Total Newbie 1997 GTX questions

[waltersbg]

Hello All:

I have been a Sea-Doo owner for one whole day! I have riding experience on jet skis, but no owning experience. Same with boats in general. Also, the only 2-stroke engines I've owned are a chainsaw and a brush cutter.

We hope that this ski (1997 GTX with Rotax 787 engine) is in as good condition and runs as well as the previous owner says. The owner said that he took it to a Sea-Doo repair place last season due to some sluggishness and they cleaned or replaced the rave valves (not sure which) and that fixed the problem. The engine does have 182 hours on it, but they tested and marked the compression numbers on the engine at that time -- 155 and 160, which sounded great to me. I also did things like inspecting the impellor, looking for signs of fiberglass work, and looking for signs of excessive heat in the engine compartment. Overall, it seemed in very good shape. It started easily and sounded good to me.

But...there are some things that I'll need to address before too long. One is that the fuel gauge is completely blank, regardless of the actual fuel level. There's a lot of help out there for debugging/fixing that.

Another minor issue is what kind of gas to use. The previous owner (who has owned this 1997 GTX since 2006) says that he has always used premium gas. I'll keep doing that if it is a good idea or if it helps to stick with what has been working.

My main question/concern is about the oil that he used and that I should use. The previous owner has several jet skis and he uses West Marine Premium TCW-3 oil in them all. However, my reading has told me that TCW-3 is one type of oil that I DO NOT want to use in this engine! But, he's been doing it for 6 years and the engine *seems* to be healthy. Maybe this oil is part of the reason why his rave valves were having trouble?

I have no real problem changing over to using API TC or even XP-S oil (which is easy to say when I haven't actually seen how much they cost!). But, I've read that one thing you MUST NOT DO is to mix different oil types in the reservoir. But, how would I switch from the "bad" oil he has been using (TCW-3) to the "good" oil I should be using (API TC or XP-S) without mixing them? I can't run the reservoir dry, like I would with gas. Do I need to go so far as to replace the reservoir and filter and then start using the right oil? I know that a lot of 2-stroke owners have completely removed the oil injection system but I was hoping to avoid going that route as it will be much easier for my family to not have to premix.

Thanks for any help you can give. I'd say you can't believe how excited we are to get out there on OUR jet ski, but I imagine you can believe it because you've all been there yourselves!

Thanks,
Mike

 

[Dr Honda]

Welcome, and congrats on the new toy.

Here's the deal on the oil...........


TC-w3 isn't an instant death. It's a slow death. Also... since he owns other skis... it may not have been run very much on that oil. AND... the West Marine Premium is a very good oil.


TC-w3 oils were never designed to support the hp levels of a PWC engine. Also... it was not designed for power valve engines. It very well could have been the prob with the RAVE valves. But, the loss of power isn't good.


As you already know... it's not good to mix 2-stroke oils. Sometimes very bad things happen. If it was my ski... I would drain the system., by removing the hose at the injection pump, and at the lower rotary valve feed. Let it drain, and drip overnight. Then... replace the filter in the injection hose... hook it back up, and refill the tank with a synthetic API-TC oil. (whatever brand you like) Oh... make sure the feed hose going to the injection pump is bled clean of any air.

 

[waltersbg]

Thank you very much, Dr. Honda, for the quick and thorough response!

In thinking about draining the oil, the thing that confuses me most is how to get a pan of some sort down into the hull to catch the oil. Everything seems so cramped and it seems like it'll be somewhat challenging to just pull off the right hoses, let alone catch the oil. Others have done it, certainly, so I'll look at it and figure it out. I have a shop manual (which tells me how to bleed the feed line) and parts diagrams which should help me identify all the right parts and hopefully how to get the job done without a mess.

I know that oil choices are a source of Great Debate, but I think for a variety of reasons I'm going to try the Quicksilver 2-cycle PWC oil. It seems to meet/exceed API-TC and it is readily available for me. The thing I can't decide is whether I should get their full synthetic or their synthetic blend. I know this is all part of the Great Debate and I've been swayed both ways. Decisions, decisions.

Speaking of decisions, do you have any opinion on the use (or not) of premium gas in this engine? The manual says "regular unleaded" of octane 87 or higher but, as I said, the previous owner always used premium. I don't need every last mph out of this thing, but I want good performance and, most importantly, to get as many more hours out of it as I can. What is the main effect of choosing premium over regular?

Thanks,
Mike