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99 GTX RFI engine nightmare

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adamsbj123

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I had my 787 RFI engine rebuilt by SES. I finally received it back after 7 months. I installed it and had to wait 3 months to finally test it. After running for about 5 minutes I found water was entering 1 of the cylinders. I pulled the engine and sent it back. They found 1 cylinder had a small crack. I just received the engine this week and installed it again. I tested it at home and it seemed to run fine. I took it to the lake today and it would barely start in the water. I finally got it started and it ran like crap. If I got above 20 MPH it would take off fine. Anything below 20 MPH and it would run very bad and finally die and not restart. I pulled the plugs and found them badly fouled ,The mag cylinder plug is wet the other plug has heavy soot. I installed fresh plugs and still the same problem. I now don't see any sign of water entering the cylinders. I have double checked everything I can think of. Compression in both cylinders is 150PSI, The fuel injectors are both new, The raves are new and clean, The battery is new, The marks on the oil injector pump are lined up correctly,The gas is fresh, I have no warning beeps or messages on the display.
Any thoughts or help is greatly appreciated.

Thanks.
 
have ever trimmed off like a 1/4 - 1/2 inch off the sparkplug end of sparkplug wires ?????
you have to sorta loosen up end of sparkplug boot with like a pocket screwdriver, and screw off boot, trim off cable with utility knife and see if inner wire is all rusty and corroded looking .....

also, maybe swap injectors and see if pto cylinder plug fouls

and you know im sure, that if its not charging, it will run like crap

these skis go through rectifiers
 
Yes, I did trim the spark plug wires also.
I will start it and check to see if it is charging. Although the battery is new and I don't have a "low Voltage" warning.
I don't understand why it is now very hard to start in the water. This ski used to start almost instantly with my original motor.
 
Check rv valve timing, it being off can make things run crappy on the low end. Check injectors as griz said.
 
griz400 said:
.010 - .016 on the clearance, and it should be at 147 degrees
Click to expand...

The rotary valve was all set by SES during the rebuild. Both injectors are new from 5-O.
You might be on to something with the voltage/rectifier. I just checked the battery 12.7 volts at rest. I started the ski and gave it a couple of quick revs. The voltage climbed to 13.2 volts. This seems very low to me. What should the voltage be when I start it out of the water and rev it?
 
13.5 is good, yours is ok at 13.2, 13.5 at 3000 rpms, you probably have a rotary valve clearance issue, im just guessing, when the rotary valve turns, and covers up the intake passages, if clearance is too high, one cylinder robs the other (the best way i can explain it) , did he put the rotary valve and the rotary valve cover on the engine ??? most leave that up to the owner, also, the tps and apps sensors can be plugged in backwards, one will plug into the other, i would check rotary valve clearance now, that is charging,and maybe swap injectors around .. this issue is usually resolved by compression -- or -- rotary valve clearance
 
SES custom cuts the rotary valves for each engine to get close to spec as possible. On my last 2 engines from fhem I just left the valve as is and hzd no problems. I doubt it is a rotary valve timing issue.
 
you cut the cover, or replace the cover if it is too screwed up, you can measure it with a bent feeler guage by pulling t/body assembly, or pull cover off, and install some solder and re-install cover, pull it off and mic the solder.... did you check your clearance ???? did you install your cover ???
 
griz400 said:
you cut the cover, or replace the cover if it is too screwed up, you can measure it with a bent feeler guage by pulling t/body assembly, or pull cover off, and install some solder and re-install cover, pull it off and mic the solder.... did you check your clearance ???? did you install your cover ???
Click to expand...
SES installed the new rotary valve. It was in place when I received the engine. I installed the cover. I was not aware of needing to measure gaps etc. It was my understanding that he cut a new valve to match the old one. Are you saying the rotary valve clearance may be my whole problem? Causing hard start, poor running and fouled plugs?
 
