Bonmotwang
Well-Known Member
Just Did a quick test Mag 130psi. PTO 127PSI, before I add 10ml XPS into each hole.
When it was doing PTO. The needle was hitting 131PSI then sit back at 127PSI when I stop cranking.
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2001 Seadoo Sportster LE. Just got it!
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Just Did a quick test Mag 130psi. PTO 127PSI, before I add 10ml XPS into each hole.
When it was doing PTO. The needle was hitting 131PSI then sit back at 127PSI when I stop cranking.
Waterluvr
New Member
So the psi should never go backwards on a compression tester, I would replace the shrader valve for good measure and would expect your readings to climb right away.
Sportster-2001-951C-Stock
Well-Known Member
Agree, maybe the schraeder valve is not tight or the hose is leaking b/c the gauge pressure shouldn't drop from the peak.
Sportster-2001-951C-Stock
Well-Known Member
Looks like you just proved we should be blowing 130psi.
Sportster-2001-951C-Stock
Well-Known Member
Retorque the cylinder and head studs now, just to be sure as the gaskets relax the clamping force is maintained.
Bonmotwang
Well-Known Member
It is amazing that my old pistons hold the compression at 110/120PSI. The rings were doing the job even the pistons were "rocking" in the hole. I cannot "rock" the new piston.
Edit: almost wanted to say 951 is well designed :-D
I was looking at those tiny oil lines when carbs are out and tuned pipe not in the way. But didn't get a chance to talk about replacing them. Did check oil dripping or leak around the area, no evidence of cracking.
Bonmotwang
Well-Known Member
Forgot it mention a detail I noticed when out in the water:
I removed the raves and was cranking the flywheel by hand, watching the piston though rave opening. I heard air leaking/squishing sound every time when the rings passing/closing the exhaust port. Almost tells me there is a small gap just above the exhaust port?
I removed the raves and was cranking the flywheel by hand, watching the piston though rave opening. I heard air leaking/squishing sound every time when the rings passing/closing the exhaust port. Almost tells me there is a small gap just above the exhaust port?
Bonmotwang
Well-Known Member
Another one: I may have over trimmed the raves by 0.3mm. Was so worried about rave blade touching the piston. By looking at the exhaust port it shouldn't change the air passage too much. Or it will affect the performance?
Waterluvr
New Member
I don't know if he has access to a Snap-On dealer up there but their p/n# MT24DA1 is the very best valve I have found for replacement in a compression tester and they are cheap ($1.10 US) each. They have the white lower valve body, I find they give much more accurate readings.
Sportster-2001-951C-Stock
Well-Known Member
I think you are okay if the engine starting and low speed operation remain acceptable, if the RAVES are trimmed too much then it will negatively effect the low speed operation.
Worst case occurs if the rave shaft breaks, then rave can fall into the cylinder.
Sportster-2001-951C-Stock
Well-Known Member
3/32ID Tygon F-2020-A, I haven't replaced mine yet either but probably should.
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Sportster-2001-951C-Stock
Well-Known Member
Maybe I should remove and clean the schraeder in mine, I don't think it's ever been removed but I'm sure I've tightened it at least once, probably when I bought the gauge circa 1980!
I've also replaced the o-rings a few times since then.Sportster-2001-951C-Stock
Well-Known Member
This sounds like normal leakage past the rings to me, you will normally see some of this. Maybe it improves some as the rings begin lapping to the cylinder and the hone marks are worn down.
130 sounds like you have a nice tight compression chamber, it may even increase a couple of psi after a few hours.
Waterluvr
New Member
I'm thinking he will notice a difference when he finally bury's the throttle and stay's in it for a bit.
Sportster-2001-951C-Stock
Well-Known Member
I'm thinking he will notice a difference when he finally bury's the throttle and stay's in it for a bit.
Agreed, that should prove interesting.
Bonmotwang
Well-Known Member
Never ever tried WTO on my boat :-D
Always do WTO on a rental. The best ski trip was at myrtal beach with a guide. Two guys flying through the ocean. Somewhere close to shore only 8 feet of water opening. He asked me to stay right on his trace.
Bonmotwang
Well-Known Member
Was doing 6500 RPM planing for long time in the morning after 30 minutes warming up. Hitting 7000RPM a few times.
The oil light turned on at 2" from the bottom. So oil sensor is working too. I got 500ml with me so added it in.
The oil light turned on at 2" from the bottom. So oil sensor is working too. I got 500ml with me so added it in.
