99'GTX questions! Thanks.

[moser42]

So how many hours is alot on a 1999 2-stroke(110hp) gtx sea doo?
I think theres about 135 or 140 hours on mine and stills runs good.
Do you just replace the rings after a certain number of hours or just ride till the motor lets go?
Also it is RFI(rotax fuel injection) are there carbs on this motor?

Thanks!!

 

[Jeff Walkowiak]

Re: 99'GTX questions! Thanks.

it's fuel injected no carbs// about 250 hours depending on how you ride// if you beat on it , obviously it won't last as long// if you ride it easy it can last a lot longer// wide open throttle puts a lot more wear on them obviously.
the fuel injected motors are really better on gas than the carb models, but they seem to explode when the do fail, usually due to a bad oil pump and they can not be converted to premix.

 

[moser42]

Re: 99'GTX questions! Thanks.

Thanks for the info Jeff.
Fuel injected is better on gas? This thing drains the gas tank pretty quick!
I guess PWC's in general aren't amazing on gas.
I do not hold it wide open throttle, I was wondering at what speed do sea doos burn the least gas, I usually try to keep it around 1/2 throttle.
Is there any way to prevent oil pump failure?
Why can't they be converted to premix? does it mix 50:1?

Thanks alot!

 

[Jeff Walkowiak]

Re: 99'GTX questions! Thanks.

pwc's suck gas, I used 6000 dollars worth last year,, good thing it is tax deductible as it is part of my business expenses. 2 strokes need the oil to go through the crank case to lube the bearings// fuel injection puts the fuel directly in to the cylinders, unlike a carb that puts the fuel in to the crank case first, the fuel and the oil help to lube the crank bearings, with a di engine there is no fuel going in to the crank case just the oil ,it mixes with the air that goes through the crank case and this makes the lower end of a d i engine more susceptible to bearing failures and blown rods. the pump has a cable that operates it with the throttle, more throttle advances the pump to give more oil, it is called a variable oil pump, it has timing marks on the front , I always advance the pump just a little to give a little extra oil , but if you don't know what you are doing my position is if it ain't broke don't fix it...
unfortunately the d i 2 stroke engines were not known for longevity so use the best oil you can find.

 

[moser42]

Re: 99'GTX questions! Thanks.

Thanks alot for this information!!
6 grand on gas! wow, I go through maybe 2,000 a summer which sucks! but its worth it because sea doos are fun.
Thats make alot of sense, I guess carbs are better in the oiling aspect, but if they get dirty can cause alot of trouble too.
I have been using the SeaDoo 2-stroke synthetic oil and for the price of it, it better be good oil!
I will take your advice on advancing the oil pump a little bit, I like the idea of a little extra oil going in the motor.
Do the rings in these rotax 110hp twins wear out ? Will the seadoo slow down top speed when they wear out.
Also do you know what cc this motor is?

THANKS!!!!

 

[Jeff Walkowiak]

Re: 99'GTX questions! Thanks.

being honest,, I would never own a di 2 stroke,, I had a carb 787 and it ran great till the oil pump fell apart,, one little screw fell off and boom no more engine, I replaced it with a s b t engine and blew one up about every 3 months till the warranty expired, I put the last engine in it and never even used it, I just sold it,, I now avoid 787 and 951 engines totally. rave valves cause problems too. both have raves and both are notorious for snagging rings.
Actually I believe the fuel injected 787 is 130 hp,, the carb engines are 110,,
I won't buy a 2 stroke any more, I put too many hours on a ski,, my 4 tec has 500 hours, I ride 3 days a week nearly all year, and I ride the heck out of a ski, I was out yesterday for 4 hours,, gotta love florida for water related fun but since I own cobra jet steering I make my living with jet ski and jet boat related steering ,it is all part of my job.. I like my job lol.
http://www.youtube.com/watch?v=XPvJHZuk4zw
http://www.youtube.com/watch?v=55ONQ6Vo4v8&feature=user

 

[moser42]

Re: 99'GTX questions! Thanks.

Good vids, looks like alot of fun, Florida must be awesome!
I sure hope my oil pump keeps working.
So SBT are not very good motors?
I can't figure out why my seadoo is losing top speed, it used to hit 50-52mph now it tops out at 44-45mph.
We replaced the impellar and wear-ring, this made no difference.
Thanksss!

 

[Jeff Walkowiak]

Re: 99'GTX questions! Thanks.

that is way too slow for that ski// try running with the seat removed,, obviously be carefull not to flip the ski but if you see a big improvement with top end when you run without the seat,, it indicates you have an exhaust leak,, usually in the short exhaust hose in front of the muffler,, or one of your rave valves are malfunctioning,, those open up around 3500rpm and make the exhaust ports bigger to add power// I have had those get really dirty and stick, I have also had the oring burn and melt the bellows, you will need to check on them they also like to strip the threads on the plastic cap and fail to lift the blade to open the ports.

 

[moser42]

Re: 99'GTX questions! Thanks.

Would I hear an exhaust leak? It doesnt seem to be any louder than usual.
How fast should this ski go?
Thanks

 

[Jeff Walkowiak]

Re: 99'GTX questions! Thanks.

you won't hear it but after running if it leaks you may see exhaust gases in the hull. should be 50+ mph