next year. lol!
also can the crank seals be replaced without splitting the case?
my thinking is that if i want to turn my seadoo upside down to repair the bottom of the hull, i would need to pull the engine out anyhow and drain/remove the tanks to lighten it up. any idea of how much a half bare gsx hull weighs? thanks...

 

[Dr Honda]

All 2 strokes will have roller bearings. Even a lowly weed-eater is on rollers. The only 2-strokes that can get away with a bronze bearing is small model engines. But, they run 20% oil !!!!! (that's why glow engines are so messy) Yes... if you do your math right... that's a 5:1 ratio.


Solid bearings (for the most part) are in engines with an oil pump, and run pressure. In an ideal world... you put a pressurized pillow of oil on the journal, and the bearing never touches it.



I wouldn't do a full "Top-end". If the cyls are still in spec... just put in 2 new pistons, with rings... at the stock size. If you have enough wear in the cyl, that they need machined... I would do a full rebuild.

 

[CurtisGSX]

my old gauge it read 130 psi both cylinders wot cold, then i bought a new gauge from auto zone and read 100 psi, not sure which one to believe.

If both cylinders really are around 100 psi the engine would probably not start. If it runs fine then I would definitely not trust that reading.

 

[jammin777]

I wouldn't do a full "Top-end". If the cyls are still in spec... just put in 2 new pistons, with rings... at the stock size. If you have enough wear in the cyl, that they need machined... I would do a full rebuild.

thanks! that's the answer i was looking for. like i said, the mag cylinder has some scratches and has me worried. i kinda figured that i wouldn't get away with a band aid. so i believe a full rebuild is in order, probably ses as i don't really need it right away plus they have the best price for a quality product and great warranty. that will give me time to get the ski in top condition for next year.
i may get it running just to see if its putting out the voltage it needs as well as testing other items before i tear it down.
btw, what is the best way to ck the injectors to make sure the spray pattern is correct? can i do it by cranking the motor with the injectors out with spark plugs on their grounding post? thanks again guys for the very helpful advise! this forum is top notch!

 

[Sportster-2001-951C-Stock]

I have some antique 2 stroke engines, and they have bronze crank bushings with babitted type rod bearings. I run a 16:1 premix in these.

Modern 2 stroke engines use roller bearings, the bottom end still needs oil though!