94 XP won't start

[stumpy]

I have a 94 XP with SBT motor and about 15 hours on it. It acts like it ran out of gas, but it has gas in it. I replaced the spark plugs and it will start for a second and then stop. Inside the hull was clean and dry, so it did not ingest water....at least in the carbs. Could an internal gasket or seal have failed?
I use premix gas at 40:1. The top of the pistons are dark colored. The old spark plugs were kind of brown. The motor ran great up until this point.
I checked the compression and the mag cylinder is at 140 while the pto cylinder is at 150. I don't know what they should be at, but this seems high enough, just not close enough together. My 94 GTX with old motor is at 155 in both.
Is this some sort of seize? If not, then where do I go from here?
Please help.... :(

BTW, I had the carbs rebuilt by shop at time of motor replacement.

[Bryan Glynn]

It could be damaged, but we need some more info to know...try turngin it over with the plugs out and see if excessive oil comes out. Double check that the rotary valve is still timed correctly, and the brass gear hasn't slipped. Does it ever backfire? Do you see gas being blown back out the carbs if you crank it with the flame arrestor off? Did it die while you were riding it?

[stumpy]

Bryan,
It did die while I was riding it. I turned it over with the flame arrestor off and plugs out and it did not blow excessive oil out the plugs holes nor did it blow anything out the carb. It has never backfired. One thing I did notice, though...when I was turning the engine by hand with the pto, in order to see the top of the pistons, I heard a squeaking noise. Kind of like something rubbing on rubber. I Don't know what that is. I will look at the RV after I get the carbs off.
Any ideas with this info?
Stumped, I mean Stumpy :D just trying to keep a good mind about myself.

[stumpy]

New update.....I noticed a new sound while turning the pto by hand. A clunk........sounds like something a miss in the bottom end. Holding the pto, I turn in back and forth ever so slight and can hear a clunk from the bottom end. At first I thought it was in the drive shaft, but after further evaluation, it is not, it is from the bottom end. Sounds to me like something is very wrong.

[Bryan Glynn]

DO like I said and check the valve.

[Bill O'Neal]

All rotary valve Rotax motors make a slight clunking noise when the pto is turn forward and back, so don't panic unless it is very loud or a grinding sound. The clunk is the gear lash of the RV shaft and Crank gears.

Starts, runs a couple seconds then dies, is it possible that you reversed the fuel lines when installing the carb ? "on" line to bottom fitting, "return" line to upper fitting is the correct way to connect the hoses.

[John Kubiak]

I agree with Bill, check the fuel lines first!!

[stumpy]

The ski has 15 hrs plus of flawless riding since break in. Could it do this with the fuel lines switched? I will still check, though....I am still in the process of checking the RV and shaft.

[Bill O'Neal]

No, your lines cannot be reversed if you ran it that long.

But I still think you have fuel delivery problems.... Or you have siezed it. Check your compression.

[stumpy]

Well, my job has taken me away for the past few weeks. Anyway, I removed the RV cover and the RV is aligned the same way it was upon installation. The past few weeks have brought on more symptons, however. When I tried to move the PTO to put the MAG cyl at the top to check the RV timing, the engine was extremely hard to turn. I also noticed surface rust on the RV itself. BTW, the RV was new upon engine replacement. Probably just time for the RV, but the crankshaft seemed like something was wrong, like the bearings were seized or something.
My work schedule is very hectic for the next few months. If this is a warranty job, will the time lapse between taking the motor out and sending it be a big deal. I just want this thing fixed, warranty or not. I can't think of anything I did to seize it up, but obliviously they don't just do it all by themselves. Any ideas to keep this from happening in the future would help. I know I am jumping a little ahead, so that's it.
Please help :(

[stumpy]

I checked the RV like you said, Bryan, and it was OK. Where do I go from here?

[Bryan Glynn]

Well, let's get it swapped out, but we still need to figure out what went wrong. With rust ont he RV, you definitely have excessive water or moisture int he case. What did you treat the exhaust manifold gaskets with?

Call in and ask for Julie, she will get you in the computer and get the block swapped.