FX-1 Fx-1 compression question.

[Spheeler]

I picked up my first ski yesterday, a yamaha fx-1. The guy I got it from didnt seem to know much of what was done to it though.
From what I can gather its got the stock engine an ocean pro vortex arrestor, riva pipe and a greater girdled/non girdled head. If you could tell me how to figure out I would be very grateful.
So I was just wondering if anyone had a similar set up and knew what the compression should be like.
Currently I'm getting about 140 in each.

Also anyone have tips on cleaning the ocean pro, mines pretty filthy!

 

[subhard]

Looks like you have a aftermarket head and exhaust. Those compression numbers are fine

 

[burton148]

Looks like a greater head and a riva red pipe. Those compression numbers are good for a stock head. I'm not sure if greater has interchangeable domes to boost the compression up a little.

 

[Spheeler]

Looks like a greater head and a riva red pipe. Those compression numbers are good for a stock head. I'm not sure if greater has interchangeable domes to boost the compression up a little.

Thanks for the info, so the compression numbers I'm getting seem alright for the set up as subhard said?
And are you able to tell how the engines running by the spark plugs or are they still too new?

 

[550headache]

i have a stock head and get 150 psi. you guys dont think with aftermarket head he should have more compression than 140?

nice ski! how much did you grab it for? have you ever been on a fx1? if not your in for a treat!

 

[subhard]

I guess it depends on elevation. How high are you

 

[Spheeler]

i have a stock head and get 150 psi. you guys dont think with aftermarket head he should have more compression than 140?

nice ski! how much did you grab it for? have you ever been on a fx1? if not your in for a treat!

I got it for 800$ the ski starts up good, has a primer kit installed. The engine doesn't sound bad in my opinion, the only problem is it seems to leak water into one cylinder. The guy I bought it from told me he thought it was the base gasket, wfo speedracer told me I couldn't be though. I'm inclined to believe its the exhaust gasket personally.
So if I got a complete gasket kit and replaced the piston rings, would that help out my compression?

Haha no I've never even been on a stand up before, just sea-doo's. I'm pretty light though (150) and I have great balance, so I'm sure I'll figure it out eventually.

 

[Spheeler]

I guess it depends on elevation. How high are you

I live in Calgary Canada, google told me the elevation is 1,084 meters (3556.43) feet.
Would higher elevations increase compression numbers?

 

[Joker]

No. The higher the altitude the less compression you have.

 

[Offroadie]

greater girdled/non girdled head. If you could tell me how to figure out I would be very grateful.
So I was just wondering if anyone had a similar set up and knew what the compression should be like.
Currently I'm getting about 140 in each.

It's a girdled head. Hard to know what your compression "should be" without knowing some other details (one of which is dome size)

 

[Spheeler]

It's a girdled head. Hard to know what your compression "should be" without knowing some other details (one of which is dome size)

Thanks! I've been scouring the internet trying to figure that out. I was planning on doing a leakdown test this weekend but after I'll take the head off and have a look. Do I just measure the width in cm to figure out the size?
And what else would you need to know?

 

[Offroadie]

There are many factors that could effect your compression... for instance a stroked crank will make more PSI than a stock crank. The domes should be stamped on the top side (only visible when removed).

 

[badvinny]

A bad base gasket wont leak water into a cylinder (unless your hull is full of water), and what the heck is a 'piston gasket'?

I got it for 800$ the ski starts up good, has a primer kit installed. The engine doesn't sound bad in my opinion, the only problem is it seems to leak water into one cylinder. The guy I bought it from told me he thought it was the base gasket, wfo speedracer told me I couldn't be though. I'm inclined to believe its the exhaust gasket personally.
So if I got a complete gasket kit and replaced the piston gaskets, would that help out my compression?

Haha no I've never even been on a stand up before, just sea-doo's. I'm pretty light though (150) and I have great balance, so I'm sure I'll figure it out eventually.

 

[Spheeler]

A bad base gasket wont leak water into a cylinder (unless your hull is full of water), and what the heck is a 'piston gasket'?

Sorry I was meaning piston rings. That's what wfo speedracer told me too. so I told him when I went to pick it up and he said it was only the cylinder closest to the tray that was getting water in it.
While he was riding it the last time it went down to one cylinder, he was trying to figure out why at home but when he hooked up the hose to the attachment that cylinder filled with water.

 

[95fx]

Any history on that FX? Since these are pretty rare i believe it was the one i saw for sale here just before summer in ontario. It had the same pipe, head, flame arrestor and stickers as the one here, and i havent seen many riva pipes on FX-1's lol

 

[Asmbandits]

If he filled one of the cylinders with water he was doing something wrong as he must have had it hooked up to the hose and not had it running, this is a big no no.. ALWAYS have the ski running with water on, turn water off then ski off.. the whole engine will fill with water if your not doing this properly. As far as water getting into the rear cylinder, its most likely a head gasket/o ring issue.. 9 times out of ten it is this, would not be piston rings or base gasket, not possible.. It could be your exhaust gasket but not as likely as head gasket (with this head id assume it uses o rings). Pulling the head is very simple, take only a few minutes.

