Sometimes my '96 XP won't develop full power/rpm

[dannyual767]

BACKGROUND: Bought it non-running with two freeze cracked jugs in January 2012. Got a pair of machined jugs and new WSM pistons (spring 2012) and cleaned carbs. Replumbed with all new fuel lines and running premix at 40:1. Ran OK but had bogging issues. This year, I bought complete rebuild kits (Mikuni) along with new needles and seats (aftermarket.)

After lots of headaches, I finally got the ski to run good with no bogging. I'm stock except for Tau Ceti FAs.

1.5 N&S, 24psi popoff, 145 mains, 72.5 pilots with lows out 1 1/4 turn, high closed on mag side and PTO high out about 1/8 turn.

Took my ski out yesterday after replacing the wear ring with a osdparts.com delrin ring. Works great! Ski ran better than it ever has and I even saw 54.7 on GPS on good but not perfect water.

Prior to that 54.7 mph run, I could tell the engine wasn't developing full power/rpm. Speed was in the low 40's and I was thinking that maybe the RAVEs weren't opening up properly. From a standing start, I punched it a couple of times (no bogging :thumbsup: !) and all of a sudden the engine had top end power and I was exceeding 50 mph. Found some pretty good water and ran my 54.7. Felt like it had some more so I turned around to see if I could top 55mph but the ski only ran 52.7 and it felt like it was "wavering" at the very top. I could tell it didn't have the muscle of the 54.7 run. Tried again and got the same. Even though I knew I shouldn't have pushed it (worried a bit that it might be leaning out at the top end) I tried a third time and it ran a strong 54.0mph. I said "good enough" and didn't do any more top speed runs.

What should I be looking for to fix the problem of the ski not developing full power/rpm? RAVES need cleaning? Something wrong with the water regulator?

 

[manolocross]

Put stock airbox back on. Usually aftermarket air filters( tau ceti) require retune of carbs for a tiny unnoticeable performance gain.

 

[dannyual767]

Thanks for the suggestion, mano. Unfortunately, the ski came with the aftermarket FAs and I don't have the stock air box parts.

 

[CurtisGSX]

The water regulator can leak and cause performance issues. Also could be a stuck rave valve that is not opening and closing properly.

 

[manolocross]

Thanks for the suggestion, mano. Unfortunately, the ski came with the aftermarket FAs and I don't have the stock air box parts.

You can get the parts for cheap from Minnetonka on this forum. Send him a message. Unless your racing skis the stock airbox can flow all the air you need and PROTECT from water intrusion.

 

[Coastiejoe]

I agree with the others.. For some reason when the stock air box is removed it is normally followed by some sort of issues...

Since you are base engine, you need to get the base air box just to see if this is your issue.

 

[dannyual767]

When I made the purchase in Jan 2012, I got two non-running 1996 XPs. Both came with Tau Ceti FAs already installed by a previous owner. Both skis are now running and the other ski doesn't have the problem that I've described in this thread. It runs all the way to the top.

 

[dannyual767]

If I get a chance tomorrow, I'll take the RAVEs apart and see if they look gunked up.

I'll have to take a look at the water regulator as well. Would a bad water regulator reduce top speed by 10+mph??

 

[CurtisGSX]

Would a bad water regulator reduce top speed by 10+mph??

Yes if it is leaking bad enough. Had it happen on my ski earlier in the year. It is easy to check. Hook your Seadoo up to a hose, take off the seat. Then run it for roughly a minute at low to mid rpm and check for leaks.

 

[dannyual767]

Okay. So I'd just be looking to see if water is leaking out of the plastic water regulator housing while the engine is running on the garden hose?

 

[CurtisGSX]

Okay. So I'd just be looking to see if water is leaking out of the plastic water regulator housing while the engine is running on the garden hose?

Yes, make sure to rev the engine slightly while looking for any leaks. Mine would not leak at idle but once at mid rpm would shoot out a steady stream.

 

[dannyual767]

I might have a chance to do that tomorrow and if so, I'll post what I see.

 

[racerxxx]

Yes, make sure to rev the engine slightly while looking for any leaks. Mine would not leak at idle but once at mid rpm would shoot out a steady stream.

I might have a chance to do that tomorrow and if so, I'll post what I see.

Here's what he is talking about. Video courtesy of [MENTION=58005]Pale Rider[/MENTION]
http://www.seadooforum.com/showthre...eel-Swell-quot&p=275075&viewfull=1#post275075

[video=youtube;aldY0Nh_aC0]http://www.youtube.com/watch?feature=player_detailpage&v=aldY0Nh_aC0[/video]

 

[Matt Braley]

And you don't need to pull raves to check them. You can check both in 10 seconds. I just take both thumbs and push the retaining clip off(keeping the spring from shooting out of coarse) and then slide them up and down. You will know for sure right then if they are stuck or sticky. Look the rubber bellows over for any tears or leaks.

 

[dannyual767]

racer, thank you very much for that video. Even though Curtis said that I'd have to rev the engine up to mid rpm, I still didn't realize how much he really meant. I'll rev it up and watch my water regulator real close.

