96 Xp 787 hard to start then bogs. POP the choke and it pick up and go fast.

[Chris488994]

Hello I have a 1996 Xp with the 787 Dual carb RAVE engine. I bought it used and was sitting for 2 years before. I did alot of work to it listed below, but this is the problems I had after all my work and finally got it out to a lake.

It is hard to start when cold and then bogs and dies when you give it gas. Will start back up and idle then bogs on throttle up. If I (POP) pull the choke give gas and let go of the choke it will take off and run great. Lots of power good top speed and a blast to ride. As long as I keep the RPM's up it will run fine. If I let it go back to idle then ill have to POP the choke again and it takes off. Ran like that most the day then it didnt work anymore. Started to bog all the time. Sounded like the motor was trying to go but would just shake alot and knock. After a 20 minute ride back to the dock at a high idle, I got it back on the trailer. Reved up fine but wouldnt hit top end. I have read and read for hours online the manual and I dont know where to start.

Any help would be greatly appreciated.

Here is what I did to the ski before I even took it out for the first time. Everything by the book.

Before I even bought it I Checked the compression and Spark. Compression was 155 on both cylinders. Nice strong blue spark.

Drained the fuel tank. Put in some fresh gas and it started. Seemed to run pretty good on the trailer. Reved up and idled at 3000 RPM.

I did not want to take the chance of running it LEAN so I pulled both carbs and went through them. The carb filters had a little bit of dirt but not bad. The big round diaphragms were still flexable and the ones on the other side were as well.

Checked the pop-off and both needles popped around 43 PSI. My book says 38 +/- 10. Thats if I have the black springs but im not really sure what color they are. Definatlly a darker color. Pressure leak test held for over a minute at 10 and 20 PSI. Did the suck and blow test on the inlet and outlet and they showed a resistance but would not hold a vacuum. Book doesnt say. I dont know.

Changed all the gray lines on the carbs only and put a clear inline fuel filter. When I cranked on the starter the filter filled up pretty fast. With a good flow. Started it on the trailer and it ran pretty good.

Got it in the water and it runs like crap. Was hard to start when cold then bogs down when you give it throttle. If I POP the choke it will take off and haul but.

Please help me.

 

[Dr Honda]

An 800 XP's pop-off should be 26-38 psi. (I think you were looking at the spec for the 717 engine) So, at 42... it's too high. I would take the carbs apart, and verify that they are clean, and set the pop-off to around 32 psi.


Now... as far as it runs poorly, and is knocking...

There is a good chance that you have burnt the engine from running it excessively lean. With a 2-stroke engine... if you have a fuel problem... stop running it !!

When you pop the choke... you are forcing the needle to open, and you will get higher vacuum at higher RPM's to hold it open. But, you loose all the fuel that would normally take you though the mid RPM range. In turn... your mix is lean.

First thing to do is to check the compression. (after taking care of the carbs)

 

[Chris488994]

Thank you Dr Honda, Thank you so much for replying. That all makes sence. I have a couple videos below you can watch. My manual doesnt specify which engine just the different springs and valve seat size. My valve size is 1.5 and im not quite sure what color my spring is. I think its what they call black so it would be 80 g spring load. I dont know if its a dull silver spring that has turned black or what. I have the needle lever set flush.

Does it have to be flush?

What color spring do I need?

As for the running lean condition, I know excatly what you are talking about. Thats the reason I went through the carbs in the first place because I spent hours doing my homework and researching every thing before I even ran them.

I repair and sell lawn equipment to get me through college and I get alot of chainsaws and weedeaters with siezed pistions. I always run them with as much oil and as rich as possible without fouling plugs. High performance is second to engine life.

Speaking of, my new plugs were black so I know it was getting fuel.

Today after the lake the first thing I did was check the compression again. Both cylinders were right at 150 WOT. So I sand blasted the plugs, checked the gap (22) and ran it. Same thing. It will start up and will run like crap on higher RPMs. Wont spool up all the way. Poping the choke doesnt work anymore.

Pulled the plugs and they are a little black. Checked the spark and both have a steady strong blue spark, you can even hear it.

I set the low speed needles at 1 and the highs at 0.

Here is the video at full throttle.

 

[Dr Honda]

Thank you Dr Honda, Thank you so much for replying. That all makes sence. I have a couple videos below you can watch. My manual doesnt specify which engine just the different springs and valve seat size. My valve size is 1.5 and im not quite sure what color my spring is. I think its what they call black so it would be 80 g spring load. I dont know if its a dull silver spring that has turned black or what. I have the needle lever set flush.

Does it have to be flush?

What color spring do I need?

No... the arm doesn't need to be flat. But you start with it level, and give it a bend to fine tune the pressure. I think the max deviation is +-1mm. If its more, or less than that... you can have problems.

For 32 psi... and a 1.5 N/S, I would use a shiny silver spring. But... you always have to check the pop-off. I've put new N/S, with the proper spring... and I get crazy pressures. You have to check it, and change the spring if needed.

With what you have described... your pop-off is just way too high, and you can't get it to flow fuel when the vacuum falls off. (that's why you have to pop the choke) OR... the pilot/bypass circuit is plugged up.

Speaking of, my new plugs were black so I know it was getting fuel.