Also odds are that your compression is a tad on the low side but not bad. Like said above you need to get the dome size to be sure but usually when you go to a aftermarket head you bump up the psi.. stock is 150 I believe.. Elevation is going to cause it to be lower than it should be but id run it how it is or rebuild it this winter.

 

[Spheeler]

Any history on that FX? Since these are pretty rare i believe it was the one i saw for sale here just before summer in ontario. It had the same pipe, head, flame arrestor and stickers as the one here, and i havent seen many riva pipes on FX-1's lol

Yea the seller told me he was working in Ontario over the summer and picked it and a js 550 up. I guess he didn't like the yamaha though because he's keeping the 550.

Do you happen to remember any particulars of the Ad, price or any issues?

 

[Spheeler]

If he filled one of the cylinders with water he was doing something wrong as he must have had it hooked up to the hose and not had it running, this is a big no no.. ALWAYS have the ski running with water on, turn water off then ski off.. the whole engine will fill with water if your not doing this properly. As far as water getting into the rear cylinder, its most likely a head gasket/o ring issue.. 9 times out of ten it is this, would not be piston rings or base gasket, not possible.. It could be your exhaust gasket but not as likely as head gasket (with this head id assume it uses o rings). Pulling the head is very simple, take only a few minutes.
Also odds are that your compression is a tad on the low side but not bad. Like said above you need to get the dome size to be sure but usually when you go to a aftermarket head you bump up the psi.. stock is 150 I believe.. Elevation is going to cause it to be lower than it should be but id run it how it is or rebuild it this winter.

Thanks for all the Info, I totally forgot about this thread or I would have gotten back to you sooner.
When he told me that I thought the exact same thing, I haven't hooked it up to the hose personally yet though.
I Figured it needed new gaskets either way so I took the pipe and the exhaust manifold off. The pipe is huge so I wasnt able to get just the head off, But I did finally manage to get a look at the domes. There are no markings at all sadly, there's some pretty bad pitting and a couple huge gashes in one.
I'm going to get a gasket kit from jetmaniac but I'm just wondering if his Ada oring set with work on my greater head.
Here's some pictures of the domes with the head taken off.
Any info you can give would be much appreciated!

And I Am planning a semi rebuild this winter, just not sure how far my budget will take me at this point haha.
Very nice looking fx-1 by the way, like the use of the original graphic.

 

[95fx]

Yea, I saw the ad, it was up on kijiji, I remember this machine because i was going to buy it, I called the guy up a couple days after it was posted and it was already sold lol I remember it was posted for a pretty good price. And about your Greater Head, Im not too sure but i havent seen many of them around, I also have a greater performance head but but am unsure of if it is girdled or not, mine does not have the 4 large outer bolts that bolt the cylinders to the cases.

Also, Those gouges on the one dome look pretty bad, Must of been chunks of the current or previous piston, Are the walls scored at all? How does that piston look? Looks like there may be chunks of metal melted to it in the picture but i cant really see.

 

[Spheeler]

Yea, I saw the ad, it was up on kijiji, I remember this machine because i was going to buy it, I called the guy up a couple days after it was posted and it was already sold lol I remember it was posted for a pretty good price. And about your Greater Head, Im not too sure but i havent seen many of them around, I also have a greater performance head but but am unsure of if it is girdled or not, mine does not have the 4 large outer bolts that bolt the cylinders to the cases.

Also, Those gouges on the one dome look pretty bad, Must of been chunks of the current or previous piston, Are the walls scored at all? How does that piston look? Looks like there may be chunks of metal melted to it in the picture but i cant really see.

Thanks for the info, I hoped he got it off kijiji. It's relieving to hear that, I've sorta been thinking it might have been stolen.
The licences haven't been updated since '98, ones from Quebec '94 and the other ontario.

I was confused about that too, but I believe the long bolts into the crankcase are what makes it girdled. I had a pretty hard time finding info about greater heads also, I found a thread on pwc today that suggests the old ones aren't very good but thats about it.
As far as I can tell the 4/6 bolts are available, so I don't see why you couldn't do that yourself if you wanted the extra security.
Is yours the same shape as mine or rectangular?

Heres some pics of the pistons and sleeves, I think i'll be needing new pistons. Ones scored pretty bad, but no visible damage other then that sadly. The sleeves look pretty good as well as the ports. So what caused that damage is still unknown.
Would something be able to do that kind of damage without doing it anywhere else in the combustion chamber. Or have the pistons been replaced since the damage was caused?