• This site contains eBay affiliate links for which Sea-Doo Forum may be compensated.

1995 GTX engine works on one cylinder

Status
Not open for further replies.
T

TheGunMan

New Member
Hi all,

a week ago I got used GTX. Ran it last Sunday and besides that it startad hard and angine wantet to stop if throtle released all the way for first few minutes it ran great - 45+ mph with two persons on board.

Today when we went to the lake it started not so hard but again the engine wanted to quit if the throtle was released all the way. Unlike last weekend when I pushed the trottle all the way it startet to "rev" but no power at all. After 10-20 sec like that it starts to gain speed but once thorle released it wants to quit again. If thortle pressed again it need agai 10-20 sec to start mooving fast /not as fast as last week/.

Then it was impossible to start it in the water. I start it on the trailer but once in the water the engine stops.

I did simple check - out of the water start the engine and unplug one of the spark plugs from the cable - if I disconnect the spark plug cable from the "front" cylinder nothing changes, if I dosconnect the spark plug cable from the "rear" cylinder engine wants to quit ulnes i give throtle but even then it is almost dead.

Is it possible to have bad cables/boots/spark plugs or it is something with the engine?

I realy hope that it is simple as high voltage cables and nothing to do with the engine rebuild

Thank you to everyone for the help
 
From your write up it is obvious that the one cylinder is not firing. You could start by checking the spark at the plug. If you have spark there, I would run a compression check. If you have spark and the compression is good then you can move on to the fuel supply.
 
Not to be the bearer of bad news... but I doubt it's an ignition issue. (not very common) Also, on a 720 engine... it's one coil firing both plugs. But, with that said... did you replace the spark plugs? Cleaning them doesn't normally work.

Also... If you continue to run a 2-stroke engine, when it's not running properly... you normally cook it.

So... first thing to do, is to check the compression. Get that for us, and we will go from there.
 
Dr Honda said:
Not to be the bearer of bad news... but I doubt it's an ignition issue. (not very common) Also, on a 720 engine... it's one coil firing both plugs. But, with that said... did you replace the spark plugs? Cleaning them doesn't normally work.

Also... If you continue to run a 2-stroke engine, when it's not running properly... you normally cook it.

So... first thing to do, is to check the compression. Get that for us, and we will go from there.
Click to expand...

Dr Honda, thanks for the answer even I don't like it :(

My engine is not 720 but 657 if ot makes any diference

Forgot to mention that the ski has reg sticker fro 99 which may be when it was last on water / unles there is no problem runing with old reg stickers/

I tried to get the carbs out but one bolt can not be unscrewed :(

I also discovered another problem / or two / - where the pipe connects to the engine tehre is missing / broken bolt / ant it is the front inner one. Ot si most likely broken since simple test with wire in the bolt hole shows that there is something left in there. The front outer screw is loose - there is more than 1 mm gap between the bolt head and tne lock washer and I tried to tight or remove it with no luck. May be I am not using the correct tool.

I need to take the pipe out in order to fix the brocken bolt and may be to replace the gasket.

Any help is apretiated

P.S. I will buy compression test gauge but have no idea of how to test correctly - just plug and crank or there is something else?

Thank you
 
Once you get a compression gauge. Revome the plugs and screw the appropiate gauge into the spark plug hole. Turn the engine over for several revolutions and read the gauge. Use the reset button on the gauge to return it to zero and then do the next cylinder. I do not know what the specs are for the compression reading on that particular engine, but get the readings and post them and I am sure someone will respond. As a side note some auto parts will let you borrow tools if you leave a deposit with them. My local Autozone will do that.
 
take plugs out.......screw in compression guage.....set to zero........HOLD THROTTLE WIDE OPEN....crank till needle stops moving.........post numbers back on both cylinders doing those steps......

you should see a reading between 125 --150 150 is great anything lower than 125 u will need a ring set soon
 
brock1 said:
take plugs out.......screw in compression guage.....set to zero........HOLD THROTTLE WIDE OPEN....crank till needle stops moving.........post numbers back on both cylinders doing those steps......

you should see a reading between 125 --150 150 is great anything lower than 125 u will need a ring set soon
Click to expand...

Bad news :(

It looks like I have BIG compression problem - the rear cylinder is 90 psi the front is 30

Is it only rings that to be chaned or I have to revuild the cylinders with new pistons/rings?
 
YEAH THATS VERY LOW ......not to be a dick but are you sure you did it right ???? thats a pretty wide compression range and if it were truly that low i dont think it would even be running........ AT ALL
 
brock1 said:
YEAH THATS VERY LOW ......not to be a dick but are you sure you did it right ???? thats a pretty wide compression range and if it were truly that low i dont think it would even be running........ AT ALL
Click to expand...

