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Finally pulled the trigger - '97 and '00 GTX!

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dean.mohr

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Hey guys!
I posted a few weeks back about some skis I was trying to buy and naturally, my first 3 tries all fell through/fell on deaf ears. However, a friend of a friend happened to buy some brand new jet skis and sold me his 97 and 00 GTXs on a trailer for $2,500!

This post is going to focus on the '97, since currently the '00 is waiting on a new pump (ran without oil for a while, cannot get the impeller off the shaft :mad:). It is also worth mentioning that both are premixed and have been since long before I owned them.

I have already done a jet pump service on the '97; everything checked out pretty good on that end. It will need a new battery, but that's not a big deal. I did find a water jacket leak on the exhaust and got that welded up, so we are all good there. (One of) the previous owner(s) had already gone through and replaced every fuel line at some point. The ski has 275 hours on it, but I believe it has had a rebuild. It fires up very easily (when the battery holds a charge) and runs shockingly quiet compared to the 951 in the '00.

The only real problem I have is a bog between 3500 and 5000 rpm. On the water, under partial OR full throttle, it will reach about 3500-4000 rpm, then struggle, then rip like a bat out of hell from 5000 to 7100 and cruise at an indicated 53-56 on smooth water. My understanding is that it most likely wouldn't be the low or high speed screws, as those correlate more to throttle position rather than RPM, and this is always in that same RPM range. After a little reading this morning, it seems like possibly a RAVE valve problem.

Anyone have any suggestions or experience with this?
 
Pull the raves off and check them out, possibly they are just really gummed up.

Also confirm if they are slotted raves or flat blade.
 
Yanno, I JUST found a few other posts indicating the RAVE valves as the likely culprit. I will be doing this tonight! With any luck I'll be back out on the water tonight.
 
You also need to make sure there is still oil for the rotary valve shaft in the 1997. Either they left the oil tank or looped the hose and you still need to keep API-TC oil in it never TCW rated oil.

Also for premix you need to be using only full synthetic API-TC oil.
 
Looped the hose as in basically closed the case? Either way, it obviously has oil in it now, but I will be checking it tonight. I see there is a "how-to" on changing the rotary shaft oil for the 951 engine; is there anything similar for the 787? (The oil I have is Bombardier XPS syn, so I'm good there.)
 
No, the 951 doesn't have a rotary shaft but it has a balancer shaft that the oil should be changed on.

On the 787 the rotary shaft doesn't need to be changed just make sure there is plenty in the hoses.
 
It changes when the rave valves open. More spring pressure means they open later. It is more of a personal preference thing and you will not damage anything playing with them. It basically tunes when the power "hits" in the pm range.
 
Well lo and behold, the valves were disgusting - lots of caked on buildup and plenty of oily mess. Spent a while cleaning them and got them reinstalled and set as mentioned above (three clocks from fully tightened) and the thing was 10 times worse! It would big at about 3500, then jump to 5000 where it would stay for up to 5 seconds. I tried backing them way out and that made it almost unusable. Tightening them all the way in put it back to about where it was prior to the cleaning in terms of performance. Prior to cleaning, they were probably most of the way out.

One bright side is I did seem to gain an mph or two on the top end, maxing at a consistent indicated 54 mph.

Is my next step to pull the carbs off and start cleaning and adjusting?
 
Make sure new plugs and that the carbs LS =1, HS=mag 0 pto=1/2

I didn't change the plugs, but they appear to be all but brand new (not wet, not even any blackening of the tips). I have some others that I may throw in next time I'm out just to fully eliminate that, as well.

I think my next move is to pull the carbs off and try to clean them and reset the screws back to stock positions.
 
If you haven't been through the carbs with new parts that is definitely where I would go. I also replace the fuel strainer and filters when I do it.
 
What plugs are in it? Make sure they are the correct ones. These engines use resister plugs and wrong or bad plugs can cause noticeable performance issues.
 
If you haven't been through the carbs with new parts that is definitely where I would go. I also replace the fuel strainer and filters when I do it.

I was hoping to avoid having to tear into the carbs, but I guess that's next. The main fuel filter was already replaced, but not the one inside the carb(s).

What plugs are in it? Make sure they are the correct ones. These engines use resister plugs and wrong or bad plugs can cause noticeable performance issues.

It has the correct BR8ES plugs.
 
So I had a realization today... while cleaning the rave valves on the 2000, I found that there are springs inside the bellows. When installed fully, you can depress the top of the bellow/valve and it will pop back up (open). On my 787, there are no springs, and the valve pretty much sits shut the whole time. When pushing on the top of it, it doesn't spring back up at all. This would make sense why it would hang at 4 or 5000 rpm, then come to life when the valve opens.

Now the question is, why doesn't the valve pop up on the 787? According to the parts manual, there is no spring in the bellow.
 
On the 787 the rave valve will sit closed (in down position). There should be springs on top of the plastic cap that threads onto the stem of the guillotine valve. The bellows attach to this plastic cap. Springs go between this and the black top with red adjuster. If you take the black top with red adjuster off, the valve will stay in down position. If you pull up on it with engine off the bellows will pull it back down to closed position.
 
Yup, that it does. Seems backwards to me, but I did look at the drawing and found there is no spring.

On the water, you can kind of feather the throttle through that midrange to get it through, otherwise you just hold it and after a few seconds it realizes you're supposed to be going 50+ and jumps to 7000 rpm.

I am on vacation most of this week, but may try to get the carbs off before I leave.
 
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