96 XP hitting what sounds like rev limiter between 4-5k rpm when cold

[tingraham]

Hi all,

I recently became a proud owner of my first x4. I am having a bit of a problem where it rips pretty good but for about the first 20 minutes of riding it gets hung up between 4000 to 5000 RPM (according to the TTO tach I added to make sure it wasn't actually hitting the limiter while cavitating or something). It slowly does it less as the 20 minutes or so of riding takes place. If you nail a wave and get the impeller out of the water a little it will allow it to blow past this limit and as long as you keep it above that rpm it'll keep screaming along. As soon as it breaks through this block it shreds like a raped ape. After those 20 minutes of warming up it pretty much completely goes away. If you let it sit for 15 minutes or so off it will start doing it again until it warms back up.

I am very familiar with carb issues on these (as most of us 787 owners are) so it doesn't have that bog feel that you usually get with that. It feels exactly like a rev limiter. I had the carbs off and made sure everything was good to go and up to spec anyway.

Things I have tried are:
new plugs (BR8ES of course)
trimmed both ends of the wires (anyone ever have to completely replace their wires because of issues?)
checked for AC voltage or too high DC voltage coming to the battery, passed the tests
tried pulling the red wire off the regulator just in case, zero change
150 compression on the money on both cylinders

Some random brainstorms. Has anyone had cavitation from the carbon seal that will stop the motor from hitting the max rpm limiter? I would find it very hard to believe that it is the carbon seal just because the consistency of the RPMs that it is being limited to but I'm reaching for ideas.

The coil appears to be newer, has anyone had this kind of issues with a coil or do they usually just go from spark to no spark?

Going to check the resistance of the pickup coil when I get a chance tomorrow probably, see what that comes in at.

Please throw out any ideas you may have. Thanks guys!

 

[manolocross]

Your rave valves might be gummed up and stuck. As the heat builds it softens the carbon deposits and allows them to open. Pull them and clean them. Try it then report back. Just make sure to put them back in the SAME ORIENTATION! Very important!!!!

 

[tingraham]

Well that's gotta be some kind of a record. It never is this easy! I just went out and popped of the rave caps, guess what wasn't there? The friggin spring on one of them! Along with that, the valve blade was completely unscrewed from the diaphragm. Took it out and nothing looks damaged and really wasn't all that dirty but I cleaned them all up and made them all pretty. Luckily, I had an extra spring so she's all back together and ready for a test drive. If I have to guess, I would say that will solve my troubles!

thanks a bunch!

 

[manolocross]

A great running seadoo is a beautiful thing no matter what year or model it is....[emoji41]

 

[1983]

Nice!

I wish they were all that easy.

I had one recently where the black plastic rave piston had stripped out so it was just sitting on top of blade. Helped top end RPMs a ton.


Rob

Well that's gotta be some kind of a record. It never is this easy! I just went out and popped of the rave caps, guess what wasn't there? The friggin spring on one of them! Along with that, the valve blade was completely unscrewed from the diaphragm. Took it out and nothing looks damaged and really wasn't all that dirty but I cleaned them all up and made them all pretty. Luckily, I had an extra spring so she's all back together and ready for a test drive. If I have to guess, I would say that will solve my troubles!

thanks a bunch!

 

[tingraham]

Well, as I said in my previous post "it never is this easy"... yeah, it isn't. The darn thing is still doing the exact same thing. If anyone has any further ideas, I am all ears!

thanks!

 

[Matt Braley]

You say "the coil appears to be newer". It's a pain pushing those wires back in there and it's hard to get it right. I'd look that area over.

I'm also suspect of the water regulator. I'd crack it open and see if the bellow is torn/split. That's pretty common and it will mess with performance like that.

Have you run it with the seat off looking for leaks? The welch plug on the bottom of the pipe like to give out and spray water.

There is an update in the service manual for 97GSX raves that have this symptom. I know that's not your ski so it's a long shot that the raves have been swapped but I thought I'd mention it.

