Snowmobile World banner

1 - 13 of 13 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter #1
I just got a really nice looking excel 3 for a mere $40!
I put fresh gas in it and it started up and idled nice...then I drove it about 10' and stopped and then it started to smoke, and then it slowly died. I checked out stuff for a few minutes and then started it again...I had to give it some gas in order for it to start. I tried to drive it again but this time the smoke was worse and it didn't want to rev above 3k rpms.

Looked at the plugs and both are black. They have black fluid on them that you can wipe off.

The guy who sold it to me said he was driving it last winter and then it died and he saw that the plugs were fouled. He parked it and didn't touch it after that.

I know that running rich will foul plugs...but since the previous owner said it was running and then fouled the plugs that would lead me to think the problem is somewhere else.

Can the injection system on these break in some way that would cause them to dump far to much oil into the gas?

Also, where the carb mounted to the intake is not a solid mount. There is a rubber boot that is attached to the carb and it just kind of sits over the intake's opening. Ill try and take a pic, because it doesn't seem right to me. The rubber boot has holes were it looks like it should be bolted to the intake.

If it is a problem with the injection system, how hard is it to bypass it and just mix the gas?
 

Attachments

·
Registered
Joined
·
16 Posts
Discussion Starter #2
anyone know if the oil injection on this sled lubes the crank?
I read that ones that do cannot by bypassed.
 

·
Registered
Joined
·
1,352 Posts
Usually, if the oil pump lubes the crank, there will be lines going from the oil pump to the crankcase ends. If you only have two hoses that go to the carbs, all the oiling is done as the fuel mixes with the intake air.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #4
Usually, if the oil pump lubes the crank, there will be lines going from the oil pump to the crankcase ends. If you only have two hoses that go to the carbs, all the oiling is done as the fuel mixes with the intake air.
I only see 2 small lines leaving the oil pump...the lines go to nipples on the intake runners (after the carb)

So if I run one line between those 2 nipples (as a way to block them off) and then run the 2 lines from the oil pump back to the reservoir (rather than having to remove the pump and block it off) then that should be all that is needed to run pre-mixed gas right?
 

·
Registered
Joined
·
16 Posts
Discussion Starter #5
I just got done trying it on mixed gas.
I took both oil lines off the intake runners and ran one line between them to block them off.
Put mixed gas in the tank and it did the same thing as before. It starts right up and has no trouble idling...but after you give it some gas the amount of smoke increases and then it will bog if you try to move and it will no longer idle.

Is it possible for plugs to foul so bad that you have to replace them? Ive taken them out, wiped them off and put a lighter to them. I don't see how they could be causing the problem but I don't know what else could cause it.
 

·
Registered
Joined
·
1,352 Posts
When a sled sits for a while, the oil that is in the crankcase and on the bottom of the pistons and on the crankshaft settles to the bottom of the crankcase. When you first start the thread, the airflow picks up that oil and adds it to the oil you are giving, and you get a lot more oil than necessary. The plugs foul. That's more common on a sled that has been fogged.

Also, the sled is jetted for cold conditions. Running those jets in warm conditions makes the air/fuel mix really rich, which also contributes to plugs fouling. I've had sleds that could not move onto a trailer in the hot summer sun that ran perfect when it got cold, simply because of the jetting.

Both those conditions usually clear up when it gets cold and you run the engine up to operating temperature while riding. You could try smaller jets as a test, but when it gets cold, you will need to jet appropriately for the temperature to prevent overheating of the pistons because of the lean condition.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #7
When a sled sits for a while, the oil that is in the crankcase and on the bottom of the pistons and on the crankshaft settles to the bottom of the crankcase. When you first start the thread, the airflow picks up that oil and adds it to the oil you are giving, and you get a lot more oil than necessary. The plugs foul. That's more common on a sled that has been fogged.

Also, the sled is jetted for cold conditions. Running those jets in warm conditions makes the air/fuel mix really rich, which also contributes to plugs fouling. I've had sleds that could not move onto a trailer in the hot summer sun that ran perfect when it got cold, simply because of the jetting.

Both those conditions usually clear up when it gets cold and you run the engine up to operating temperature while riding. You could try smaller jets as a test, but when it gets cold, you will need to jet appropriately for the temperature to prevent overheating of the pistons because of the lean condition.
I don't suppose there is any way to get settled oil from the crankcase other than to run the motor?
It would be great if that was the issue but I wonder since the old owner said it fouled on him in the winter.
Also, temps here are in the 50's...not that far from the 30 degrees it is likely jetted for.
 

·
Registered
Joined
·
1,352 Posts
I would consider other problems over too much oil. A sled will run pretty well if it's got good spark and good compression, even if it's got a lot more oil than necessary.

Try pulling the spark plug wires and unscrewing the ends (most sleds use a removable plug boot.) Look into the opening where the wire threads; you will see a small screw-like contact. Is it clean and shiny? If not, replace the boot. NGK sells a couple of different ones, the one-piece boots are a little nicer. Before screwing the plug wire back into the boot, snip about 1/4" of wire off. That will insure that you have a good wire contact. That will rule out the wire as a problem. Going with fresh plugs will rule out the plugs, too.

What's the compression?
 

·
Registered
Joined
·
16 Posts
Discussion Starter #9
I would consider other problems over too much oil. A sled will run pretty well if it's got good spark and good compression, even if it's got a lot more oil than necessary.

Try pulling the spark plug wires and unscrewing the ends (most sleds use a removable plug boot.) Look into the opening where the wire threads; you will see a small screw-like contact. Is it clean and shiny? If not, replace the boot. NGK sells a couple of different ones, the one-piece boots are a little nicer. Before screwing the plug wire back into the boot, snip about 1/4" of wire off. That will insure that you have a good wire contact. That will rule out the wire as a problem. Going with fresh plugs will rule out the plugs, too.

What's the compression?
compression is about 110psi on both cylinders.
 

·
Registered
Joined
·
1,352 Posts
Compression sounds fine, you could try idling it until the engine gets to operating temperature; that may help get rid of any excess oil that's in the crankcase. Then swap in new plugs.

Check for spark if it dies, you could have a coil or stator issue that only shows up when the engine is warm.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #11
I put in new plugs today. I was able to run it up and down the yard (20' back and forth on grass) and it would still idle after each pass. Still a lot of smoke, but the mixed gas in the tank is almost 50:1 which might be too much.

Here is what the new plug looked like after 5-6 minutes of running plus moving it 4-5 times.

The clutch sorta seemed like it engaged rather high...around 4K.
 

Attachments

·
Registered
Joined
·
1,352 Posts
That's pretty normal for engagement, especially with a small engine. 2-stroke engines don't produce much torque, so you really have to spin 'em to get any work out of them!

The plug looks pretty good to me. I think as long as the sled runs and idles when you stop, a lot of the smoke issue will go away once you can get it out on the snow and work it. It's really hard to judge anything by the plug in the temperatures you are running, the sled will run rich now, and that always makes the plug black. I don't see a ton of oil, which tells me you are making progress :)
 

·
Registered
Joined
·
16 Posts
Discussion Starter #13
I took off the carb
was surprised to find the inside of the bowl covered in rust.
cleaned up the carb, adjusted the float (seemed like it had to go up too high to close the needle) but none of that changed how the sled ran :(
 
1 - 13 of 13 Posts
Top