Super Jet Woes. Tech Help and a Beer Needed!

[Mouthfulloflake]

well?

have you taken this long of a break?

 

[Fathom]

well?

have you taken this long of a break?

Actually, I did. I had a well pump take a crap on me so I diverted my attention to it and yard work. I'll try today and post up.

 

[Fathom]

Alright, I just changed the stator again, this time with a known good one from a running motor. I'm getting the same thing. It wants to start so bad. It sputters and every now and then if I feather the throttle, it will backfire so what am I left to do?
Is it possible my crank is not indexed causing the timing to be off so far that regardless of where the stator is set, the timing is off? What's the easiest way to verify indexing/proper crank position?

 

[Mouthfulloflake]

I doubt you can verify that acuratly at all with the engine assembled.

make a mark on the flywheel outer diamter.

but basically put one piston at top dead center ( as high in the plug hole as you can get it)

mark that position on the engine case relative to the mark on the flywheel.

do the other piston, they SHOULD be 180 apart right?

im not sure if you can measure this accuratly enough like that though, im also not sure that being out of phase that much would prevent the engine from running.

man.. im nearly out of ideas.

150/152 compression, reeds are sealing, carb substituted, stator substituted, strong consistant blue spark, exhuast not blocked.. that doesnt leave to many things that are common problems that I am aware of.

:frown:

Alright, I just changed the stator again, this time with a known good one from a running motor. I'm getting the same thing. It wants to start so bad. It sputters and every now and then if I feather the throttle, it will backfire so what am I left to do?
Is it possible my crank is not indexed causing the timing to be off so far that regardless of where the stator is set, the timing is off? What's the easiest way to verify indexing/proper crank position?

 

[Fathom]

New twist, the wife and I were brain-storming over a smoke and a pancake. I had not verified the compression since it stopped working. I had done it prior ro purchase and prior to start. I thought, "Why not check it again, real quick like?"

Hook my guage to it and I get 40 or so PSI. Check the other, same 40 PSI. I pulled the head and there is no obvious issues with the top end. Pistons appear to be intact and there is zero scoring.

What else could cause a near total loss of compression? I actually feel good knowing now it's a compression issue and no longer an electrical/fuel issue.

 

[Whtbread]

Maybe a stupid question but are there rings on the pistons?

 

[Fathom]

There's rings on the pistons. I had 150/152 compression at one time. My guess is once it started, I blew a crank seal. From the looks, the rear and front look good but only disassembly of the case and crank will tell me for sure. Anything else it could be considering compression dropped in both at the same time? I wish I had rechecked compression earlier.

 

[Mouthfulloflake]

put some oil in the plug holes and check compression again.

im not sure that a crank seal would such a dramatic effect on the compression reading?

stock head or aftermarket?
gasket or o rings look ok?

for BOTH cylinders to drop seems strange to me.

There's rings on the pistons. I had 150/152 compression at one time. My guess is once it started, I blew a crank seal. From the looks, the rear and front look good but only disassembly of the case and crank will tell me for sure. Anything else it could be considering compression dropped in both at the same time? I wish I had rechecked compression earlier.

 

[Fathom]

Stock head. Gasket looked great.

 

[Fathom]

Was speaking with Derm here locally. He doesn't think it's a crank seal either. He's thinking its the head gasket and I'm getting crossover between the cylinders. I checked the ports and brought the pistons to TDC and have next to no slop and the pistons recenter themselves as they should. I also checked the head for warpage and it's straight.
I'm in the process of prepping the gasket mating surfaces now. I'll lightly coat the cylinders and drop a new head gasket on and recheck compression.

 

[Mouthfulloflake]

I think at this point you need to measure piston and bore.

IM wondering if you had a lot of lube in there intiitally to get that 150/152 reading, and it was the oil or storage lube alone giving that compression.

possibly the ring/bore seal is just wore the hell out?

was it suppsoed to be "new" or "used" or what>?

Was speaking with Derm here locally. He doesn't think it's a crank seal either. He's thinking its the head gasket and I'm getting crossover between the cylinders. I checked the ports and brought the pistons to TDC and have next to no slop and the pistons recenter themselves as they should. I also checked the head for warpage and it's straight.
I'm in the process of prepping the gasket mating surfaces now. I'll lightly coat the cylinders and drop a new head gasket on and recheck compression.

 

[Fathom]

When I got the ski, it was someones old project and part of a court ordered division of property during a divorce. I have no history of the ski and no way to contact the previous owner. All I could do is go over it and see what I needed, one item at a time. It had a seized pump which I replaced and while I had the pump out, I spun the motor by hand, did a compression check and got good readings. It was missing a tank and other bits and pieces so it was to be some time before it would be up and running. I coated the cylinders with a small amount of oil and cycled the motor over by hand until it would be up and running. Once all the parts were gathered and installed, I went for the start and history was written in post #1.
After changing the head gasket and attempting another compression check this evening, I ended with the same disastrous result and the motor is now sitting on the bench. I see no obvious reason for the lack of compression. I was hoping for an obvious crack in the jugs so at least I would know where to go from there. Derm told me he wants to take a look at it before I pull the jugs. Heck, I don't know at this point. SBT is starting to have a nice ring to it.

 

[Mouthfulloflake]

you should sell it to me for dirt cheap, Ill fix it.

:Banane01:

 

[Fathom]

you should sell it to me for dirt cheap, Ill fix it.

:Banane01:

:bs2: :lightning: :smashfreakB: :starwars: :spank: :twak: :censored:


:Banane35:

 

[SkiDaddy]

Maybe it has the wrong size rings and/or pistons for the bore?

 

[Fathom]

I doubt it. I mic'd it and it looks to be a stock bore. From the looks of it, I was the first to open it up.

 

[SkiDaddy]

Are the rings locked up in their grooves?

 

[Fathom]

I'm thinking not but I haven't got the cylinders off yet. The pistons recentered themselves as if they were free but I can't be sure until disassembly. I'll be sure to post what my findings are.

 

[Fathom]

Okay, I think now that I've got the cylinders removed and had a chance to look the internals over, I may have found good reason for my lack of compression. On each piston, the rings are stuck at one end and not free to move entirely. The edge of the ring nearest the tiny roll pin is tight in the groove. I don't think this is normal but I can't easily get it loose either. Is it normal? If not, what's the remedy? Can I use a scribe and pull the edge out and be fine? If this is not the cause, I'm baffled, still.

 

[Mark44]

Looks like you are on to something.

Mark44