What I did is to screw the gauge hose to the spark plug hole, throtle wide open and crank until the pointer stops moveing

the 90 PSI cylinder is the one which worked out of water with the spark plug unluged for the other cylinder

once the ski is placed in water the engine stops if it was running or can not start if atempted to start in water
 
brock1 said:
well it sounds like you did it right but....... where did you get the guage from
Click to expand...

harbour freight

even it is cheap is it possible to have reading error 3-5 times

and I have no idea what the previous owner did with the ski

the top of the engine was never opened since the socked removed some of the white paint from the bolt heads and 3 bols can not be removed so far
 
Any idea how to remove bolts on the cylinder head cover - it looks like the loctite from the factory works very good and there are some that don't want to start
 
TheGunMan said:
Any idea how to remove bolts on the cylinder head cover - it looks like the loctite from the factory works very good and there are some that don't want to start
Click to expand...
z

First of all be sure to use the proper socket ie, a six point for maxium grip on the bolt head. Try to get as much leverage as you can ie use a short piece of pipe on the handle of your rachet or better yet use a long break over bar. You can try to heat them but use extreme caution. Be sure the unit is in a well ventilated area. If you need to try some heat I would recommend you try a hair dryer first, works sometimes, sometimes not. I have also used the small pencil torches that you can buy at Harbor Freight. Just be really careful!!!!!

Also if you have to rebuild the cylinder I recommend you try Full Bore. You can visit their website at fullboreonline.com.
 
Last edited by a moderator:
riding high said:
z

First of all be sure to use the proper socket ie, a six point for maxium grip on the bolt head. Try to get as much leverage as you can ie use a short piece of pipe on the handle of your rachet or better yet use a long break over bar. You can try to heat them but use extreme caution. Be sure the unit is in a well ventilated area. If you need to try some heat I would recommend you try a hair dryer first works sometimes, sometimes not. I have also used the small pencil torches that you can buy at Harbor Freight. Just be really careful!!!!!

Also if you have to rebuild the cylinder I recommend you try Full Bore. You can visit their website at fullboreonline.com.
Click to expand...

I was thinking to use Full Bore service if needed but first have to manage to open the engine

will try with heat and longer arm for the rachet

will report fir the progress
 
DO NOT USE OPEN FLAM HEAT!!!!!!! Its not worth the risk or burning your ski to the ground ...if you have any gas or oil on the engine or fumes in the engine bay you will have no more seadoo= you very sad
 
Will be watching for your progress report. One final word of caution, do everything in your power not to break one of the bolts off.

Best of LUCK!!
 
TheGunMan said:
Breaking bolt is what scears me to death
Click to expand...

ME TO!!!

I think the factory recommended Loctite on the head of the bolt and grease on the threads. If that is the case then your risk of breakage is somewhat minimized but is still there. Sometime there is a chemical reaction between metals with different alloys causing them to sieze. I hope you get them loose but one thing for sure it ain't no good like it is.:banghead:
 
Unfortunately... bolts break, and there is nothing you can do most of the time. Especially on bolts that have been wet most of their life.
 
The 657X wrist pins are probly gone, as most that year are now. I suggest you break the motor down to a short block and do an exchange.
send your RV cover as it will need machined as well.

Been there, Done that.
 
there is the update:

all the bolts from the top cover removed - heated with hot air gun and then I had luck with all of them

I actualy broke one of the bolts holding the cylinder to the lower part of the engine :(

Here is to ask for the best way to extract the broken part left in there

when I removed the "head" of the cylinders I got instant answer why I am loosing compression. The brutal trooth is that / I am not sure about the order/ the top ring broke /one small part went off/ and then the piston is total damage /see the pic/.

The cylinder itself looks not so bad - no deep marks, just a litle more wear in few places, but not scratched.

Still has to remove the cylinders and then can tell if this is all the damage /hope there is nothing in the lower part of the engine/
 

Attachments

  • piston.jpg
    piston.jpg
    1 MB · Views: 27
You will be in a better position to evaluate that once you get the head off. It will depend on where it broke at. If there is enough to get a hold of it with a pair of vise grips you might be able to turn it out. If it broke at a point where you can't get a hold on it, you will have to drill it out and use an easy out to try to back it out. It isn't easy but is doable.

How bad is the cylinder head? Is it peppered badly?
 
Status
Not open for further replies.

Similar threads

G
Cylinder gasket?
Replies
9
Views
344
mikidymac
mikidymac
L
Help with 2000 LRV
Replies
0
Views
52
LRVlvr
L
D
1995 GTX Won't Rev Out
Replies
4
Views
345
bawray
B
Vanbib
2005 GTI Std rpm issues
Replies
4
Views
231
Vanbib
Vanbib
CorbinSeadoos
Help! No Start, What am I doing Wrong? - 95 SPX Rotax 657x
Replies
3
Views
241
exoh_e
E
Back
Top