96 XP blowing exhaust hoses

[hingstin]

I think the flame arrestor shouldn¨t have caused this.
what can it do..? restrict Airflow...? ( hardly) and IF.. it should just run Rich, and that often leads to that engine runs cooler...

OR if wesee it the "other way" that stock air inlet is very "restricted" and the flame arrestor leads to "more Air" the ofcours eengine run a bit Lean, and get hotter....????
I dont know how these Jets have their Air intake system, but at least the 951 have pretty "free" inlet as stock...

But strange if was working OK in beginning, but as Mikidymac said, check carb and jettings, it is a disaster with wrong jettings, especially if it runs lean....

 

[M24per]

I think the flame arrestor shouldn¨t have caused this.
what can it do..? restrict Airflow...? ( hardly) and IF.. it should just run Rich, and that often leads to that engine runs cooler...

OR if wesee it the "other way" that stock air inlet is very "restricted" and the flame arrestor leads to "more Air" the ofcours eengine run a bit Lean, and get hotter....????
I dont know how these Jets have their Air intake system, but at least the 951 have pretty "free" inlet as stock...

But strange if was working OK in beginning, but as Mikidymac said, check carb and jettings, it is a disaster with wrong jettings, especially if it runs lean....

So thats the thing. I also didn’t think the flame arrestor being added to cause this issue. But I haven’t changed anything else but that before I started having the exhaust hoses blow. Obviously I was unaware that the tuned pipe was hard jetted until yesterday, but then again, the ski came with a WRV and even with the wrong fitting I wasn’t blowing exhaust hoses. I don’t know man this is driving me nuts hahaha

 

[mikidymac]

Well if the old WRV wasn't working correctly and the hard jet was doing the regulation then yes, it would not burn the coupler.
With the new WRV it is drying it out like it should but the hard jet is restricting the water even more so it is melting the coupler.

THe screen will restrict the intake just a fraction but it could be enough to make it a little richer which is good. The missing screen would make it lean and hotter. The intake on these will not limit or hurt performance at all.

 

[M24per]

Well if the old WRV wasn't working correctly and the hard jet was doing the regulation then yes, it would not burn the coupler.
With the new WRV it is drying it out like it should but the hard jet is restricting the water even more so it is melting the coupler.

THe screen will restrict the intake just a fraction but it could be enough to make it a little richer which is good. The missing screen would make it lean and hotter. The intake on these will not limit or hurt performance at all.

Gotcha, so the odd thing about this whole thing is that the old WRV come to find out was working, the only thing that I saw that was out of place was the spring was actually taken from a RAVE valve I believe because it had the long spring along with the short little spring on top of it.

Anyway, I’m planning to rebuild the carbs with Mikuni parts for peace of mind given that whoever was messing with this ski probably also rejetted the carbs as well like you mentioned before. What parts should I need to bring this 96 xp carbs back to stock? I’m not super familiar with the jetting and all that…

 

[mikidymac]

Verify the jets.
For rebuild parts the easiest is "Back to Stock" kits from OSD Seadoo.

 

[M24per]

Verify the jets.
For rebuild parts the easiest is "Back to Stock" kits from OSD Seadoo.

Will do. Do I need to do anything different living above 4,700 ft above sea level? The highest octane level I’m able to find here is 91 non ethanol at the pumps… I know compression is a factor and all so I just wanna make sure I have my bases covered.

 

[mikidymac]

Your ski only uses 87 octane at sea level. Go up and you need less octane.

We run our sea level skis at 5,600' at least once every year and don't change jetting. They are low on power but still run good enough and don't foul plugs.

 

[M24per]

Your ski only uses 87 octane at sea level. Go up and you need less octane.

We run our sea level skis at 5,600' at least once every year and don't change jetting. They are low on power but still run good enough and don't foul plugs.

Woah so you’re saying I’m actually supposed to be using 85 non ethanol? I’ve been putting in 91 this entire time lol

 

[mikidymac]

Well 87 octane at sea level is what’s required.

We can’t get non-ethanol here in California and I haven’t had a single issue with it in anything so I’m not worried about it or part of the anti-ethanol crowd.

 

[MAL]

Well 87 octane at sea level is what’s required.

We can’t get non-ethanol here in California and I haven’t had a single issue with it in anything so I’m not worried about it or part of the anti-ethanol crowd.

Are all 90's era Seadoo's supposed to be running 87 octane?

 

[mikidymac]

Are all 90's era Seadoo's supposed to be running 87 octane?

Yes, the only ones that require 91 octane are the Di 951.

 

[seadoosnipe]

I have nothing but 787’s in my shop. I started in this forum as a moderator in the early 2000’s. I just rebuilt a 787 for my 87 GTX. It will hit 60 top end. Why go 4-TEC, when I only have one sensor and no BUDS software to worry about.

These engines are really straight forward. After reading through, I kept waiting on a reply involved jetting, or outside ur cooling system, cause from what I’ve read, you’ve got that covered. It’s really simple, water comes in at top head plate, runs through a row of baffles, then into your tuned pipe, down into the jugs, then up and out through that head plate.

These Mikuni’s have several jet sizes, for different operation, so yes, that should be looked at. Also, since it appears your cooling system is correct, albeit you have the calibrated fitting size right (but even that should not cause that problem) I’d be looking at your synchronization. You don’t mention a plug read. If your sync is out, or your running lean, it can cause added heat. Also, make sure you’re not sucking air at the base of the carbs. He did say they were rebuilt.These carbs have 3 types of operation. Low speed, mid range, then high speed, at which time your using a combination of the low and high speed jetting. The last and less likely, is your rotary valve and clearance. If it’s wore just a bit, can cause several things from running hot, to backfiring.

I think your cooling system is fine. If you do all you can, especially checking the sync and jets, and still have this problem, I’d focus on the rotary valve clearance.

BTW, I do t run the airbox. It’s just in my way when I need to tune. It’s designed that if you roll the ski, water won’t get in the motor, but, only if you roll it the right way to get it back up. Keep the flame arrester, ditch the box.

 

[M24per]

Sorry for not updating the thread earlier, been very busy as of late, work, newborn baby and all that good stuff so again apologies.

I added the new jet and all my problems went away, the ski is running very well and actually faster than before haha. Thanks again for all your replies, helped out a bunch!