95 XP milkshake

[Captain959]

My 95 XP was running ok, a slight miss around 4000 rpm. The other day it ran for 15 minutes and would not restart. It hit real hard when it cranked. I pulled the plugs and I fear I've got a bad head gasket or a cracked head, there's a mixture of oil,gas,and unfortuantly water. Any ideas?

[Bill O'Neal2]

Re: 95 XP milkshake

Could be any gasket, like the base gasket, exhaust gaskets or a crack in something. Your motor does not use a head gasket, it has orings. Done any work to it lately?

[Captain959]

Re: 95 XP milkshake

Well I pulled the cover off and the pto cyl had a milky brown coating while the mag cyl looked ok. The o-ring on the mag cyl wall was split, while the others looked intact. The strange part is that both plugs had the milky coating. Also both cyls have 150-155 compression. I read that you shut the water off before the engine when flushing or testing, what difference will that make? I shut the engine off first and then the water. Woops?

[bmclaws]

Re: 95 XP milkshake

I found out the hard way that you start the engine and then turn on the water and likewise turn off the water first, rev the engine few times to clear the exhaust then shut off the engine. Turns out the owners manual (which didn't come with the ski when I bought it) has several warnings in the flushing section about the proper sequence.

Turning on the water first can and likely will back fill the exhaust manifold with water and that will flow into the engine and possibly/probably the crankcase.

I ran the water two or three minutes before trying to start my Yamaha and it wouldn't crack more than a split second. Luckily, I pulled the plugs, found the water, cranked and cranked with the plugs out to clear the water.

After 10-15 minutes of intermittent cranking, all but some vapor remained. I reintstalled the plugs and started the engine, turned on the water, and flushed it for 10 minutes or so. Everything seems fine.

[Captain959]

Re: 95 XP milkshake

I replaced the champion plugs with ngk and rode it, thats when it wouldn't restart and I noticed the water in the cyls. It cranked like it was hitting hard on one cyl. I put it on the trailer and brought it home. That was Sunday. Tonight is when I tore it down.

[Bill O'Neal2]

Re: 95 XP milkshake

Both plugs get oily water on them because of the transfer through the exhaust manifold, even if the leak is in only one clyinder.

[Captain959]

Re: 95 XP milkshake

So it sounds like the leak is in the pto cyl? I don't mean to sound ignorant, but I'm trying to learn about this motor. How does water get in the cyl when it is hooked up to the flushing port? And what do I need to do to rid myself of the problem? Thanks.

[bmclaws]

Re: 95 XP milkshake

With my "newbie" understanding of the whole 2-cycle jetski engine configuration here's what I've been told/read:

Some or all of the cooling water that circulates through the engine is ultimately dumped into the exhaust line and expelled out the back of the ski along wth the exhaust flow.

Flushing the ski without the engine running can/will cause the water to back up in the exhaust line and flow backwards toward the engine.

Since some/all 2-stroke engines use a series of ports to direct fuel/air and exhaust flow through the engine (as opposed to valves), the water can flow backward through these open ports and into the crankcase filling everything with water.

It happened to me the first time I flushed my ski (failure to read instructions may have been a contributing factor :emoticonn).

Removing the plugs and cranking to remove water worked. After that, reinstalling the plugs, arting and running ski to warm up and remove any remaining trapped water/vapor restored the ski to operation.

Hope that helps...

[Captain959]

Re: 95 XP milkshake

Thanks, my understanding of these Sea-doo's is improving and I might even be able to fix one soon. Waiting for o-ring's from SBT so I can put it back together. Thanks for the info.