Lost compression on my wife's pink sn

[McDog]

I put total loss on this ski a few weeks ago and couldn't get it to run right. The spark didn't seem right. No throttle response. Would go dead and not start for a while. Checked compression and changed coils a few times. Then it suddenly wouldn't start at all. Timing light showed no spark or off time sparks. Figured it was a bad brain. Maybe it was, I don't know.

Switched it out to a known working stock ignition today and it still won't start. Spark is there with a timing light. Spark....check. Gas via primer.....check. Compression?.....no, I just checked it last weekend......WTF! 25psi in rear cylinder. WTF!?

LPW ported 61x 701 cylinder with Wiseco pistons. Turns over smooth.

I have a black cloud over my head this year.

Question is was it the total loss that caused it or was it coming anyway?

Likely problems are....?...bad rings? hole in piston?
​

 

[Waternut]

My money is on worn o-rings in the head. So out of the 5 boats/ski's that you have, 2 work right now? lol

 

[McDog]

Sad, isn't it. I'm a full time mechanic who obviously sucks.

 

[ATS_Aaron]

Pull the head and take a look.

Aaron

 

[McDog]

I sure hope it's just an o-ring. Have guests arriving for a day on the lake. I'll have to check it tomorrow.

 

[sportfish258]

Tell them to stay home . I hate having guest 's down........... too much trouble ..... something always breaks down , gets scratched up , tracked up floors ,tangled rods on and on ... when they leave everything has an empty tank and is dirty.

 

[Waternut]

Tell them to stay home . I hate having guest 's down........... too much trouble ..... something always breaks down , gets scratched up , tracked up floors ,tangled rods on and on ... when they leave everything has an empty tank and is dirty.

Man your guests suck... Do you have a bunch of 5 years olds over all the time?

 

[Big Kahuna]

I put total loss on this ski a few weeks ago and couldn't get it to run right. The spark didn't seem right. No throttle response. Would go dead and not start for a while. Checked compression and changed coils a few times. Then it suddenly wouldn't start at all. Timing light showed no spark or off time sparks. Figured it was a bad brain. Maybe it was, I don't know.

Switched it out to a known working stock ignition today and it still won't start. Spark is there with a timing light. Spark....check. Gas via primer.....check. Compression?.....no, I just checked it last weekend......WTF! 25psi in rear cylinder. WTF!?

LPW ported 61x 701 cylinder with Wiseco pistons. Turns over smooth.

I have a black cloud over my head this year.

Question is was it the total loss that caused it or was it coming anyway?

Likely problems are....?...bad rings? hole in piston?
​

If your timing was off then it may have messed up a piston.

 

[McDog]

It was 29 degrees advanced with a timing light when I first hooked it up. 5000 start retard. 9000 limit. 3/1000 retard rate. It was an analog brain and those were the only modules I could find.

 

[TJLSuperJet]

my ski did something like this not too long ago, it was cranking with no spark, I checked everything before I found the problem... it was the start stop switch. I gave up on trying to figure out why, ended up putting some quick connects on the wires going to the switch and when I unpluged the stop wire, it fired right up.... :starwars:

 

[McDog]

The ss switch has been acting screwy. I have another one on the way. It has bullets on it now so disconnecting the stop would be easy. Is the red one the stop?

 

[Matt_E]

Black & white are the stop switch wires.

 

[McDog]

NO such luck on the 0-rings.

This might explain why this cylinder kept fouling plugs last year. That was the reason I switched it to total loss in the first place. I figured something was wrong either with my coil or cdi. I guess not.

Do you think the ring caught on the exhaust port? Porting issue? Something else?

The cylinder isn't even scored.

Just replace the rings and piston or do a whole top end?

 

[deftons56]

damn that sucks, on the upside does this mean your total loss is still good?

 

[McDog]

I hope so.

 

[ger87410]

Mcdog, where'd that chunk of the ring go to?

 

[McDog]

The ring is still there but bent. There is a chunk missing from the piston between the rings and above the top ring where it is bent up. My dome still looks perfect too so I guess it all went straight out the exhaust port. I got lucky there.

 

[ger87410]

The ring is still there but bent. There is a chunk missing from the piston between the rings and above the top ring where it is bent up. My dome still looks perfect too so I guess it all went straight out the exhaust port. I got lucky there.

OIC

IMO, look real good in the case for that missing piece, or pieces if it got eaten up.

 

[Waternut]

If anything, the ring would've snagged on the bottom lip which I would certainly think is unusual. You'll need to check the tolerances on the cylinder itself and see if it needs to be bored up. If it does, that will certainly answer your question of whether you can replace both pistons and rings or just one. Either way, I would personally replace both just to call it good for years to come.

If the tolerances check good, I've got a hone and we can clean up those edges so it doesn't happen again.

That sucks man... I guess 2 years ago was my sucky year, last year was gregg's, and now it's your turn. lol I just hope the cycle doesn't repeat...

 

[ATS_Aaron]

That is a lean melt down, not a snagged ring. A snagged ring does much, much more damage. The edge of that piston melted. Is this a dual carb ski? What is your jetting like?

Aaron