Snowmobile Forum banner

1 - 20 of 33 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
I just bought a used 2001 Ski Doo Deluxe 500 for a summer project.
First thing that got fixed was the ignition and I checked to make sure both plugs provided a spark, which they did. I then tried to start her by spraying starter fluid into the carb. I got nothing so I next tried putting some in the spark plug spot spot and then tried. Nothing again. Im kinda stumped and dont know where to go next, I just need her to turn over once before i re hook up the fuel pump and fuel lines.

I can post pictures and videos if anyone wants to see.
 

·
Super Moderator
Joined
·
100 Posts
If it's not firing with Starting fluid then you had better check compression as well. Check the spark again of course too.

Steve
 

·
Registered
Joined
·
11 Posts
Discussion Starter #3
Is it possible that if its not getting a good seal it wont even fire once or twice, because i know the sparks are fine.
 

·
Registered
Joined
·
1,032 Posts
Btw use gasoline not starting fluid when trying to start 2 stroke engines. Starting fluid is made for Diesel engines. Just drop a ounce or two down the each cylinder hole and go from there. Check compression as steve said. Anything under 110lbs and I would be looking at least a top end rebuild.
 

·
Super Moderator
Joined
·
1,862 Posts
I would one up that thought with a pop bottle of gas and OIL and then add a tip to it from a gear lube bottle to squirt it into the plug holes.
I had one made up for the Old Bravo before I added the primer.
 

·
Super Moderator
Joined
·
17,170 Posts
Also, most newer diesel engines, especially those with an intake heater (Cummins, Duramax), specifically state NOT to use starting fluid. If the intake heater is hot enough, the ether in the starting fluid can blow up when it hits the heater. That can ruin your day (as well as your intake!)

Most starting fluid you find has "top end" lubricant in it so it is a bit safer to use to start small engines. While a steady diet of the stuff is not a good idea (gas/oil mix in the plug holes is way better) I will use it from time to time.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #7
I have pour a little gas in the top with no success, is it possible with that the timing is wrong with the spark plugs? I'm going to check engine compression tomorrow to make sure that isn't an issue
 

·
Super Moderator
Joined
·
17,170 Posts
Timing doesn't go out often. In order for that to happen, the crankshaft would have to be twisted out of phase, which can happen but is very rare. If you have fuel and spark, my bet is on low compression. There could also be other mechanical damage such as a broken piston skirt that will cause a no-start, but usually you would be able to determine that pretty easily.

You can check some things by pulling the plugs out and using a small light to look in the cylinder. Put the piston to bottom dead center and look at the piston crown. You are looking for holes or obvious damage, especially on the exhaust side. You may also be able to see any big gouges in the cylinder walls which could indicate an upper engine problem.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #9
Ok It was missing some top case bolts so i bought some and tightened them all down, so i think compression's are good. So i took some pictures and nothing looks wrong to me, except one of the pictures is looking through the carb tube and I noticed that when the piston head is at its lowest point you cant even see into the cylinder. Is that normal? (I attached a picture of it) After i Tightened everything down I put a little gas in through each spark plug spot and tried to start her with no luck. I'm going to buy a compression check tool just to make sure that it isn't that.
 

Attachments

·
Registered
Joined
·
3,587 Posts
Pictures 3 & 4 are strange. Maybe just an optical illusion? Looks like something sticking into the cylinder holding the rings away from the wall??
 

·
Registered
Joined
·
11 Posts
Discussion Starter #11
Took a compression check it read 75psi and held it. Im going to try and take her apart in the coming days to see if any gaskets are missing or damaged.
 

·
Registered
Joined
·
1,032 Posts
75lbs is waaaaay to low, you need at least 110lbs on each one. You are looking at a top end rebuild with pistons, rings, gaskets and at least a hone job. Bear will help you a lot with all of that stuff and what companies work best.
 

·
Super Moderator
Joined
·
1,862 Posts
First did you hold throttle wide open?
Did you give it like 10 hard pulls each?
At 90 psi you could have a hole in piston!
 

·
Registered
Joined
·
3,587 Posts
Just looking at the pictures, it looks like a collapsed ring.
 

·
Registered
Joined
·
1,032 Posts
That is what I kinda thought as well Bear. Those pictures something just looks off like it is sticking out of the side. I would be amazed if there wasn't some more damage below it. I would yank it all apart hope and pray I could get away with a really good hone job and go from there.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #16
Ok I have started to tear her apart and there is a metal ring directly under the top case and i pulled the ring out and there seems to be an o-ring along that but no gasket. Is that how its supposed to be? (one of the pictures has the ring and the other doesnt.) Im going tot continue to take her apart, im looking at taking it out so its easier to work on, but im not seeing any holes or cracks so far. For some background I bought this for 100$ as a project. If the wiring has anything to say its some pretty red-neck handiwork the last guy did to it so im hoping he just screwed something easy up.
 

Attachments

·
Registered
Joined
·
3,587 Posts
Hmm
 

·
Registered
Joined
·
11 Posts
Discussion Starter #18
Alright so i took of the case and took a closer looks at the pistons and everything looks fine. No scratches, dings, dents, etc. Also looked again inside the cylinder nothing again. Are thoose 2 metal rings what keep the seal between the piston and cyclyinder? Also are there supposed to be gaskets between the crankcase and cylinder, because there wasnt.
 

Attachments

·
Super Moderator
Joined
·
17,170 Posts
The two rings on the piston are compression rings and that is what gives compression in the engine. If you can remove one of the rings from the piston and place it squarely back in the cylinder, you can measure the distance between the ring ends. If it's out of spec, that would indicate either the rings are worn or the cylinder is worn. Most of the time, if it's a "lined" cylinder, the rings wear, as the nikasil lining is very durable.

Most of the time, snowmobile engines that have low compression from worn rings get new rings and pistons, as that may indicate the piston is probably too fatigued to put new rings on. As the piston moves in the bore, there is a bit of rocking motion which can introduce fatigue on the piston skirt. You won't know the fatigue is bad enough to break the piston until after it breaks. If I were to tear down an engine to this extent, it gets new pistons/rings as a matter of course. They are not that expensive and new parts give a much better feeling of confidence in the engine.

Here's a short Youtube video on checking ring gap, there are many others on Youtube to guide you.

 
1 - 20 of 33 Posts
Top