i would check it ..... as far as a custom install like rob said, it wasnt done, and he obviously didnt pressure test the first motor he sent you or it wouldnt have leaked water into cylinder, --- i feel bad for ya man, but some things need checked, -- check them connectors i was referring to also -- you should have a 159 degree rotary valve in the engine, set at 147 degrees

and here, this will sum up what i was saying about rotary valves

A rotary valve refers to the intake of earlier Sea-Doo two stroke engines. The rotary valve are driven off of a gear in the crankcase between the cylinders. This motion allows the intake port to be opened and closed in time with the engine power pulses. The rotary valve allows the port to have no restriction. Rotary valve engines are a very effiecient design with complete control of airflow into an engine. They allow the air/fuel mixture to flow without any airflow restrictions (unlike like reeds).
except on an rfi, its air and oil, fuel is on other side of motor

View attachment 21449



here is a pdf file of a degree wheel, print it out, cut it out, and check yours
 
Last edited by a moderator:
griz400 said:
i would check it ..... as far as a custom install like rob said, it wasnt done, and he obviously didnt pressure test the first motor he sent you or it wouldnt have leaked water into cylinder, --- i feel bad for ya man, but some things need checked, -- check them connectors i was referring to also -- you should have a 159 degree rotary valve in the engine, set at 147 degrees

and here, this will sum up what i was saying about rotary valves

A rotary valve refers to the intake of earlier Sea-Doo two stroke engines. The rotary valve are driven off of a gear in the crankcase between the cylinders. This motion allows the intake port to be opened and closed in time with the engine power pulses. The rotary valve allows the port to have no restriction. Rotary valve engines are a very effiecient design with complete control of airflow into an engine. They allow the air/fuel mixture to flow without any airflow restrictions (unlike like reeds).
except on an rfi, its air and oil, fuel is on other side of motor

View attachment 21449



here is a pdf file of a degree wheel, print it out, cut it out, and check yours
Click to expand...

OK Thanks.
I will check the RV timing and gap tomorrow.
As far as the 2 plugs. I have the plug with the 3 solid colored wires black, white and purple to the throttle position sensor. The other connector has 3 striped wires.
 
I took it apart to inspect and found the Rotary Valve timing off by about 35 degrees. This was set by SES during the rebuild. The cover clearance is within spec. I will go to the lake and test it again tomorrow.
 
Wow, if true this makes me wonder if the balance shaft is installed properly. Just be glad the crank pins are 180* out from each other, or are they? Can't assume anything I guess, might want to check on that one too.
 
good you found it out and fixed it, you will like the rfi package, after you break it in, set idle at around 2500 on the trailer, it will be about right in the water, i keep my idle lower in the water, and control it all with thumb, thats me though, i found out the lower the tps, the more it is responsive, keep some synthetic seadoo oil init, also fresh gas with no additives, and no extra oil, you dont need any of that crap screwing up your new injectors, etc, etc

let me know how it runs
 
Just got back from the lake. It runs great. I am going to buy the Seadoo R/V guage and reset the timing again. I have it real close using the paper cutout. But I still have a very slight cutout-hesitation at the low end. Probably just a little off on the timing still. But the ski runs very well now that the timing is set.
Many thanks to Griz and the rest of you for the help. You are great!
I now have a much better understanding of the R/V and the timing. I will never trust a rebuild shop again. I just want to mention one other important issue I found with SES. When they shipped my engine back the first time the counterbalance oil was empty. When they shipped the engine back the second time the counterbalance was again empty. They did not include a note to fill it or anything. I just happened to check it before installing. So to all of you guys who sent 787 or 951 engines to SES you better check your counterbalance oil!
 
Im happy that you have it up and running..

The one good thing that comes with issues is,,, by the time you get it right you have fixed/updated other things that probably needed done anyways...
 
Glad to hear that it is now running great. I would have never thought that they got the rotary valve timing wrong. I would mention this to Tom cuz I am sure you wasted a fair bit of time needlessly troubleshooting. Now go out an enjoy it while the weather is still good.
 
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