 

[tingraham]

I had the wires out when I trimmed them and put them back in, the clip is a little broken but seems to be keeping them wedged in pretty good. I'll have to order one from OSDparts.

I will pull the water regulator apart and investigate next.

I have not run the sky without seat, I know it doesn't get barely any water in it in the course of an hour ride or so but maybe the bailers are actually working...

As far as the raves, I noticed these aren't slotted when I had them out, is this normal for the 96 motors? I do have an extra set of slotted ones from a 97 XP in good condition I could throw in it.

Of course you always second guess yourself with carb issues but I would be shocked if it was such. It appears that it only has Vortex FAs on it and it;s got some pretty large jets in it and the high speed is out pretty far on top of it. They are as follows:

PTO:
Pilot: 75
Main: 152.5
High speed: 1 1/8
Low speed: 1 1/8
Mag:
Pilot: 75
Main: 150
High Speed: 1 1/8
Low speed: 1 1/8

The plugs are showing that it is running quite nice with a light brown so it seems to be running well with this setup but seems like quite a bump up from stock for just having FAs. But from my experience, a too rich or lean setup would just result in a bog, not a consistent RPM limiter type of situation, but who the heck knows, I guess anything is possible.

I feel that whenever I have a problem with these motors it can only be replicated in the water. Makes it much more difficult for trial and error when I live about 15 minutes from the water.

 

[Matt Braley]

Your jetted for a Factory Pipe Spec 1. That's way too much gas for a stock pipe. The 75 lows (up from 70 stock) are enough to take care of the flame arrestors but you should still have 142.5 highs with the needles closed.

 

[tingraham]

Alright, I'll see if I have any extra 142.5 jets laying around. Probably a good test to start would be to run the high screws all the way down and see if there is noticeable difference.

I pulled the water regulator apart, it did have maybe a 4mm crack in part of the diaphragm, surprisingly not where the clamp was sitting. Had an extra laying around so threw that on, we'll see if that helps a bit too.

 

[tingraham]

New discovery - It has a primer kit and the hose completely dry rotted from the fuel feed T that taps into the main fuel feed from the sending unit. so that small line was wide open letting air in. Not sure if this will be problem solved but certainly didn't help at all.

I know this was in one piece about a week ago because the primer was working, it definitely would not work in it's current state lol. Got it buttoned back up. Going to head to the water soon and mess around with the high speed screws too if it is still acting up. I also found 2 142.5 main jets I had on hand so that'll be next step.

 

[Matt Braley]

Sounds like your issues will be sorted soon.

 

[tingraham]

No luck. Still doing the same. I ran the high speed screws all the way in and it seems like the only difference it really made was a bit of a bog when hammering the throttle and then it would get to what looks like a very consistent 5200rpm and just sits there until you hit wake or something to get the impeller to cavitate then it screams along as usual. Max RPM seems to be around 6800-6900 according to the TTO tach.

When it's stuck at the 5200 rpm I can back off the throttle and find a spot that it doesn't make the "bop bop bop bop" rev limiter type of noise while still keeping the RPMs at that 5200 level.

I'm thinking off ordering up parts to do a rebuild on the carbs. I'm wondering about the o rings on the adjustment screws. I wonder if it could pulse air into the stream of gas and make this happen (I'm reaching on this one probably). I neglected to check them when I had the carbs off.

What would you say the pop off should be at with the FAs on there and with the chokes removed? It's at 30 psi now.

 

[Matt Braley]

So the water regulator is fixed and the correct high speed jets are in? Try adjusting the red caps on the RAVEs and the water regulator.

 

[tingraham]

On that test run the smaller high speed jets weren't in yet. I just put them in now so I'll see how it goes tomorrow. Fingers crossed. Water regulator is fixed.

What do you recommend on the rave adjustment? I have them even with the plastic housing currently.

 

[Matt Braley]

That will be fine on the raves. I didn't know you had the same wrong high speed jets in.