Waterluvr
New Member
Got the kids out with you today? Might as well ready the tubes and ski's again while there's a few weeks of summer left sounds like it's running great.
Congrats man, job well done.
Bonmotwang
Well-Known Member
No tubing today. But weather is gorgeous. A lot of jumping wakes. Kids are yelling "faster, faster" and she kept up!
You know what? Do you remember my wife's August 2nd event with her friends. Yes. I made it
You know what? Do you remember my wife's August 2nd event with her friends. Yes. I made it
Bonmotwang
Well-Known Member
Thanks man. Really really appreciate all the help.
Waterluvr
New Member
No tubing today. But weather is gorgeous. A lot of jumping wakes. Kids are yelling "faster, faster" and she kept up!
You know what? Do you remember my wife's August 2nd event with her friends. Yes. I made it
I absolutely remembered that from before, not only did you fix your own boat but managed to keep the wife's plans afloat. I'd say your winning all the way around on this repair job.
Sportster-2001-951C-Stock
Well-Known Member
I'm thinking he will notice a difference when he finally bury's the throttle and stay's in it for a bit.
Sounds like that happened today, the kids demanded it. And it stayed together so all is well.
Good job!
Bonmotwang
Well-Known Member
Thanks Sportster, Water lover, and all other members, visitors. I treated it as a teamwork. Even though we are probably 1000 miles apart
Cheers Team!:cheers:
Yes. cannot resist when kids are excited. This is the boating all about, at least to me. Yesterday we have one teenage, and 4 kids, and some adults. I went back and forward to switch people several times.
They all enjoyed and loved it. All good.
I checked the engine in the morning. Opened the Rave's, the blades have less black oil now (it was almost dripping in the break in) and same amount on both sides, no chocolate milk (wondering what was this thing in the first hour of break in?).
Looked into the Raves, the pistons are clean with a few scratching lines, not straight, probably from the installation. that black Teflon coating on the piston skirt has gone. Not sure why they put it there. Even I was testing the fit on the bench, the black coating already got scratched off a lot. I have never done this Rave check before, so I have no reference to compare, The rings are shiny, the pistons look "dry" to me, again I have no reference to the oil engine checked after running before adding oil.
Should I expect to see the piston is visually covered with oil and look "wet"?
Checked the spark plug, not oily wet, but with some small hard black particles (around 0.004" size) on the insulator and also a bigger piece on the "hook". Is it carbon residue?
Then I added oil, through the Rave, which I considered a better way, because you can see the piston
Did a compression test, PTO 130PSI, MAG 150PSI. A little surprised by the difference. But I always had a feeling that MAG side is "better" PTO side :-D.
Then cranked the engine a few seconds more for a couple of times, then did the test again. now PTO 135PSI, MAG 140PSI, test it again. both at around 140PSI.
Next time I should bring the compression tester on board, so that I can have some result from a hot engine.
I am thinking about getting a ski with 951 now. so that I can play a little more. That's the problem when you know a little about the things but don't totally understand, and getting dangerous. :willy_nilly:
I am watching for the skis for sell in the US now. Even it is for a project with fairly solid starting point.
Now I made the pressure gauge, I should change my pump cone pressure again. Last time I "couldn't" get the needle bearing pushed out and didn't change the shaft. and the shaft did have some grooves on it.
The only thing I changed last time is the thrust bearing and the washer.
I will order a new shaft. this time I will change the needle bearing, shaft, and seal, which is a real rebuilt.
Guest_User
New Member
putting oil in the cylinder or on the piston is skewing your comp test numbers!!!
you are filling the cross hatch lines with oil creating more of a complete seal... no matter how many times you crank it after wards...
Cold engine, throttle open fully, crank for 5 revolutions and look at the gauge... that is your number...
I don`t recommend doing a hot test at all... I never pull a plug from a hot aluminum head ever, regardless of what you read or hear... always try and do what you need to do to a cool engine...
spark plug torque values are different from ambient temps to hot, and you don`t want to stretch or strip the plug threads in the head...
you are filling the cross hatch lines with oil creating more of a complete seal... no matter how many times you crank it after wards...
Cold engine, throttle open fully, crank for 5 revolutions and look at the gauge... that is your number...
I don`t recommend doing a hot test at all... I never pull a plug from a hot aluminum head ever, regardless of what you read or hear... always try and do what you need to do to a cool engine...
spark plug torque values are different from ambient temps to hot, and you don`t want to stretch or strip the plug threads in the head...
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