Did I check Compression Correctly ?

[oldmanactingyoung]

Hi All

I just wanted to be sure i did this correctly. I have noticed on here that the basics of getting a used seadoo If you have good compression then you have a good base to work with. I purchased 2 used seadoos and want to get them back up to the standards i feel they should be.

They are super clean on the outside so i think the 1st owners took very good care of them. the young couple i got them from did not. they kept them looking good on the outside but not on the inside. they rode them till they had problems then parked them. so i am just checking to make sure I have a good base to work with so i can get them back to where they need to be. I got them Very cheap so investing a few dollars is not a problem.

On checking compression i took plug wire off attached it to the post then took plug out Installed Compression Gauge and bumbed engine one turn got about 140 of back cylinder did same to front and got about 140 from that one also. I did this 3 times on each one and got very good average ( not an expensive compression tester but seems accurate ) then i did same with turning engine over several times and would get 170 to 175 on each. i also did this several times and got same average 170 to 175 from each....which way is correct way to get correct Reading one turn or several ? ...no instructions with Compression Checker so im not sure...any help would be appreciated

 

[oldmanactingyoung]

oh sorry this was on the 95 GTX with 657 Rotax..oh and also something else i was confused about on titles they told me that a seadoo title shows 1 year behind what it actually is lol...Example : if title shows 96 then it is a 97 ?...Ok Ok i know you guys are rolling over laughing right now because im laughing at myself also hehe...i figure they are the year model that the title Reads but i wanted to check and make sure for when i order parts ....so by title this would be a 94 GTX 657 ( thats what title reads )

 

[robin savell lloyd]

I would say to spin engine over wot for 3 to 5 seconds. sounds like you have very good compression or a lot of oil in cylinders.:cheers:

 

[robin savell lloyd]

Not sure about your year but my title reads 1994 and the parts I have to order are for a 1995 as they do not show a listing for a 1994 :cheers:

 

[oldmanactingyoung]

Thank you Robin i read forums and noticed on one it said to hold throttle open all the way also so i went back out and pulled Both plugs put wires on post. ( new plugs by the way and when i pulled them no oil at all on plugs ) and then with throttle all the way open spun them several times each did this test 3 times on each cylinder and got about 170 on each one...

If there was a lot of oil in cylinder would i see it on the plug ?...they are brand new and have not even been run yet. Reason i was so concerned with this is that when i Cranked it i did get a lot of smoke from the rear...and i mean a lot at 1st it started to clear up some after a few minutes but i was afraid to run it more then 5 minutes as i read in here that it is not good to do so with only a hose. I got 2 seadoos used and will have some repairs on them both. i wanted to start with the basics ( compression make sure i had that in good standing ) then work out from there. We are avid boaters and outdoor people and i rented my wife a jetski and she loved it so we got these to play on..

Again Robin Thank You for the help :cheers:

 

[robin savell lloyd]

I would not be to worried about oil in cylinder unless it hydrolocks engine it may be normal for a old ski to smoke bad on first start after it has been stored for a while. :cheers:

 

[seadoosnipe]

Compression gage....

I think you may be right about the "cheap" tester. I think it may be off a little. You shouldn't see anything greater than 155 psi or 160 at the very most.

There are two compression tests that can be performed, a wet and a dry. When Robin mentions oil, he means on the cylinder walls. If the cylinder walls are dry, no lubrication, then you'll likely get a different reading than if you squirt a small dab of oil in them.

Not to worry though, it sounds like you've done the compression test correctly with Robins' help.

Your oil smoke issue will be something to monitor. It's probable that the oil smoke may be from storage or just a small build up from turning the engine over without starting. But be aware that the engine has a chamber between the two pistons, called the rotary chamber. It's flooded with oil and seperated from the pistons by seals. If the ski sat up for a long period of time without running, you may see some of that oil seeping past those seals or they may be leaking more oil than they should. So, for now, don't worry about it. But if it smokes real heavy after running for a while, then you may find that to be your problem.

 

[oldmanactingyoung]

Thank you SeadooSnipe that was one of my concerns there. And now i know what to watch for....i will watch that very close...again thanks for taking time robin and Snipe :hurray:

 

[seadoosnipe]

Thank Robin...

Thanks to Robin, he did all the work. I just kicked in a little snipet.

 

[IMEX]

Hi All

I just wanted to be sure i did this correctly. I have noticed on here that the basics of getting a used seadoo If you have good compression then you have a good base to work with. I purchased 2 used seadoos and want to get them back up to the standards i feel they should be.

They are super clean on the outside so i think the 1st owners took very good care of them. the young couple i got them from did not. they kept them looking good on the outside but not on the inside. they rode them till they had problems then parked them. so i am just checking to make sure I have a good base to work with so i can get them back to where they need to be. I got them Very cheap so investing a few dollars is not a problem.

On checking compression i took plug wire off attached it to the post then took plug out Installed Compression Gauge and bumbed engine one turn got about 140 of back cylinder did same to front and got about 140 from that one also. I did this 3 times on each one and got very good average ( not an expensive compression tester but seems accurate ) then i did same with turning engine over several times and would get 170 to 175 on each. i also did this several times and got same average 170 to 175 from each....which way is correct way to get correct Reading one turn or several ? ...no instructions with Compression Checker so im not sure...any help would be appreciated

Your compression is perfect. Your seond time round was the right way. Keep the tester in the hole and make sure the guage needle cannot go any higher, before you stop the cranking.

 

[robin savell lloyd]

Thanks to Robin, he did all the work. I just kicked in a little snipet.

I do not know if you will find another person then Louis on this site that tries to be respectfull and has a great depth of knowlege and can admit to being wrong which he is not very often. He is truely the most informed among us all. That is only my opinion. and till someone can prove me wrong I will stand behind what I say. :cheers:

 

[seadoosnipe]

Smoke and running...

If you saw a good bit of smoke, this will be cause of a build up in the bottom of the crankcase. You may have a seal in the rotary chamber seeping by just a bit, which isn't completly unusual. Just a "seep" isn't bad. The smoke will eventually burn off.

You can run the Seadoo's longer than 5 minutes if necessary. The "5 minutes" applies to the 4-TEC engines as they have a closed loop cooling system and a shaft seal that is lubricated by water while riding. The seals on the older doos aren't lubricated. They are carbon ring and washer. They aren't cooled by water.

But, I'd say it isn't a good practive to let them run un-necessarily.

 

[oldmanactingyoung]

Thanks guys again u answered it all perfectly. got it running now and the smoke has cleared up considerably....i think it was the seepage from sitting for 2 years and not being run at all....there might be a little seepage as louis suggested ( geez are u ever wrong hehe nah J/k ) but it must be very little as when you crank it now it smokes a bit then clears up after a few seconds...thanks guys