1991 bombardier xp compression?

[troypusich]

It starts and runs okay sitting on the trailer, once i get it into the water it takes a little to get it running, once running..... It seems as though it will only run/use the fuel that is in the line then it dies, well tried to die (not run) till I choke it/prime it up a few times then the process starts over. i have been told to check the compression, but im not sure what to be expecting. i have ready online somewhere around 130 would be good? is this correct for this engine?

 

[Dr Honda]

150 psi is what your engine should be. BUT... it sounds like you have a fuel issues. Running on the trailer doesn't count since there isn't a load on the engine.

 

[troypusich]

150 psi is what your engine should be. BUT... it sounds like you have a fuel issues. Running on the trailer doesn't count since there isn't a load on the engine.

So if it won't start in the water, how do I test the compression? I was getting about 130 on dry land

 

[LouDoo]

It won't make any difference if you test compression on the trailer or on the water. In fact it will be a lot easier to test on the trailer.

Test the compression with a cool or cold motor, remove both spark plugs, ground the spark plug boots on the grounding lugs. Open the throttle full, and crank the engine over until the gauge peaks. 130psi is not real good but it's not terrible, you should be able to use it through the season.

Where in the United States do you live, it's a pretty big place?

Lou

 

[troypusich]

It won't make any difference if you test compression on the trailer or on the water. In fact it will be a lot easier to test on the trailer.

Test the compression with a cool or cold motor, remove both spark plugs, ground the spark plug boots on the grounding lugs. Open the throttle full, and crank the engine over until the gauge peaks. 130psi is not real good but it's not terrible, you should be able to use it through the season.

Where in the United States do you live, it's a pretty big place?

Lou

I live in northern california. My best guess as to a plan of action is to redo the hosing and new reserve switch and primer. For some reason every time I get it on the water it suddenly won't prime either. I'm thinking maybe the bouncing around in the truck on the way down keeps knocking hoses loose

 

[LouDoo]

I lived in Northern California right after I graduated from college. Loved it, I lived in a little place called Sunnyvale, probably not so small today.

We really need to get an accurate compression reading to get a general idea of the condition of the engine.

Lou

 

[Spimothy Leary]

I live in northern california. My best guess as to a plan of action is to redo the hosing and new reserve switch and primer. For some reason every time I get it on the water it suddenly won't prime either. I'm thinking maybe the bouncing around in the truck on the way down keeps knocking hoses loose

hose's generally won't bounce loose or off while riding on the trailer assuming they are not dangling in the first place., i think you can eliminate that from the probable causes.

 

[S_eadoo]

It won't make any difference if you test compression on the trailer or on the water. In fact it will be a lot easier to test on the trailer.

Test the compression with a cool or cold motor, remove both spark plugs, ground the spark plug boots on the grounding lugs. Open the throttle full, and crank the engine over until the gauge peaks. 130psi is not real good but it's not terrible, you should be able to use it through the season.

Where in the United States do you live, it's a pretty big place?

Lou

When I tested mine I only removed one spark plug at a time. I did not open the throttle. I just turned it over to get the max reading. Will this give me a false reading? I ended up with a very high reading on the front cylinder and low on the back one. If I remember correctly it was about 180 on the front and 140 on the back. I have the 787 motor in my GTX.

 

[LouDoo]

The reason for opening the throttle is the motor will get a full gulp of air. The reason to remove both spark plugs is the starter won't have to fight against compression, the motor will turn over faster and you'll get a more accurate reading.

The 140 is O.K. but the 180 is way high, ideally the compression should be around 150 on both cylinders. I would recheck the compression if there's still that big of a difference you need to start a thread.

Lou

 

[68ragtop]

Keep in mind that all compression gauges are not always equal. Cheap ones are available everywhere. But are not always accurate. A good tester will have an assortment of different fittings that will match the depth of the plug you are removing so there is no added chamber volume, & the pressure valve is in the very bottom edge of that fitting. Also don't be alarmed that it takes several compression cycles to get up to the max reading. This is the process of the gauges hose getting up to the same pressure that the cylinder is capable of. When it stops moving, that’s your pressure. The longer the hose on the tester, the more cycles it takes. Some of the cheaper testers have a bunch of threaded adapters to Fit different plug holes. These adaptors effectively add volume to the chamber, lowering your compression & those cheap gauges just aren't accurate anyway.
The biggest thing IMO is have the pressures being equal with what ever gauge you have. IF both are right at 130 +/- 2-3lbs It might be the gauge. If ones is more than 5-10lbs different than the other side you probably have an internal problem.

 

[Vandyck]

Hi,

Just a question, when i open the throttle, the gas will be pull inside the cylinder?

Thank you

 

[troypusich]

okay so i am looking at 130 on cylinder 1 and 128ish on cylinder 2. i have good compression so what could be causing this? im lost!

 

[LouDoo]

Actually you don't have good compression, but you do have enough compression that the ski should run in the water. So we need to start looking for fuel issues. I'm not that familiar with older ski's, does your ski have grey tempo fuel lines?

Lou

 

[troypusich]

well yeah, i meant good enough to eliminate that as a problem. the fuel lines are all grey. I recently bypassed a lot of stuff. I have a fuel line running directly from the fuel tank to the carbs. I have been hand priming it and figure when i get it running on the water ill just keep an eye on my fuel level and i always ride with someone else anyways. so i dont see where i could have an issue with fuel lines.

just to be clear, when i run the jet ski on dry land with the garden hose running in line, is that EXACTLY the same as running it in the water???

 

[LouDoo]

So if it won't start in the water, how do I test the compression? I was getting about 130 on dry land

O.K., so you were incorrect in post three when you said it wouldn't start when in the water, we're already on post 15 and I still don't know what the problem is, I thought it wouldn't start when in the water. When it starts in the water exactly what is it doing? Does it bog down or does it rev up but doesn't go anywhere?

Lou

 

[troypusich]

okay, originally it was just cranking and wouldnt ever actually start. i was getting spark and gave you the compression readings. at this point, i have had it running in the water once, took it for a quick loop and then it died. i think im gonna rebuild the carbs, any good websites selling cheaper rebuild kits??

 

[68ragtop]

So is it currently on your trailer, & not starting? I can't see too much that would change in the water other than the angle of how it sits & the load on the engine when it does run.

If it seems to be fuel related, I would check something in the tank in addition to the fuel filter. Before tearing into the carbs. On both my 92 seadoo's the fuel pickup hoses deteriorated to the point of crumbling. There are two hoses inside the tank, they are shrouded by a plastic tube that extends to the bottom of the tank. One line is hooked to your reserve connection & goes to the bottom of the tank. The other is several inches shorter & connects to the main line. Pop that out & take a peak, just a 5/16 nutdriver & you can check them in a few minutes.

 

[troypusich]

Well it will start on the trailer. Those hoses were deteriorated when I bought it but I replaced them already.