 

[tingraham]

Alright, 1st test run today went ok, but was acting strange still but not quite in the same way, seemed fuel related though. I pulled the fuel baffle and checked the filter on that, it looked good. So I pulled the bowl fuel filter out and right away noticed a large O-ring that didn't belong. I don't have the slightest clue as to why it was on there. It was basically right above the filter where it slides on to the housing, definitely somewhat blocking the passage going from the filter to the carbs. Got that all situated and took it back out. It runs much better. Slight hesitation when pegging the throttle so I cracked the high speeds from 1/2 to full turn open. Seemed better but to be sure I tried closing them all the way, for sure was worse. So I took it to 1 1/4 open and it seems very good. Might go to 1 1/2 and try it.

So it is MUCH better at this point BUT it still kind of pops once or twice right around that same RPM I was having issues with. It is very brief and manageable but still slightly annoying. I am hoping maybe it will go away if I take the high speed screw out a hair further.

 

[Matt Braley]

It's a little off because you're a little too rich on the high-speed. The Stocks setting is the needle closed. Open the low-speed needles a little to take out the low-speed bog.

 

[tingraham]

Ok, will do. Thanks!

 

[tingraham]

I am also debating on just spending the $35 and getting the stock airbox setup off ebay and being done with this non-beneficial AF setup. I have stock 70 low speed jets on hand so I could just take it all back to stock if I do that. I suppose I'll see how a final test and tune goes at the water.

 

[tingraham]

Figured I'd give a little update. I decided on just getting the stock airbox and FA on ebay for like $33 which included the bracket and even all the bolts. Couldn't go wrong with that. I also purchased some black 80 gram pop off springs to get the pop off to stock as well as a fancy sbt pop off tester as I have been using a rigged bicycle tire pump. So when I put the black springs in I was only getting about 20 psi, what the heck! Well sure enough, it has friggin size 2.0 needle and seat. On top of that, I found that the pop off pressures on the original setup were a good 8-10 psi different between carbs with the new sbt pop off tester (potential cause for a lot of these strange issues I would think). Threw some 1.5 needles and seats in and the black springs and bam, everything is testing on the money so I reassembled and set all adjustments to stock (0 turns on high, 1 turn on low). Now I await a test drive out on the water. My guess is that it's going to be a very fun test drive this time.

I will report back with results as soon as I get out.

 

[Matt Braley]

I think you got it now. When it's right it's gonna run right.

 

[96spxpos]

It's a little off because you're a little too rich on the high-speed. The Stocks setting is the needle closed. Open the low-speed needles a little to take out the low-speed bog.

Hey [MENTION=51824]Matt Braley[/MENTION] , quick question on this post... I'm in the process of fixing a tiny bog issue on my HX. You said "Open the low-speed needles a little to take out the low-speed bog. " I think I have been doing it the wrong way... I turned the LS screws clockwise (closing?) to correct the low speed bog.. did I do that wrong? When you say open the LS needles, are you referring to counter-clockwise? Doesn't that increase it, making the "bog" worse? I'm under the impression a bog is flooding and hesitation is lean/starvation, is that right?

 

[Matt Braley]

To determine whether it is a lean bog or a rich bog pull the choke out a little bit. If this helps then it's a lien blog and you should open the low speed needles to compensate.

 

[96spxpos]

So I pulled the bowl fuel filter out and right away noticed a large O-ring that didn't belong. I don't have the slightest clue as to why it was on there. It was basically right above the filter where it slides on to the housing, .

Doesn't look like anyone answered to this particular part... But there is supposed to be an O-ring/gasket in there. If it looked like it didn't belong, it may have been stretched, shrunk or dryrotted. Although round, the actual mold of the O-ring is square(meaning the edges of it) at least mine was. not saying its related to your problem, but it is/can be a problem nonetheless. It'll let air in and the ski wont run right. (see pic, notice the square edges).. so as of right now, you completely took that o-ring out of the filter, or did you reseat it/leave it?