Stuck piston rings????????

[george3405]

Okay, I'm thinking my problem with not starting, only loud backfire, could be stuck piston rings in # 1 cylinder on my 1989 48 SPL. The cylinders are not scored and awhile back the previous owner's gas had become highly contaminated with water. In attempting to start the engine I'm thinking maybe the rings got wet and stuck. Number 2 cylinder compression is good, but # 1's is lower enough to make me think that the intake fuel is getting past #1 piston and exploding in the exhaust. Does this seem feasable. I think I've exhausted all other possibilities. Does anyone know of any techniques to free up the piston rings without a total tear down? I have the head off now so I know timig and cylinders are correct and there are only two cylinders and the wiring is correct. The carbs have been rebuilt, new fuel, and new powerpack, coil, plugs and wires. Also flywheel key appears good with no slippage. Sorry for having to come back here so often, but this has been a tough repair.

Thanks for all of your patience and help,
George3405

 

[Barnacle_Bill]

Re: Stuck piston rings????????

For a start what are your compression readings?

 

[george3405]

Re: Stuck piston rings????????

It has been a couple of months since I did a compression test, but I do remember there was a significant difference between #1 and #2 cylinders. #1 was the low one. I have since removed the head so I don't know if I can get another accurate test with the old head gasket.

 

[HighTrim]

Re: Stuck piston rings????????

A decarb has been know to free up rings and increase compression, but how much difference are we talking about here? Refer to the FAQ for instructions.

 

[MikDee]

Re: Stuck piston rings????????

A loud backfire could be a broken, or hung open reed valve.

 

[CharlieB]

Re: Stuck piston rings????????

Let me see if I have this straight

The previous owner had water in the fuel, enough thaat it quit running, and hasn't run since

Now it's yours, and it still won't run

Right so far?

When all else fails, read the directions.

They only 'backfire' out the exhaust when the timing is way off

Sheared flywheel key, which you already checked,

Ignition module X-firing, rare, but happens,

Previous owner inadvertently switched plug wires, I see about twice a year.

Check the book

 

[george3405]

Re: Stuck piston rings????????

When I put the power pack in I did not get the coils lined up perfectly so the flywheel rubbed a small spot on the exterior of the power pack. It didn't seem to be deep, but could that have caused a problem?

Actually, the previous owner had it running great and tied it up and 2 weeks later it would not start. The coil and powerpack were bad and there was so much water in the gas I could not smell gas at all. That's where I got it.

Thanks,
George3405

 

[george3405]

Re: Stuck piston rings????????

Bump:
Could the timer base be defective. I did have one wire for the new power pack that was skinned (insulation). Could this have damaged the power pack. What does the timer base do and where is it located please. Timing must be way off or a wire shorting. I've checked all, but don't see it. Which wire goes to which wire from the power pack to the sensor/stator (white/black and black/white. Sorry for rambling, but I really want to get this longtime problem fixed!

 

[iwombat]

Re: Stuck piston rings????????

Massive carbon build-up to the point where you get glowing carobon deposits can also cause backfire. That would only happen with a warm engine though. Before you go any further I'd seriously suggest a decarb for a whole variety of reasons, if it'll run that long.

 

[george3405]

Re: Stuck piston rings????????

The problem is it won't run at all. It just backfires loudly out the exhaust when I crank it over. By the way, when I had the head off there was little carbon build up at all on the pistons.

Thanks,
George3405

 

[iwombat]

Re: Stuck piston rings????????

In that case, either your powerpack is firing both coils at the same time, or you've got the wires to the coils hooked up backwards.

 

[george3405]

Re: Stuck piston rings????????

Excellent thought! I bought a Sierra powerpack. Do they get defective and fire both coils at once? It well could be. How can I check that?
Thanks,
George3405

 

[iwombat]

Re: Stuck piston rings????????

You can check that by placing timing marks on your flywheel and hooking an inductive timing light to each plug wire. If cylinder #2 fires on cylinder #1s mark you've got a bad power pack. You can do this with the fuel unhooked, and sparkplugs out to get a bit more rpms for your test (ground the plug wires though).

 

[CharlieB]

Re: Stuck piston rings????????

When I put the power pack in I did not get the coils lined up perfectly so the flywheel rubbed a small spot on the exterior of the power pack. It didn't seem to be deep, but could that have caused a problem?

Actually, the previous owner had it running great and tied it up and 2 weeks later it would not start. The coil and powerpack were bad and there was so much water in the gas I could not smell gas at all. That's where I got it.

Thanks,
George3405

You really need to get ahold of a DVA Meter and the CDI troubleshooting directions

www.rapair.com

follow the links to the CDI online troubleshooting and print the pages that apply to your motor

If the 'gouge' is not into the circuitry you MAY get lucky and epoxy over it, but it may not be the box that is failing, follow the directions and verify the timing as iwombat said

 

[george3405]

Re: Stuck piston rings????????

Iwombat, thank you so much. I went to check the firing of the plugs to see if the powerpack was firing both cylinders at once. Much to my surprise I found that the #1 cylinder was firing when #2 should have been and vice versa. The wiring to the coils is such that you cannot reverse them because of their length, but somehow the wiring was reversed. Before I tried reversing the plug wires, but it still backfired. I "assumed" the wiring was correct. Then I changed out the bad gas and a few other things and never rechecked the firing order. I still have to install a new head gasket and a few other things, including changing out the gas again. When I get everything done I think it will run and I will report back to you all. I thank all of you for your time, your help, and your patience.

Thanks again,
George3405

 

[iwombat]

Re: Stuck piston rings????????

Well, that's certainly a recipe for a backfire. Glad it was that simple.