Today after the lake the first thing I did was check the compression again. Both cylinders were right at 150 WOT. So I sand blasted the plugs, checked the gap (22) and ran it. Same thing. It will start up and will run like crap on higher RPMs. Wont spool up all the way. Poping the choke doesnt work anymore.

Pulled the plugs and they are a little black. Checked the spark and both have a steady strong blue spark, you can even hear it.

I set the low speed needles at 1 and the highs at 0.

I'm glad you have full compression still.

As far as the "Plugs are black" thing... we know it was getting fuel because it was running... but they would be black because every time you pulled the choke, it went rich, and since it wasn't running right... you never ran it long enough to get them to burn clean without popping the choke again.


Finally... please don't double post. I'm going to have your second post with the same info deleted. It just confuses things.

 

[evanssd1]

did you ever get this resolved?

 

[Chris488994]

No I haven't fixed it yet but I think it was the bad rectifier messing with me. My new one is in the mail.

I will let you know if it fixes my problem.

 

[evanssd1]

cool, i was having the same problems. got an expert mechanic to rebuild the carbs. still had the problem. he threw them away and replaced them completely. ski runs like a top now (just ran it today for the first time).

95 XP Limited 800

 

[evanssd1]

and now my original problem is back, any luck fixing yours?

i get the weird bog out and random times while riding at any random speed. i have to turn the ski off and back on again with wide open throttle then it starts running good again. Then it will randomly bog out again. Arghhhhhhh.

 

[Chris488994]

No sorry bud I haven't got mine on the water yet. Planning on Saturday, the only thing I did was change my rectifier. Because I already went throughout my complete fuel system even new lines.

I didn't know the 95's had the 800 in them. Have you checked your voltage to the battery.

You need to check voltage before you start it, while it's at idle and at 5500 rpm. Make sure you hook up the water and never have the water on unless the engine is running. You can't run it too long or else you will heat up the carbon ring. I've read 5 minutes at the most.

It shouldn't take to long to check the voltage. It should be 13.5 - 14.5 anything over 15 volts is no good and the rectifier will need to be replaced.

Mine was reading 16.5 volts and jumping all over the place. On my ski the CDI is ran off of the batt. DC. Alot of other skis are AC-CDI so the rectifier doesn't affect the spark.

Good luck and let me know what you find out.

 

[evanssd1]

cool, many thanks for the tips, i am very much still a noob to jet skiis. i have a 95 XP Limited 800, it was the first SeaDoo w/ the 787. I will post up my results!

 

[evanssd1]

check the voltage at the batter with the ski on a trailer. started in the low 13s and went up in the 13.6 range when revving the engine. Unfortunately I don't have a tachometer so I have no idea what my RPMs are.... back to square one a I guess. I have no idea what is wrong w/ my ski.

PS. I wasn't able to reproduce the bog/engine stall issue while testing either.

 

[DrMarc]

check the voltage at the batter with the ski on a trailer. started in the low 13s and went up in the 13.6 range when revving the engine. Unfortunately I don't have a tachometer so I have no idea what my RPMs are.... back to square one a I guess. I have no idea what is wrong w/ my ski.

PS. I wasn't able to reproduce the bog/engine stall issue while testing either.

I'd been having the same bogging issue with my 96 xp, it would run fine on the trailer but drop it in the lake andit would chug around for like 5 minutes barely about to go over 5mph while spouting out smoke then all of a sudden it would go, and run fine, but occasionally bog down again.

But then i read about someone else having the same problem and it turned out to be the ignition coil. And voila, new coil, no more bogging

 

[crashxp800]

considering this post isnt too too old.. i was having the exact same issue.. changed starter relay and ignition. what finally helped was replacing wires and using dielectric grease on all connections.. there seemed to be a bad connection on inside cover of rectifier.. hope you got your up and running.
95 xp800

 

[Dr Honda]

considering this post isnt too too old.. i was having the exact same issue.. changed starter relay and ignition. what finally helped was replacing wires and using dielectric grease on all connections.. there seemed to be a bad connection on inside cover of rectifier.. ran good until...

friend hit a sand bank/log
Now.. the ski runs good cold. but when it warms up it is rough and wont start / run...?? any ideas..

edit.. compression is 135 pto cyl. and 140 front.
95 xp800

It is old... and it's a "No-No" to ask questions on someone else's thread. You should start your own thread.

Your problem isn't the same. It sounds like you have an overheating issue.

Start a new thread, and we will get you fixed up. :cheers:

 

[evanssd1]

just an fyi - even though my voltage regulator tested out fine with a meter a couple of times it finally showed up as bad. replaced the voltage regulator and the ski has been running perfectly all summer long.

 

[Chris488994]

I know this post is old but a lot of people read these for reference so I thought I would do a follow up on everyone.

Dr. Honda, thank you again for all your help. I found out my psi gauge I was using for the pop off test was reading 10 or 11 pounds too high. So they were set pretty close to 32 psi.

Evanssd1 just wondering if you still have your Seadoo XP and if you took it out this season? How did it run? Did the rectifier fix the problem for good? Well bud I hope all is well.

DrMarc how is you ski treating you if you still have it. Did the new coil fix it for good?

Crashxp800 same for you did tightening up the connections and adding the dielectric grease fix everything?

Unfortunately I wasn't able to take my skis out this season due to gas prices (CA) and finances. So I haven't even put in my new rectifier yet.

Hope to hear from you guys.