93 ext 580 Piston Help... - Snowmobile Forum: Your #1 Snowmobile Forum

Dennismc · 10-25-2007, 10:40 AM

Ok, Replaced the pistons last year, maybe have around 50 miles on them. Saw a little shinny area when replacing the plugs and decided to take a better look.

These are what they look like now, I am going to go compare them to the thread on pistons, but also wanted to ask the pros here what they think of them? Are they normal? Not good? etc....

BC_Dan · 10-25-2007, 11:00 AM

The piston on the left looks pretty close to what you want, the one on the right looks REALLY rich. The unburned fuel flowing into the cylinder over the piston from the ports washes the piston clean, the one on the right has a TON of piston wash. I'm wondering if the jet is the right one, or if it fell out...

Dennismc · 10-25-2007, 11:08 AM

Ok I will check that, also I just noticed while inpecting the o-rings on the cyl cover. that the center one seemed FLAT on the cyl, could that also be due to antifreeze getting into the cyl? Remember this sled SMOKES all the time Really bad, unless I am moving

IndianRvrShiver · 10-25-2007, 11:38 AM

Maybe it's just an illusion, but looking at the 1st pic....at 3 o'clock & somewhat at 12 o'clock...is there some erosion to the edge of the piston??

Dennismc · 10-25-2007, 11:48 AM

IRS, I will have to tear it down again and check, I dont remember seeing any, I did wipe it down some since some antifreeze got on it, but I will check that again now.

Update:

Ok pulled the cover and took a couple more closeups. If by erousion you mean the carbon burning off, then yes, the piston itself is fine, but the carbon build up has burnt off on that section.

Is that something as well I should be concerned with?

BC_Dan · 10-25-2007, 05:42 PM

You are looking for some piston wash, an area about the size of a thumbnail or a little bigger at each intake port would usually be safe. If you have carbon from edge to edge on the piston top, with NO areas cleaned off by fuel entering the cylinder, you would be too lean and take a chance of burning holes in your pistons.

Dennismc · 10-25-2007, 06:20 PM

Ok so dan, the one on the left in the first group is ok, the other side, is the problem.

Think i narrowed it down to antifreeze leaking in, the center o-ring was bad. SO I am thinking getting some antifreeze in there and that is cleaning the piston, as well as causing the smoke issue..

Goiong tomarrow and picking up new rings for both sides and re-seating them.

BC_Dan · 10-25-2007, 07:48 PM

That would do it

You can check plugs too... look for a cardboard brown color, if it's lighter than that, jet richer, if it's blacker than that, you can safely jet leaner. I don't know if your book says to, but when I redid both my old ZR's, I coated the o-rings with grease to make 'em stay in the groove. Pesky little things, they are!

FoxLakeRider · 10-25-2007, 08:42 PM

I would second that Grease is great to make em stay they are allergic to the aluminum it seems! HAHA

Jim Jessup · 10-28-2007, 02:41 PM

I would agree, the first thing I noticed when I looked at the photo with both cylinders grouped was that bad o-ring. Had this problem on a Rotax engine.

Dennismc · 10-31-2007, 08:11 PM

Ok guys UPDATE here.

I replaced the center o-rings on both sides, and it ran great, less smoke even..

BUT I forgot to refill the coolent right away and it overheated, shut her down Instantly.

Now the starter side is not firing at all. It has spark, (no spark tester but if I put that wire on the other side she runs on that one cyl.)

She is getting fuel, plug comes out wet and if I pull it without the plug in it, it shoots it out.

Swapped the cdi out and no differnt, tried a differnt ing. coil. same problem.

Any ideas here? I am stumped beyond stumped...

thanks
Dennis

BTW putting the down payment on my 02 zl600 esp this week, will have it for the trip!

Jim Jessup · 10-31-2007, 09:26 PM

Did you install new plugs? If it fires on the other cylinder it has to work.

FoxLakeRider · 10-31-2007, 09:32 PM

Yes start with plugs they are finicky

Dennismc · 10-31-2007, 11:03 PM

Two brand new plugs.
Even at one point swapped the plugs from one side to the other

FoxLakeRider · 11-01-2007, 12:44 AM

You had a rich problem before on that cylinder yes? did you figure that out? If you are flooding it it wont fire that side My 580 did that... also be absolute sure you have spark in that hole.. pull plug put in boot and ground it to head bolt and turn over you will see it it you do I no you said you did but be for sure... if you do and you are not flooding it with gas it should fire up..

Keep at it snow is a coming!!!!!!!!!

Dennismc · 11-02-2007, 04:21 PM

Didnt have a rich problem, was leaking antifreeze into the cyl...

Here is a shot of the inside of the cyl that isnt firing, it looks to me like scoring on the cyl. walls, not enough to feel with my finger but I dont think it was there before. *see pics

Oh and yes I know, need another inner ring, that is what happened as soon as I pulled the cover..

EDIT:

It would help if I actually finished my thought in the post.

What I am thinking is that when it overheated, that side's piston rings got messed up and is causing problems, like not firing even though there is fuel/air and spark

Jim Jessup · 11-02-2007, 05:39 PM

Looks like its time to do a compression test. I don't think you have to replace the o-ring unless its damaged, and in your case very little use. But when you put the engine back together for good it probably wouldn't be a bad idea.

Dennismc · 11-02-2007, 05:50 PM

thats what I am thinking as well, but as for compression, if it is low, where would it be coming from? Rings? there are no other leaks that are visable.

Jim Jessup · 11-02-2007, 05:55 PM

If it' low(note that I am not saying that it is low). It would probably be piston and rings, in combination from rubbing the cylinder when it got hot. From the photos your cylinder looks like it would only need a honing(if its not out of round or out of spec).

Dennismc · 11-02-2007, 06:18 PM

Great thanks. Guess its time to break down and spend the 30 bucks on a tester

Also, what should the compression be? and if it is low, what should I be looking for for the cause?
If rings, what signs that they are bad?