Matt, thank you for the RAVE checking information. That'll save me a bunch of time. I'll do it later today and post back what I find.

 

[dannyual767]

I ran the engine on the hose and reved it up looking for any leaking water from the water regulator. There was no leaking water. Just for curiosity's sake, I removed the small hose from the exhaust pipe. The small hose that comes from the water regulator. I then ran the engine and reved it up and looked for water coming out of the small hose. I couldn't ever get any water to come out of it. Perhaps the way water enters the cooling system via the garden hose is causing no water to flow out of the small water injection hose.

I checked both RAVEs like Matt suggested and they both seemed to move easily and smoothly. That being said, they are leaking some oil but the plastic pistons were in good shape and the bellows looked okay but they were oily and I wouldn't have been able to see a pinhole in them (assuming there was one.)

 

[racerxxx]

Yes thinking of it that inlet for the regulator comes from the pump. Probably going to have to back it in the water on the trailer. Our disconnect the line from the pump and adapt that to a garden hose, possibly.

Sent from my SGH-T889 using Tapatalk 2

 

[dannyual767]

Update


Yesterday, I installed brand new OEM Sea Doo RAVEs and housings. I bought them brand new from an ebay seller. I paid less for brand new OEM than what I would've paid for aftermarket parts.

Anyway, I took measurements of the new parts and the old parts. My old parts were plenty worn out with valve stem to housing clearance at .009"! The new parts have clearance of .003". I think my RAVEs will no longer be leaking oil. I did file the ends of the valves for my oversized pistons. Both bellows looked good and so did the o-rings.

Did another compression check before I started the ski up with the new parts. Cold, throttle wide open, plugs out and fully charged battery-135psi both holes. A little more would be better but at least they're consistent.

Planning to take the ski back out tomorrow and see if the new parts make a difference in the upper end power. Maybe I'll run it on the trailer with the seat off to see if that water valve is leaking.

 

[dannyual767]

Happy Halloween to all.

I finally got the ski out today. Bright sunshine, wind not too strong and temps right around 80° F. Ski ran great. Developed full power from the very beginning so the new RAVEs probably did the trick. I'm pretty happy with the ski. Lots of power and a ton of fun!

I haven't mentioned it in this thread but this ski is pretty hard to start after it's been run and then shut down for 10 mins. Even after all the carb rebuilding it's still kinda hard to start. I have to give it some throttle to get it to start. It's easy for me but if anyone else is on it, they don't know what to do to start the ski.

 

[kicker]

Glad to hear you got it running better, nice job.

With the compression at 135 ish, it would be normal for it to be a little hard to start. The fuel and air will not be flowing efficiently through the cylinders with a low compression. If it is running good once started I don't think you will want to start making adjustment to try and get it to start easier. Unless you want to bump up your idle a bit, normally it should be at 1500rpm

 

[Minnetonka4me]

Just a tip with the water regulator...that springs are known to crack in half, so if you havent pulled the top off I suggest taking a look.

It works much like a Rave, just with water pressure instead of air.

I also like to pull it apart and make sure there isnt a hole. If not, fill the rub mark with some RTV, and either trim off the tabs on the small clamp, or take the clamp off and replace it with a quality skinny Ziptie.

 

[Matt Braley]

Danny those hard hot starts sound like leaky needle and seats to me.

 

[dannyual767]

Danny those hard hot starts sound like leaky needle and seats to me.

That's exactly what I thought, Matt. When I did my full rebuild of both carbs with a rebuild kit from osdparts.com along with new needles and seats, I thought the hard starting would be a thing of the past. Not so. I'm still suffering from it :facepalm: .

 

[dannyual767]

Glad to hear you got it running better, nice job.

With the compression at 135 ish, it would be normal for it to be a little hard to start. The fuel and air will not be flowing efficiently through the cylinders with a low compression. If it is running good once started I don't think you will want to start making adjustment to try and get it to start easier. Unless you want to bump up your idle a bit, normally it should be at 1500rpm

My other XP has about 5psi more compression in each hole and it doesn't have the hard start problem. But then again, maybe that 5psi extra is what is required.

You're right. The ski runs too good once its started for me to do too much more messing around with it .

 

[dannyual767]

Just a tip with the water regulator...that springs are known to crack in half, so if you havent pulled the top off I suggest taking a look.

It works much like a Rave, just with water pressure instead of air.

I also like to pull it apart and make sure there isnt a hole. If not, fill the rub mark with some RTV, and either trim off the tabs on the small clamp, or take the clamp off and replace it with a quality skinny Ziptie.

I haven't looked at the insides of it since last summer (2012) because I lost the metal retaining clip and I had to do a hack job with nylon cable ties to secure the plastic cap. Its nice and snug and has held for two summers but you're right, I need to take a look in there to make sure the spring is good. I just so happen to have a brand new OEM spring. Last summer, my other XP had a broken spring so I wisely ordered up two from my local dealer who is now out of business.